TOLL IMPACT STUDY. Final Report. August 2007

Transcription

1 TOLL IMPACT STUDY Final Report August 2007 Prepared for: Prepared by: Scottish Executive Enterprise Transport & Lifelong Learning Dept Transport Road Pricing Team Transport Analytical Services Victoria Quay Leith Edinburgh EH6 6QQ Steer Davies Gleave George Street Edinburgh EH2 2LR +44 (0)

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3 Contents Page EXECUTIVE SUMMARY i INTRODUCTION 1 1. CONTEXT 3 Background 3 Structure of this Report 4 2. ISSUES ARISING DURING CONSULTATION AND RESEARCH 7 Issues Identified by Respondents to Call for Evidence 7 Issues Identified by Primary Research 9 MODELLED IMPACTS MODELLING APPROACH 13 The Need for Modelling 13 Modelling of Strategic Movements 13 Modelling of Local Traffic 14 Modelling of the Local Economy 14 Use of the Modelling Outputs STRATEGIC TRAFFIC IMPACT 17 Background to TMfS 17 Drivers of Change 17 Description of Tests Undertaken 20 Results and Commentary 21 Conclusions LOCAL TRAFFIC IMPACT 25 Introduction 25 Models Provided 25 Creation of Micro-simulation Model Scenarios 28 Qualitative Assessment Tay Bridge Model 33 Quantitative Assessment Tay Bridge Model 37 Qualitative Assessment Forth Bridge Model 40 Summary of Findings MODELLED IMPACT ON THE LOCAL ECONOMY 43 Background to Dynamic Model 43 Scope of the Dynamic Model 43 Data Sources (Planning, Economic and Demographic) 47 Contents

4 Interface with TMfS 47 Description of Tests Undertaken 48 Conclusions 59 PRIMARY RESEARCH PRIMARY RESEARCH UNDERTAKEN 63 Overview 63 Public Sector 63 Private Sector 63 Focus Groups 64 Individuals PUBLIC SECTOR 65 Description of Methods Used 65 Findings Tay Road Bridge 65 Findings Forth Road Bridge 66 Commentary PRIVATE SECTOR 69 Description of Methods Used 69 Findings 69 Commentary INDIVIDUALS 75 Description of Methods Used 75 Focus Group Findings 76 Stage 2 Individual Survey Findings 79 Findings 83 APPRAISAL IMPACT APPRAISAL 87 Introduction to the Impact Appraisal 87 Summary of Impacts ASSESSMENT OF ENVIRONMENTAL IMPACTS 89 Impacts Assessed 89 Noise and Vibration 89 Air Quality 90 Global Emissions (CO 2 ) 90 Local Emissions (PM 10, NO X ) 91 Contents

5 Visual Amenity 91 Journey Ambience ASSESSMENT OF MONETISED IMPACTS 93 Impacts Assessed 93 Changes in Numbers of Accidents 94 Private Sector Impacts 95 Public Sector Impacts 102 Monetised Summary ECONOMIC IMPACTS 109 Transport Economic Efficiency Analysis 109 Local Economic Impacts 114 National Economic Impacts ASSESSMENT OF SOCIAL IMPACTS 121 Approach Taken 121 Summary of Social Impacts SUMMARY OF IMPACTS 127 Introduction 127 Modelling 127 Economic Activity Impacts (both bridges) 128 Modelling and Research 129 Issues and Constraints to Removing the Tolls 130 DISCLAIMER NOTICE 133 Contents

6 FIGURES Figure 3.1 Summary of Modelled Approach and Use of Modelled Outputs 15 Figure 4.1 Northbound Weekday Flow over Forth Road Bridge (FETA count data Jan-May 2006) 18 Figure 4.2 Southbound Weekday Flow over Tay Road Bridge (Slip Road count data Jan-July 2006) 19 Figure 4.3 Plot showing difference between Reference Case and Without Tolls Case 2010 (Annual Average Daily Traffic) 23 Figure 5.1 Tay Bridge Paramics Model 26 Figure 5.2 Forth Bridge Paramics Model 27 Figure 5.3 TMfS Data Request for Tay Bridge Study Area 29 Figure 5.4 TMfS Data Request for Forth Bridge Study Area 30 Figure 6.1 Dynamic Model Zones Aggregated to Reporting Units 45 Figure 6.2 Change in Travel to Work Movements To Edinburgh By Origin Area (Base Case) 55 Figure 6.3 Change in Travel to Work Movements With Fife as Destination By Origin Area (Base Case) 56 Figure 6.4 Change in Travel to Work Movements With Dundee as a Destination By Origin Area (Base Case) 57 Figure 6.5 Mode Split for Travel to Work movements (Fife to Edinburgh and the Lothians) (Base Case) 58 Figure 6.6 Mode Split for Travel to Work movements (Fife to Dundee and Angus) (Base CAse) 59 Figure 14.1 Transport Economic Efficiency Table for Simultaneous Removal of Tay and Forth bridge tolls (Base Case) in Figure 14.2 TEE Table for Simultaneous Removal of Tay and Forth bridge tolls (Reduced-Reassignment) in Figure 14.3 Public Accounts Table for Simultaneous Removal of Tay and Forth bridge tolls (Base Case) in Figure 14.4 Public Accounts Table for Simultaneous Removal of Tay and Forth bridge tolls (Reduced-Reassignment) in Contents

7 TABLES Table 4.1 Table 4.2 Table 4.3 Table 5.1 Table 5.2 Table 5.3 Table 5.4 Table 6.1 Table 6.2 Table Base Year Hourly Typical Weekday Traffic Flows from TMfS and 2006 Observed Counts (Total vehicles) TMfS modelled impact of removing Forth Road Bridge tolls TMfS modelled impact of removing Tay Road Bridge tolls Expected Tay Bridge Flows by Scenario (from TMfS) Expected Forth Bridge Flows by Scenario (from TMfS) AM Peak Average Journey Times in the Tay Bridge Model (in seconds) PM Peak Average Journey Times in the Tay Bridge Model (in seconds) Change in Key Indicators between No Tolls and Tolls Model Runs (base Case) Change in Key Indicators between No Tolls and Tolls Model Runs (Reduced-reassignment Assumptions) Changes in Travel to Work Trips by Aggregate Area Between No Tolls and Tolls Model Runs Table 13.1 Annual Accident Statistics (Base TMfS, 2015 forecast year) Table 13.2 Annual Accident Statistics (Reduced-Reassignment TMfS) Table 13.3 Full TMfS Base Highway User Impacts Table 13.4 Full TMfS Reduced-Reassignment Highway User Impacts Table 13.5 Full TMfS Public Transport Impacts Table 13.6 Full TMfS Base Private Sector Impacts Table 13.7 Full TMfS Reduced-Reassignment Private Sector Impacts Table 13.8 TMfS Tay Sub-Area Base Highway User Impacts Table 13.9 TMfS Tay Reduced-Reassignment Sub-Area Highway Impacts Table Tay Bridgehead Base Paramics User Benefits (AM Peak) Table Tay Bridgehead Reduced-Reassignment Paramics User Benefits (AM Peak) Table Tay Bridgehead Base Paramics User Benefits (PM Peak) Contents

8 Table Tay Bridgehead Reduced-Reassignment Paramics User Benefits (PM Peak) Table TMfS Forth Sub-Area Highway User Impacts Table Overall Base Model Private Sector Impacts Table Overall Reduced-Reassignment Model Private Sector Impacts Table Overall Public Sector Impacts Table Overall Public Sector Impacts Table Analysis of Monetised Costs and Benefits (Base Model) Table Analysis of Monetised Costs and Benefits (Reduced-Reassignment Model) Table 14.1 Modelled Impacts of Removing Tolls from Both Bridges: jobs filled (Base Case) Table 15.1 Tay and Forth infrequent users what would have to change for you to make more journeys? Table 15.2 Infrequent Bridge Users Additional Journey Purposes if their Current Priority Areas Were Removed APPENDICES (BOUND SEPARATELY) A B C D E F G EVIDENCE REPORT TMFS TECHNICAL PARAMICS TECHNICAL DYNAMIC MODEL TECHNICAL MARKET RESEARCH FINDINGS ENVIRONMENTAL APPRAISAL DETAIL ECONOMIC APPRAISAL DETAIL Contents

9 EXECUTIVE SUMMARY Context 1. This study provides a largely quantitative assessment of the effects of removing tolls on the Forth and Tay road bridges. It focuses on the impacts on Fife and the greater Dundee area, but some effects, such as those on employment, consider a wider area. It is intended that this study will provide the Scottish Executive with robust evidence of the impacts of tolls on the Forth and Tay road bridges. 2. The study examines the traffic, economic, social and environmental impacts and the financial and wider costs of retaining or abolishing the tolls on each bridge. The focus of the study is on the impacts of retaining or removing the tolls first in terms of changes in bridge traffic, and then on the consequences of these changes on the economy and local communities in Fife and Dundee and on the environment. 3. The impacts of removing the tolls have been assessed against objectives consistent with Scottish Transport Appraisal Guidance (STAG), which ensures that the economic, environmental and social impacts are addressed in a consistent and standardised manner. The critical and central issue is the traffic impact and whether the reduction in the financial cost of travelling over the bridge leads to changes such as alteration of route by car and other vehicles; traffic generation or suppression; or combinations of these effects. Understanding this is fundamental, as the economic, environmental and social consequences stem from this. Impacts/Findings 4. The main effects for each bridge are broadly similar but of a different magnitude. The impact of removing the tolls on the Tay Bridge would create a greater percentage change in travelling behaviour than on the Forth Bridge, including re-routing from the A90 via Perth. But far fewer people use the Tay Bridge so the economic and other impacts of this are not directly proportionate. The key findings for each bridge are presented separately below: 5. The Economic Activity and Location impact of removing the tolls on both bridges is a marginal improvement in the number of jobs filled in Scotland within the areas closest to the bridge the gain is negligible (< 0.01% of total current employment). There are slightly greater distribution gains, with Fife gaining 1,178 residents in employment but at the expense of other areas, especially Edinburgh and the Lothians. Dundee City also gains both in terms of jobs filled and employed residents. The study was unable to find any real evidence of significant social impact resulting from the existence or removal of the tolls. Findings: Tay Bridge 6. The surveys of bridge users and non-users indicate that the financial cost of the toll on the Tay Bridge makes very little difference to the extent to which people will travel to work or make business trips across the bridge, and no difference to freight traffic. However, the survey evidence indicates that removing the toll on the Tay Bridge Summary i

10 would prompt an increase in leisure trips made over the bridge, some of which would be made at or near peak times. 7. This is in line with the findings from the modelling work, which forecasts that, without a toll on the Tay Bridge, a proportion of drivers will switch route from the A90 to the A92 and the A91 through Fife. The Scottish Executive has invested in the A90 to make it a high capacity, improved safety dual carriageway route, whereas the A92 is partly, and the A91 is wholly, single carriageway; both provide less capacity than the A The toll does play a role in traffic management and helps to avoid potentially excessive use of single carriageway roads in Fife for strategic traffic heading towards the central belt. Therefore if an increase in traffic on the Tay Bridge and then on the A92/A91 is to be avoided, there is a need to retain the toll as a form of traffic management on the Tay Bridge. 9. Should a decision to remove the Tay Bridge tolls be made, the local transport modelling identified a number of locations on the Dundee road network that would require some degree of redesign/remodelling. These include the toll plaza and junctions on South Marketgait with East and West Marketgait and the merge from the northbound bridge ramp. 10. Dundee City Centre currently suffers from localised congestion, in part because of the design of the bridge ramps and the speed of toll collection. This was noted as a problem for drivers in the surveys. While the toll plaza could be relocated, this is an expensive solution. Delays accessing the bridge might be addressed by restructuring the ramps and speeding up the flow of traffic through the toll booths. The ramps could feasibly be redesigned as part of the Dundee Central Waterfront regeneration project. Measures which would speed up the flow of traffic through the toll booths may include the adoption of electronic tolling and/or a tag or voucher system. 11. The regeneration of central Dundee is a major project which could have significant local economic benefits. It is noted that the regeneration of the Dundee Central Waterfront has not yet been included in the Transport Model for Scotland and therefore was not included in the modelling undertaken. 12. While it is not within the remit of this study, our research shows that respondents believe that the 1 payment on the Forth is a convenient and efficient amount to pay, which some respondents said contributes to fewer delays in paying the toll. Use of an amount such as 1 potentially could lead to increases in the speed of toll collection on the Tay if this was adopted instead of the current 0.80 charge. 13. Assessed against the appraisal objectives consistent with STAG, the removal of tolls would lead to increased global and local traffic emissions and some level of increase in traffic noise; against the environment objective the proposal has adverse impacts. The monetised transport impact assessment undertaken demonstrates that the net private sector impact is positive; however the loss of public sector toll income is more than twice this impact in scale. Removing the tolls from the Tay Bridge would not represent value for money ; this remains the case over a tested range of traffic reassignment between the alternative strategic routes. ii Summary

11 14. For the reasons outlined above it is recommended that the tolls on the Tay Bridge are retained, but also recommended that measures to speed up toll collection are investigated. Findings: Forth Bridge 15. The surveys have identified that people using the Forth Bridge to travel to work would not travel any more or less if the toll were abolished. The surveys also indicate that between 25% and 30% of leisure users would use the bridge more frequently if tolls were removed. Some leisure trips (15%) are currently made during peak hours and it is likely that some increase would take place at peak hours, but most would take place outside the current peaks. 16. Survey respondents indicated that in response to worsening congestion most would alter the timing of their travel, but would not consider more drastic changes: few said they would change how they travel. Together all of these factors suggest increasing congestion and longer peaks on the bridge in the absence of tolls. 17. The Transport Model for Scotland indicates that there would be some increase in demand for the bridge during peak hours if the toll were abolished, mainly through rerouting by drivers who currently actively avoid paying the toll. 18. As with the Tay Bridge, research undertaken with the private sector showed that the tolls on the Forth Bridge make no difference to the propensity of freight vehicles or people on business trips to cross the bridge. 19. As the Forth Bridge is already operating at capacity during peak hours, the increase in demand which would be created by removing the tolls would extend the peak period and cause queues to lengthen. Traffic congestion is a concern for almost everyone surveyed and travelling behaviour is more sensitive to this than to the financial cost of bridge tolls at their current level. The response to congestion of people travelling to work is to adjust the time at which journeys are made, rather than to reduce the number of journeys made. 20. Should a decision to remove the Forth Bridge tolls be made, the layout of the area of the current toll plaza would need to be completely remodelled. This could include a review of the balance of priority given to the A90, the A904, the A8000 and the future M9 spur. 21. Despite an increase in congestion, the economic and land-use modelling work shows removal of the financial cost of the toll from the Forth Bridge does lead to a marginal but positive local economic impact for residents of Fife, as Fife residents gain employment outside Fife at the expense of residents of other areas, especially Edinburgh and the Lothians. Part of this is the (small) added stimulus to migration to Fife due to the lower financial costs of travel, although typically the major effects here are driven by property prices. It is harder to predict longer term effects on the Fife economy that may arise from higher levels of congestion. It is possible that the economic base could be weakened if people with very high values of time such as senior professionals and business owners, leave the area because they are more intolerant of congestion than other residents. Summary iii

12 22. To conclude, congestion would increase if the tolls were removed from the Forth Bridge because leisure trips, some of which are made during peak hours, would increase and the peak periods would be extended. The vast majority of survey respondents were considerably more concerned about congestion than about the financial cost of the bridge toll, but the main response to congestion would be to change travel times. This would tend to extend the length of periods of heavy congestion. 23. In terms of the impact appraisal undertaken the removal of tolls would lead to increased global and local traffic emissions and some level of increase in traffic noise; against the environment objective the proposal has adverse impacts. The monetised transport impact assessment undertaken demonstrates that the disbenefit of congestion considerably outweighs the benefit of removing the cost of the tolls; taken with the loss of public sector toll income the overall impact on the study area is negative. Removing the tolls from the Forth Bridge would not represent value for money. 24. For the reasons outlined above it is recommended that the toll on the Forth Bridge is retained. iv Summary

13 INTRODUCTION 1

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15 1. CONTEXT 1.1 This study has been prepared in response to a project brief from the Scottish Executive Enterprise, Transport and Lifelong Learning Department. It consists of a quantification of the impact of the toll on the economy of Fife, the Lothians and the greater Dundee areas. It is intended that this study will provide the Scottish Executive with robust evidence of the impacts of toll on the Forth and Tay road bridges. As indicated in the study brief, each bridge is considered separately. 1.2 The study examines the traffic, economic, social and environmental impacts and costs of retaining or abolishing the tolls on each bridge. The focus of the study is on the impacts of retaining or removing the tolls first in terms of changes in bridge traffic, and then on the consequences of these changes on the economy and local communities in Fife and Dundee and on the environment. 1.3 In accordance with the principles set out in Scottish Transport Appraisal Guidance (STAG), the study also examines the impacts at wider spatial levels, which include the national level and appropriate regional levels. 1.4 The impacts of removing the tolls have been assessed against objectives consistent with Scottish Transport Appraisal Guidance (STAG), which ensures that the economic, environmental and social impacts are addressed in a consistent and standardised manner. The critical and central issue is the traffic impact and whether the reduction in the financial cost of travelling over the bridge leads to mode switch from rail or bus; or traffic generation; or both? Understanding this is fundamental, as the economic, environmental and social consequences stem from this. Background 1.5 In 2003, the Scottish Executive s Partnership Agreement included a commitment to improve access for our rural communities by reviewing existing bridge tolls in Scotland and entering into negotiations with a view to ending the discredited toll regime for the Skye Bridge. Phase One of the Tolled Bridges Review included an examination of the impact of the existing tolling structures, and the way in which potential changes to tolls could help achieve the Scottish Executive s environmental and economic objectives of reducing pollution and congestion. 1.6 Phase Two included an examination of the broader issues relating to the management, operation and maintenance of the remaining tolled bridges, culminating on 1 March 2006 when the Minister for Transport, Tavish Scott, announced (amongst other things) that tolling would end at the Erskine Bridge from 31 March Scottish Ministers took the decision that tolling should continue at the remaining two bridges the Tay and the Forth. At the Tay Bridge, the primary reason for retaining the tolls was to meet the loan debt associated with the construction costs of the Bridge, which have not yet been fully recovered. This amounted to approximately 13 million. In addition, traffic modelling indicated that the removal of tolls would cause increased traffic and congestion in Dundee city centre, exacerbating the air quality problems in the Air Quality Management Area. 3

16 1.8 At the Forth Road Bridge, the primary reason for retaining the tolls is to manage traffic demand. The bridge runs to capacity at peak times, peaks are spreading, and there are severe congestion problems associated with the bridge. In both cases toll income funds the maintenance and upkeep of the bridges, and thus their availability to users. 1.9 Following the announcement on 1 March 2006 the Scottish Parliament sought to consider the impact of tolls further. On 30 March 2006, following a debate on bridge tolls, the Parliament agreed to recommend: an examination of the economic, social and environmental impact and cost of retaining or removing the tolls from the Tay and Forth bridges, on Fife and Dundee, the proposals for which will be reported on as soon as possible 1.10 In advance of this study, interested parties were invited to submit to the Scottish Executive any factual evidence in support of the retention or removal of tolls from the bridges. While this was an open invitation, letters were sent to around 180 individuals and organisations on 1 June Recipients included all MSPs, relevant local authorities, regional transport partnerships, bridge authorities, non government organisations, motoring organisations and public transport representatives. The closing date for these submissions was 17 August The purpose of this commission is to fulfil the requirements of the Parliament in respect to the commitments described above, and as articulated in the project brief. The objectives are to: Provide an assessment, in relation to the aim of the Study, of the submissions received by the Scottish Executive in response to the Minister for Transport s call for evidence on 17 May 2006 Provide an assessment, in relation to the aim of the Study, of the traffic, economic, environmental and social impacts of retaining and removing the bridge tolls from one or both bridges 1.12 The study addresses the immediate, short to medium term and, where possible, long term impacts of each of the tolling scenarios. Structure of this Report 1.13 This document is structured into four main parts, each setting out a different aspect of the study. The first part includes this introductory section and Section 2, which sets out the key issues identified by respondents to the Minister s call for evidence and those identified in this study. Modelled Impacts 1.14 The second part of this document describes the modelling approach taken to forecast the various impacts of removing the tolls on the Tay and Forth bridges. Section 3 introduces the overall modelling methodology, while Sections 4 and 5 set out further detail of the strategic and local forecasting techniques employed respectively. 4

17 1.15 Section 6 provides details of the Dynamic Modelling framework, developed by Steer Davies Gleave, and how it has been applied to this study. The Dynamic Model forecasts the impact of removing the tolls on the local economy including measures of access to employment/employees and to customers/suppliers. Primary Research 1.16 The third part of this document sets out details of the primary research undertaken during the course of this commission and provides a summary of the outcomes of that research. Section 7 introduces the research undertaken while Section 8 sets out details of the research with the public sector; Section 9 research with the private sector; and Section 10 research undertaken with individuals. Appraisal 1.17 The final part of the report brings the various findings together into the STAG based impact assessment framework and examines the overall cases for removing tolls on the two bridges; this assessment framework is introduced in Section 11. The environmental impacts of the proposal are considered in Section 12. The assessment of the monetised impacts/value for money undertaken is set out in Section 13. Section 14 draws together the economic impacts with Transport Economic Efficiency (TEE) analysis and various other elements of an Economic Activity and Location Impacts (EALI) analysis. Section 15 details the social impact analysis undertaken Finally Section 16 brings together the results of the modelling, research and appraisal and sets out the conclusions of the study. 5

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19 2. ISSUES ARISING DURING CONSULTATION AND RESEARCH 2.1 In advance of this commission, interested parties were invited to submit to the Scottish Executive any factual evidence in support of the retention or removal of tolls from the bridges. While this was an open invitation, letters were sent to around 180 individuals and organisations on 1 June Recipients included all MSPs, relevant local authorities, regional transport partnerships, bridge authorities, non government organisations, motoring organisations and public transport representatives. The closing date for these submissions was 17 August The main findings from the information received are summarised below and a report on the call for evidence responses can be found in Appendix A. 2.2 To complement the information received in response to the call for evidence, this commission has included a comprehensive programme of primary research. The purpose of the primary research was to establish the extent to which respondents are concerned about the tolls and what impact (if any) they consider the tolls have on their travelling behaviour. The research consisted of four methods as follows: Face-to-face Telephone Focus groups Individual surveys 2.3 Target groups for primary research included a representative cross-section of bridge users, individuals who do not use the bridges, and relevant public sector organisations. This included: Individuals The private sector (employers, transport operators & the business community) The public sector (local authorities, local enterprise companies, local economic forum, etc) 2.4 The key points of the results of the primary research are summarised later in this section, and presented in more detail in sections 8 (public sector), 9 (private sector), 10 (individuals) and 15 (social impacts). Issues Identified by Respondents to Call for Evidence 2.5 The majority of information submitted was from respondents who object to the continuation of tolls on one or both the Tay and Forth Bridges. This was particularly prevalent in material submitted by individuals, organisations representing the business community, and MSPs. Some of these issues can be applied equally to both bridges. Examples include: The issues of fairness and equality of people in the East of Scotland, particularly in Fife (which is affected by both bridges), paying bridge tolls whilst similar tolls have been discontinued on other structures such as the Skye and Erskine Bridges 7

20 The toll revenue being used to pay for maintenance rather than the original construction costs. (This is cited as an anomaly because the Scottish Executive pays for the maintenance of other trunk road bridges throughout Scotland) 2.6 Other information offered against the tolls relates specifically to one bridge only, in most cases the Tay Bridge. Examples include: The Paramics model of traffic flow in Dundee The social implication of patients and visitors travelling from Fife to receive health care at Ninewells Hospital 2.7 One issue which was repeated in the submissions in relation to the Tay Bridge was not specifically about the tolls themselves, but about the decision making process to determine whether they should remain or be abolished. The respondents which cited this issue raised doubts about the wisdom of virtually doubling the amount of debt (from 13 million to an estimated 26 million) to move the toll collection plaza when the 13 million of new investment could be used instead to cancel the existing debt and remove the tolls. 2.8 Of the two bridges, the factual submissions against tolls are stronger in relation to the Tay Bridge. There are two consistent pieces of information which suggest the tolls here cause road traffic congestion and consequently environmental implications in Dundee. This information included: Dundee s Paramics model of traffic flow Industrial action on 28 March 2006 by bridge staff during which vehicles crossed the bridge without paying the toll 2.9 Relative to that for the Tay Bridge there was a smaller body of submitted information pointing to the removal of tolls on the Forth Bridge, and some respondents withheld from stating a preference with regards to tolls on the Forth Bridge until more information is available regarding the potential requirement for a new crossing The submissions in favour of tolls can generally be applied equally to the tolls on both bridges. Such information was submitted by environmental organisations and a passenger transport operator. Most of the issues raised do not simply point to the need for the tolls to be retained in their current form. Rather, the respondents state the tolls should be retained but modified. Examples of the modifications proposed include: Varying or increasing the tolls to manage demand more effectively Making public transport vehicles (in this case buses) exempt from paying tolls 2.11 Some of the information submitted conflicts with that presented by other parties. For example, most of the responses in favour of retaining the tolls suggest that tolls are (or can be) an effective means of managing traffic demand on and around the bridges. This is directly at odds with some of the submissions in favour of abolishing the tolls such as the submission in favour of abolishing the Tay Bridge toll which states that traffic on the bridge has increased disproportionately compared to other routes into Dundee, despite the toll. 8

21 2.12 Little of the information submitted truly represents hard factual evidence. However, it is not possible to scientifically analyse, validate or discount any of the claims because more detail is required about various sensitivities in relation to the tolls at each bridge. Specifically it is needed to know: The extent to which the volume of traffic crossing each bridge is sensitive to congestion The extent to which traffic congestion is related to how the toll is collected The extent to which the volume of traffic crossing each bridge is sensitive to the financial cost of the toll 2.13 The primary research element of this study will provide a guide in relation to these sensitivity issues and to the social impact of the tolls. On this basis the modelling phase will provide more quantified evidence in relation to whether removing or retaining the tolls would prompt greater or less congestion. Further analysis will then indicate the likely environmental and economic impact of the tolls. Issues Identified by Primary Research 2.14 In the focus groups, across all user groups the financial cost of the tolls were considered to be insignificant and people stated their belief that removing the tolls would have no effect on the volumes of traffic on either bridge nor on the frequency of their own journeys across either bridge. In particular businesses and freight operators stated that paying the toll was considerably cheaper than the costs of diverting to alternative routes. There was a general belief among focus group members that toll collection and the design of the toll plazas are the causes of congestion at both bridges In the user and non-user surveys the majority of respondents consider that the removal of the toll charge would have little or no impact on traffic volumes, routes chosen or modes used. Tay bridge respondents who were not working or seeking work did however say they would travel more for a variety of purposes if tolls were removed. Responses suggested that some additional leisure trips may be generated by individuals in this group, whereas there would be a smaller impact on people who travel for work purposes although among these there was also some scope for more non-work travel. Noting the timing of some leisure trips, it appeared possible that some extra traffic would be generated at peak times, adding to existing peak hour congestion Similar findings emerged from the Forth Bridge surveys, with indications that removal of the tolls might increase the frequency of non-work travel and potentially the choice of mode for both work and non-work travel. Again the timing of some non-work travel indicated that there would be an increase in such travel at peak times if tolls were removed, which would add to the present levels of congestion on the bridge especially at peak times. 9

22 2.17 Congestion on and around both bridges was highlighted as a major concern by all user groups, and survey respondents were asked how they might respond to worsening congestion. Responses indicated that people would principally change the timing of journeys where this is possible, and some would consider using public transport. However, it was evident that people did not, in a survey situation, contemplate more radical changes such as moving house and/or place of employment in the face of worsening congestion Sections 7 to 10 of this report set out the primary research undertaken over the course of this study, with Section 7 forming an introduction to the research programme. Further details of research undertaken with the public sector can be found in Section 8, with the private sector in Section 9 and with individuals in Section

23 MODELLED IMPACTS 11

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25 3. MODELLING APPROACH The Need for Modelling 3.1 This study has addressed the issues associated with the impact of the bridges tolls in a number of ways. A key part of this approach is the use of interdependent detailed modelling to assess the impact of the removal of the tolls on three key areas, namely: Strategic movements in the surrounding area The traffic flow local to the bridgeheads The local economy 3.2 The inclusion of the latter two of these takes forward two of the key recommendations of the additional work in Phase Two of the Tolled Bridges Review concerning economic analysis and detailed analysis of the bridgeheads. 3.3 The different nature of these is such that different, well-established, modelling approaches have been taken in each of the three areas. This section explains in outline the need for these modelling approaches and how they relate to each other. The following sections then provide more detail of the approaches and the conclusions of the modelling. Modelling of Strategic Movements 3.4 A change to the tolls on each bridge will bring about a change to traffic at two distinct levels: At the strategic level the removal of the tolls will affect the route choice of those travelling through the area for which the bridge presents a viable alternative (and a number of related impacts such as mode choice), causing a change in demand undertaking strategic movements This change in strategic movements and the potential removal of the toll collection and associated network changes will have an impact on local traffic movement 3.5 There are widely-accepted modelling approaches which will quantify both of these impacts. For the strategic level forecasting this usually means the use of a four stage multi-modal model. The standard model for much of Scotland, maintained by Transport Scotland, is the Transport Model for Scotland (TMfS). For this study TMfS has been used to forecast the impact of the removal of tolls on strategic movements, in terms of the flow on major route sections in the study area at peak and off-peak times of day. As would be expected for a specific use of a comprehensive national model, the model outputs have subsequently been reviewed in some depth. An overview of this part of the study is included as Section In addition, TMfS provided key inputs to the other two strands of modelling: changes in strategic traffic flows to the local traffic modelling and changes in transport costs to the local economic modelling, as discussed below. 13

26 Modelling of Local Traffic 3.7 TMfS forecasts the impact of changes to the tolls on strategic movements such as inter-urban travel and commuting from without the immediate urban area. In doing so it makes a high level assessment of the impact of individual elements of the road network, such as key junctions and other infrastructure such as the bridges. However, it is not designed to model these in detail. As this study focuses on the two bridges it was necessary to quantify the impact on local traffic using a more detailed modelling approach as recommended in the Tolled Bridges Study: Phase 2 Additional Work report. 3.8 The local traffic modelling approach taken is the use of micro-simulation in the immediate area of each bridge. Micro-simulation models forecast the movement of individual vehicles travelling around detailed road networks using simple rules, in contrast to traditional model such as TMfS which provide an aggregate representation of traffic. This more detailed representation of actual driver behaviour gives the ability to model complex road junctions and congested networks, and at the same time provide a visual representation of the proposed effects on traffic operations. 3.9 The timescales of this study were such that new models could not be developed so existing models for both bridges (both using Paramics software) were sourced and reviewed for both base and future years. Future year forecasts of traffic local to each bridge were then generated using changes in flow data from the TMfS modelling both for future year reference cases, with the tolls still in place, and tests cases with the tolls removed. The resulting model outputs quantify how well the existing road network (or committed future year network in the case of the Forth Bridge) will cope with future year traffic flows with or without the changes to the tolls in terms of changes to overall delay and average queue lengths. An overview of this part of the study can be found in Section Preferably, the delay outputs from the micro-simulation modelling would be fed back into the TMfS model (and further iterations between the models carried out) to better reflect the actual impacts at each bridge. This was not practical within the time constraints of this study The model used for the Forth Road Bridge analysis was unable to provide robust outputs due to problems with the network outside the immediate vicinity of the bridge with the future traffic demand forecasted both with and without tolls. Due to the time constraints given for the reporting of this study, these issues were unable to be resolved. Modelling of the Local Economy 3.12 A change to the tolls on each bridge will bring about changes to traffic costs, to traffic levels and, subsequently, to traffic delay. These will impact on local economic activity as people and businesses adapt in response. This study has used a detailed modelling approach to quantify this impact on the local economy. It has also been able to estimate the impact of the local economic modelling on the forecasts of strategic movements. 14

27 3.13 The approach makes use of the Dynamic Model, which has been developed by Steer Davies Gleave over recent years using the Systems Dynamics modelling approach to examine and explain the relationship between transport and economic activity in towns, cities and across regions. The model uses a large number of dynamic relationships describing the attractiveness of different geographical areas to different businesses, employees and customers to create base and future year estimates of economic activity in a study area covering both bridges. It then imposes changes in transport costs provided by TMfS model runs and the local forecasts of the costs of delay from the micro-simulation work, which changes the attractiveness and hence estimates an impact on the local economy. An overview of this part of the study can be found in Section 6. Use of the Modelling Outputs 3.14 The outputs from the different aspects of this study s modelling work have been brought together in the environmental, traffic and economic impacts parts of the final appraisal, summarised in the latter sections of this report. Figure 3.1 summarises the flow of information between the models and between the models and the final appraisal. FIGURE 3.1 SUMMARY OF MODELLED APPROACH AND USE OF MODELLED OUTPUTS Base: ref. case assumptions Test: Remove toll Transport Model for Scotland Strategic traffic flows Strategic transport costs Off peak time benefits Accident benefits Environmental benefits Micro-simulation Peak time (dis) benefits Transport Impacts Detailed delay impact Dynamic Model Local economic impacts Economic Impacts Environmental Impacts 3.15 This figure shows actual data flows between the models that have been used and as model outputs used in the formal appraisal. It shows that, while TMfS provides the bulk of the model outputs into the appraisal, the detailed local impacts come from the other modelling: the local traffic impacts from the micro-simulation in the shape of the peak hour time (dis)benefits and the local economic impacts from the Dynamic Model. 15

28

29 4. STRATEGIC TRAFFIC IMPACT Background to TMfS 4.1 Demand forecasting for changes in strategic movements for future years and due to the removal of the bridges tolls has been undertaken using the Transport Model for Scotland (TMfS). TMfS is Transport Scotland s multi-modal demand and assignment model that enables themselves, the wider Scottish Executive and Local Authorities to assess major inter-urban road and public transport schemes and major transport policy options. It is a development of the Central Scotland Transport Model (CSTM3) series, which now covers 95% of Scotland s population and has recently been rebased to 2005 observed data. 4.2 TMfS combines a number of functions: it is a repository for the most up-to-date transport and land-use data; provides strategic level future year forecasts, particularly for inter-urban trunk roads; and forecasts the impact of the introduction of major road or public transport schemes. 4.3 Use of TMfS provides consistency both with previous phases of the Tolled Bridges Review and similar strategic level appraisals for Transport Scotland and Scottish Executive. In addition to providing the forecasts for the strategic level impacts of removing the tolls it provides inputs to the more detailed aspects of the modelling: the impact on local traffic and the local economy. Drivers of Change 4.4 The starting point for all of the forecasts is the base case whereby current demand data is assigned to the transport network and the resulting traffic flows are validated against observed counts, in this case recent counts representing the 2005 base year. Table 4.1 shows the base year flows taken from TMfS compared to the most up-todate average road counter data available, from the first part of The three periods modelled by TMfS are the AM and PM peak hours and an average Interpeak hour. It is worth noting that the peak hour modelled (08:00 09:00) does not necessarily coincide with the peak hour of traffic over the bridges this is particularly true of the AM Peak over the Forth Bridge, where the actual peak hour is 07:00-08:00 due in part to its location in relation to Edinburgh City Centre and other employment destinations. TABLE BASE YEAR HOURLY TYPICAL WEEKDAY TRAFFIC FLOWS FROM TMFS AND 2006 OBSERVED COUNTS (TOTAL VEHICLES) TMfS Observed Counts Forth AM IP PM AM IP PM Northbound 2,800 2,200 3,600 2,700 1,900 3,300 Southbound 3,300 2,500 2,900 3,300 2,000 2,800 Tay Northbound 1, ,000 1, Southbound , ,400 17

30 4.5 Table 4.1 shows the expected peak flows northbound in the evening peak over the Forth Bridge and southbound in the morning peak. The peak flows in TMfS agree well with the counts, although TMfS shows an evening peak flow slightly higher than the morning; most likely in part because the morning peak modelled does not quite coincide with the actual morning peak over the bridge. TMfS also appears to give higher forecasts than the counts for the interpeak period, although this relatively uncongested period is less important to the final conclusions. This is partly due to the fact that, during this period, the contractor building the new toll plaza was allowed to reduce the flow in the PM Peak and Off Peak periods. 4.6 Finally, it is noticeable that there is a difference between the AAWT 1 (Average Annual Weekday Traffic) figures of 34,000 northbound and 35,500 southbound; suggesting that the presence of the tolls (northbound) causes some traffic to choose a route which avoids the bridge. 4.7 For the Tay the commuter peak into and out of Dundee is more pronounced and the morning peak flow is higher than the evening peak which is typical of commuting peaks. Again, in this case, the AAWT figures of 13,000 northbound and 12,400 southbound suggest that the presence of the tolls causes some traffic to choose a route which avoids the bridge. The quoted current Toll Booths capacity of 1,500 vehicles 2 is well below the notional capacity of the two lane carriageway of the bridge. 4.8 Figure 4.1 shows a weekday profile northbound over the Forth Road Bridge, showing maximum and average counts at the toll booths. Figure 4.2 shows the equivalent profile of demand in the tolled direction (southbound) for the Tay Bridge. FIGURE 4.1 NORTHBOUND WEEKDAY FLOW OVER FORTH ROAD BRIDGE (FETA COUNT DATA JAN-MAY 2006) Flow 2000 Max Average :00-01:00 01:00-02:00 02:00-03:00 03:00-04:00 04:00-05:00 05:00-06:00 06:00-07:00 07:00-08:00 08:00-09:00 09:00-10:00 10:00-11:00 11:00-12:00 12:00-13:00 13:00-14:00 14:00-15:00 15:00-16:00 16:00-17:00 17:00-18:00 18:00-19:00 19:00-20:00 20:00-21:00 21:00-22:00 22:00-23:00 23:00-24:00 Time 1 These are not strictly AAWT figures, but have been derived from the available data which was used to create the tables and figures, and are therefore consistent with these. This does not introduce a bias which would affect the north/southbound difference, but may mean a small difference in a precise AAWT value presented elsewhere. 2 Tolling Options Report, Hyder Consulting for Tay Road Bridge Joint Board 18

31 FIGURE 4.2 SOUTHBOUND WEEKDAY FLOW OVER TAY ROAD BRIDGE (SLIP ROAD COUNT DATA JAN-JULY 2006) Flow Max Average :00-01:00 01:00-02:00 02:00-03:00 03:00-04:00 04:00-05:00 05:00-06:00 06:00-07:00 07:00-08:00 08:00-09:00 09:00-10:00 10:00-11:00 11:00-12:00 12:00-13:00 13:00-14:00 14:00-15:00 15:00-16:00 16:00-17:00 17:00-18:00 18:00-19:00 19:00-20:00 20:00-21:00 21:00-22:00 22:00-23:00 23:00-24:00 Time 4.9 The future year forecasting element in TMfS is driven by the integral land-use model, which forecasts changes in key factors which drive the demand for transport such as employment, housing and car ownership. This future year demand is then assigned to an assumed future year transport network to give future year traffic flow forecasts Changes to the future year network cause changes to future year movements, both for the reference case and in the case where a particular scheme has been introduced. Comparison of these two cases gives an estimate of the impact of the scheme. This can be best illustrated in terms of the particular scheme currently being appraised removal of the tolls from a bridge The immediate impact of the toll removal will be a reduction in the cost of journeys over the bridge. There may also be a perception of improvement in the journey time in the direction that the toll must be paid because of the removal of the toll collection, although this is marginal in the case of the Forth Road Bridge where, in situations such as the PM peak, the capacity of the toll booths can match or better that of the bridge TMfS has a number of mechanisms which mean that this reduction in overall generalised cost make trips using the bridge more attractive. However this, in turn, means that journey times will be increased because of the additional congestion caused by the bridge s improved attractiveness. This reduces the demand, improving congestion and making the bridge more attractive again. This iterative process should eventually come to equilibrium. 3 There are 7 toll booths each of which can handle 520 vehicles per hour, making 3,640 vehicles per hour in total, just over the accepted capacity of a dual carriageway 19

32 4.13 Returning to the first iteration of the model described above, the mechanisms that translate the reduction in cost into an increase in demand can be split into assignment and demand mechanisms. The assignment model impacts include: Route choice, where a route involving the bridge becomes more attractive relative to another route which does not. Given the instantaneous nature of the toll and likely knowledge of alternatives, this impact is likely to take place over a relatively short time frame Mode choice, where the reduction in cost for travel by car will attract people away from public transport. This response would take longer to have an impact 4.14 The demand model impacts are not likely to take place overnight and therefore take place over a longer time period; these include: Destination choice, where a trip is more likely to be made to a destination via the bridge, rather than an alternative destination if it costs less Trip frequency, where a trip can be made more often if it costs less Peak spreading, where a trip is more likely to be made at peak times if it costs less relative to the cost at shoulder peak times, the periods immediately either side of the peaks 4.15 In addition there are even longer term land-use impacts which translate the improvement in accessibility for certain areas brought about by the reduction in cost into attractiveness in terms of employment and housing Given that some of these responses can take months, or even years, to have an impact, it is not easy to validate these modelled responses other than once the scheme being assessed has been introduced. For example, it is not possible to deduce the likely impact on the Tay Road Bridge from the reaction of drivers on the day in 2006 when the toll booth operators went on strike. Description of Tests Undertaken 4.17 For the purpose of this study a number of model runs were undertaken for two future years 2010 and For each year a reference case run was undertaken which reflects a realistic, if fairly optimistic, view of the schemes which are due to be in place for each year. Details can be found in Appendix C, but it is worth mentioning that the work currently being undertaken on the M9/A90 link road to the south of the Forth Bridge is assumed to be completed before 2010, and that the Dundee Waterfront has not been included in the reference case (because it is not included in TMfS) The main model runs to be undertaken involved the removal of the tolls from both the Tay and Forth Bridges. The run combined the two in one run in order to speed up the production of inputs to the other models. The work undertaken on behalf of the Scottish Executive in Phase 1 of the Tolled Bridges Review indicated little interaction between the two bridges, particularly in the tolled directions. This was confirmed to still be applicable with additional testing. 20

33 4.19 Additional sensitivity testing was undertaken to confirm TMfS reaction to the change in tolls by reviewing the impacts of increasing the tolls as well as removing them The resulting changes in strategic movements are summarised below, but it is worth noting that TMfS outputs also provided key inputs to the modelling of the impact on local traffic and the local economy For the local traffic modelling, TMfS provided an estimate of strategic movements at key points in the local network against which loadings in the local model could be checked given the difference in focus between the two models this represented little more than a check. More importantly TMfS provided an estimate of the changes in strategic movements at these key points. This is important because the local modelling only considers movements within the modelled area and not strategic level movements The Dynamic Model, which has been used to model the local economic impact (see Section 6) uses changes in transport costs to predict changes in the local economy. For this modelling, TMfS provided base generalised costs and changes in cost due to the removal of the tolls. Results and Commentary 4.23 Table 4.2 shows the results of the core tests that were undertaken using TMfS, the reference case and the removal of tolls for the Forth Road Bridge for the two test years of 2010 and The table shows the predicted total flow for each hour and the proportional impact of the removal of the tolls. All flows are rounded to the nearest 10 vehicles. More detailed results are available in Appendix B. TABLE 4.2 TMFS MODELLED IMPACT OF REMOVING FORTH ROAD BRIDGE TOLLS Reference case flow (vehicles) Difference in flow due to toll removal (veh) Percentage difference in flow AM IP PM AM IP PM AM IP PM 2005 N 2,790 2,240 3,550 S 3,330 2,500 2, N 2,990 2,440 3, % 21% 16% S 3,180 2,590 3, % 12% 10% 2015 N 3,010 2,670 3, % 13% 14% S 3,280 2,770 3, % 7% 7% 21

34 4.24 The reference case results suggest that in the peak direction the traffic has reached saturation point in both peaks, this is a combination of the capacity of the toll plaza and bridge configuration and the negative impact of congestion on peoples travel patterns. There is some room for growth in the interpeak period. The model assumes that there is still some room for a small amount of growth in the contra peak direction The modelled impact of the toll s removal on flows over the Forth Bridge is higher northbound than southbound and in 2010 than Neither of these relativities are surprising given that the toll is collected northbound and there is less capacity to accommodate the increase in 2015 than The magnitude of the impact, around 10%, is perhaps higher than might be expected given how close the bridge is already running to capacity These observations have been discussed with Transport Scotland and it should be noted that: the modelled peak hours in TMfS are based on those for the whole of Scotland which do not always coincide with those on the bridge, giving some room for growth; and the capacity constraining mechanisms in TMfS are less sensitive under high demand than reality. The constraints of the local road network on the forecast demand from TMfS will be provided by the local area micro-simulation models, as described in Section Table 4.3 shows the results for the Tay Bridge, with flows shown to the nearest 10 vehicles for clarity. The table shows that, in the reference case, there is no sign of reaching saturation point for the bridge at any time of day (but has exceeded the capacity of network and toll booths). The absolute size of the impacts are very similar for each year, and similar in magnitude to the size of the impacts on the Forth Bridge. The large difference between the impacts in each direction goes much of the way to redressing the balance between the two directions, due to the presence of the toll, as discussed above in describing Table 4.1. TABLE 4.3 TMFS MODELLED IMPACT OF REMOVING TAY ROAD BRIDGE TOLLS Reference case flow (vehicles) Difference in flow due to toll removal (veh) Percentage difference in flow AM IP PM AM IP PM AM IP PM 2005 N 1, ,010 S , N 1, , % 23% 28% S , % 45% 40% 2015 N 2, , % 21% 24% S 1, , % 40% 39% 22

35 4.28 The most striking results are the high modelled impacts southbound, an increase of demand of around 40%. This will have a significant impact on the local traffic, as detailed in Section 5. Again, this observation has been discussed with Transport Scotland and it seems that the main cause of the high impacts southbound is a high sensitivity to the cost change in terms of route choice and, to a lesser extent, trip generation, destination choice and peak spreading. The high impacts can also be partly attributed to the lack of detailed modelling of congestion and the capacity of the local road network to the north of the bridge, although this is less of an issue in this case this is, of course, addressed in the local traffic modelling The route choice issue is illustrated by Figure 4.3 which shows the difference between strategic movements in the reference case and the without both tolls case - the red illustrating an increase and the blue a decrease. The figure illustrates the large number of trips for which the cost difference is marginal between the M90/A90 route via Perth between, say Dundee and Dunfermline, and the alternative routes through Fife. For these trips the small change in cost due to removal of the tolls is enough to cause the route assigned by the model to switch. FIGURE 4.3 PLOT SHOWING DIFFERENCE BETWEEN REFERENCE CASE AND WITHOUT TOLLS CASE 2010 (ANNUAL AVERAGE DAILY TRAFFIC) 4.30 Whilst the base model closely matches observed journey times by both routes, there are other aspects of the journey, such as the higher reliability and safety on the A90/ M90 between Dundee and Fife which it will not capture. Sensitivity tests have been undertaken making the A90/M90 route more attractive in the reference and test cases, which suggest that a reduction of up to 5% on the 40% southbound impact may be appropriate this has been reported in some detail as the reduced-reassignment test Other sensitivity tests have been undertaken to reflect different assumptions about the commuting market and its reaction to congestion. Overall the results of sensitivity tests proposed by Transport Scotland suggest that the 40% - 45% impacts reported southbound for 2010 could be reduced to 25% - 35% using a more conservative approach this, of course, is still a significant impact. 23

36 Conclusions 4.32 The TMfS strategic model has been used mainly as an input to the other two strands of modelling: predicting changes in strategic movements for the detailed local traffic modelling and changes in transport costs for the local economic impact modelling. However, TMfS has also been used to quantify the likely change in strategic movements over time and sizeable changes in strategic movements associated with the removal of the tolls Whilst growth in peak traffic over the Forth Bridge is constrained by the capacity of the bridge, it is forecast to increase by around 15% in the interpeak period between 2005 and TMfS forecasts an increase of around 10% in movements due to the removal of the tolls, slightly higher in the northbound, tolled direction. This is higher than expected and is considered together with the results of the local traffic modelling in the report summary in Section Over the Tay Bridge TMfS forecasts an increase in flows of between 15% and 20% between 2005 and Removal of the tolls is forecast to result in an increase in flows over the Bridge of around 20% northbound and 40% southbound. The latter has been agreed to be at the high end of the expected range. A more conservative sensitivity test suggests a figure of around 30% may be more appropriate although this of course is still a substantial proportional increase. Again, this is considered together with the results of the local traffic modelling in Section

37 5. LOCAL TRAFFIC IMPACT Introduction 5.1 The micro-simulation modelling workstream concentrated on establishing the impact of the removal of tolls on network operation to a more local level. 5.2 In summary this element of work was carried out in four main stages: Obtain and review existing Forth and Tay Bridge models from third party sources Obtain demand data for different scenarios from the TMfS term consultant, and apply this demand data to represent the scenarios within the micro-simulation models Run models and obtain indications of network conditions under each scenario (qualitative assessment) Produce output to compare network operation under each scenario (quantitative assessment) 5.3 The following text provides a commentary on these four main stages, and any intermediate sub-stages. 5.4 The principal aim of the micro-simulation modelling element of the study is to provide guidance as to the impact on the local road network of changing the current toll charging strategy on both bridges. Models Provided 5.5 Micro-simulation models were obtained for both the Tay Bridge and Forth Bridge areas from previous studies as indicated below. Tay Bridge Model 5.6 A Paramics micro-simulation model was provided by Dundee City Council for both the weekday AM and PM peak periods, covering the area shown in Figure 5.1. The model was validated and calibrated at the base year of An initial review of the model showed that it was largely fit for purpose. Forth Bridge Model 5.7 Paramics micro-simulation models were provided by MVA for both the weekday AM and PM peak periods, covering the area shown in Figure This model was adopted by SESTRAN for the SESTRAN Integrated Transport Corridors Study (SITCoS). As such, this model concentrated on providing an optimum level of accuracy for traffic flow and conditions on and in the immediate vicinity of the A90/M90 corridor. Outlying areas of the model were modelled in less detail, one result of this was network instability under the future traffic demand forecasted both with and without the tolls. 25

38 FIGURE 5.1 TAY BRIDGE PARAMICS MODEL Tay Bridge N 26

39 FIGURE 5.2 FORTH BRIDGE PARAMICS MODEL Forth Bridge N 27

40 5.9 The base model was provided for the base year of In addition, a future network model was provided by MVA, including the committed A8000 scheme to the south of the bridge. This model was used in all 2010 and 2015 future year scenarios, rather than the existing network model It was eventually concluded that this model was unable to provide robust quantified outputs because of these problems. Due to the time constraints given for the reporting of this study, these issues were unable to be resolved. However it was possible to undertake a qualitative assessment of the impact of removing tolls from the Forth Bridge, which is presented later in this section. Creation of Micro-simulation Model Scenarios Interface with TMfS 5.11 The demand forecasts for seven scenarios were derived from TMfS: An existing toll (baseline) scenario at 2005 Future year 2010, existing toll Future year 2010, toll removed Future year 2010, toll removed, reduced-reassignment assumption Future year 2015, existing toll Future year 2015, toll removed Future year 2015, toll removed, reduced-reassignment assumption 5.12 A key element of the process was to rationalise the difference in zone structure between TMfS and two Paramics models. In order to control the transfer of demand data between the two different model types, two sets of data was requested from TMfS in each scenario: All zone to zone movements (internal and external) within the cordoned microsimulation network areas External zone origin and destination totals plus some additional internal link counts on critical links 5.13 Figure 5.3 and Figure 5.4 show the data requested for the two study areas. Creation of 2005 Existing Toll Scenarios 5.14 The zoning systems used in TMfS are at a more aggregate level than those in the Paramics models, in particular to the north of the Tay Bridge. As such it was considered more appropriate to retain the existing disaggregate demand data To obtain base 2005 models, National Trip End Model (TEMPRO) data was used. This database contains local information on trip movements on a district level, including forecasts of future trip growth based on committed development schemes. In this way, the 2002 Tay Bridge model and the 2004 Forth Bridge model were updated to the base year of The factors applied were as follows: Tay Bridge 2002 to 2005 AM growth = Tay Bridge 2002 to 2005 PM growth = Forth Bridge 2004 to 2005 AM growth = Forth Bridge 2004 to 2005 PM growth =

41 FIGURE 5.3 TMFS DATA REQUEST FOR TAY BRIDGE STUDY AREA 29

42 FIGURE 5.4 TMFS DATA REQUEST FOR FORTH BRIDGE STUDY AREA 30

43 5.16 Comparisons between the strategic demands in TMfS and the Paramics models were made to inform where differences should be taken into consideration when analysis of the results is undertaken. Further details of the comparison undertaken can be found in Appendix C The Tay Bridge model shows similar demands on the Tay Bridge in both models in both periods. In general other areas of the model show TMfS demands to be lower than local demands. This is an artifact of the much more aggregate zoning system in TMfS in central Dundee where intrazonal trips are not modelled. This comparison supports the use of TEMPRO growth for the upgrade of the 2002 Tay Bridge model to Similarly for the Forth Bridge model, traffic flows on the bridge are similar in both models, but significant differences are encountered elsewhere. Again this is due to the relative coarseness of the TMfS model and the low number of validation sites within the Forth Bridge network area, compared to the local Paramics model Consequently, as for the Tay Bridge model, the process of applying local growth to create the 2005 base model was considered to result in a more robust representation of the 2005 conditions than the direct application of TMfS demand data. Creation of Future Year Scenarios 5.20 As indicated earlier in this section, traffic data from TMfS was obtained for the four future scenarios. This data was directly compared against the TMfS 2005 base scenario, and the differences in traffic flow in each scenario applied Due to the differences in zone structure between the two model packages, a simplified approach was taken in applying TMfS demand data to the two Paramics models, for each scenario. This concentrated on categorising all Origin to Destination (or zone to zone) trips within the TMfS and Paramics models into four types, and applying a different method of matrix adjustment, depending whether the trip origin or destination was to an Internal zone (within the models) or an External zone (outside the models): External to Internal Calculate absolute difference between TMfS base and scenario origin (entry) flow for each external, and apply this difference to all destination internal zones as per the base 2005 Paramics model distribution Internal to External Calculate absolute difference between TMfS base and scenario destination (exit) flow for each external, and apply this difference to all origin internal zones as per the base 2005 Paramics model distribution External to External Calculate absolute difference between TMfS base and scenario individual origin to destination flow, and apply this difference to each individual origin to destination movement Internal to Internal No change applied, that is, Paramics base 2005 movements retained in all future year models. This was due in part to the complexity in aggregating zones due to differences in zone structure between the two models. In addition, there are no internal to internal trips using the bridge in either model, as in both models there are no internal zones south of the river. Therefore it was considered that there would not be a significant increase in accuracy by assessing any increase in internal trips in detail 31

44 5.22 It is important to note that all scenarios in 2010 and 2015 for the Forth Bridge model included the completion and opening of the A8000 link road. Further detail of the results of this process can be found in Appendix C These procedures resulted in the creation of all required matrices for the Paramics models for each scenario Tables 5.1 and 5.2 show the demand flows expected on the Tay and Forth Road Bridges respectively for each scenario. All flows are shown in passenger car units (PCUs) to take account of the impact of different vehicle classes using the bridge. TABLE 5.1 EXPECTED TAY BRIDGE FLOWS BY SCENARIO (FROM TMFS) Total Bridge Flows (PCUs) Year: Toll scenario: Toll No Toll Toll No Toll Traffic re-assignment: Base Normal Low Normal Normal Low Normal AM Tay Bridge (northbound) Tay Bridge (southbound) PM Tay Bridge (northbound) Tay Bridge (southbound) The comparison of TMfS flows by scenario for the Tay shows that there is a relatively consistent trend of growth in traffic using the bridge from the base year to the 2010 and 2015 tolled scenarios. The level of background growth appears higher between 2010 and 2015 than between 2005 and In the scenarios where the tolls have been removed, the bridge flows are consequently much higher. However, the difference in demand between the two reassignment scenarios is modest. TABLE 5.2 EXPECTED FORTH BRIDGE FLOWS BY SCENARIO (FROM TMFS) Total Bridge Flows (PCUs) 2005 BASE 2010 TOLL 2010 NO TOLL 2015 TOLL 2015 NO TOLL AM Forth Bridge (northbound) Forth Bridge (southbound) PM Forth Bridge (northbound) Forth Bridge (southbound) In the case of the Forth Bridge, the comparison of TMfS flows by scenario shows that, for the AM Peak, there is a small increase in northbound and a decrease in southbound bridge traffic from 2005 to 2010 in the tolled scenarios. As may be expected, in the PM Peak these trends are reversed with an increase in southbound traffic and a decrease in northbound traffic. The 2015 tolled scenario flows are higher than both the 2005 and 2010 tolled scenario in both directions and in both peaks The bridge flows in the no toll scenarios are significantly higher than in the tolled scenarios. In general there is lower growth between 2010 and 2015 in the no toll scenario than in the tolled scenario, including a slight decline in the PM peak Northbound. This suppression of growth is likely to be an impact of the higher level of congestion on the network in the no toll case. 32

45 Qualitative Assessment Tay Bridge Model 5.28 The following paragraphs describe the results of running the Tay Bridge models, in terms of providing a commentary of where operational problems were viewed It should be noted that due to the aggregate nature of the TMfS data applied to the Paramics model, impact on all local roads within the Paramics model will not be entirely accurate. However, as the base TMfS model has been validated against measured Tay Bridge flows, any impact on the operation of the network immediately adjacent to the bridge will be sufficiently robust. AM Peak 2005 Base Prior to 08:30, no problems are observed Between 08:30 and 09:05 there are intermittent periods of northbound queues on the bridge, predominantly due to blocking back from the signalised Riverside roundabout. On occasions these westbound queues extend back to the City Quay roundabout on South Marketgait, and back onto Tay Bridge to a point around 50m south of the toll plaza No problems from 09:15 No significant problems elsewhere in the model 2010 Existing Toll Prior to 08:30, no problems are observed Between 08:30 and 09:05 there are intermittent periods of northbound queues on the bridge, predominantly due to blocking back from the signalised Riverside roundabout. On occasions these westbound queues extend back to the City Quay roundabout on South Marketgait, and back onto Tay Bridge to a point around 50m south of the toll plaza No problems from 09:15 No significant problems elsewhere in the model 5.30 These results are as would be expected as TMfS forecast that the increase in demand flow levels between the 2005 base case and 2010 existing toll option was negligible No Toll Prior to 08:15, no problems are observed Between 08:30 and 09:30 northbound queues on the bridge extend back beyond the edge of the model (around 200m south of the Toll plaza). This is due to insufficient capacity on the westbound approach to the Riverside roundabout, and the bridge exit onto the eastbound carriageway of South Marketgait. Westbound queues also extend back along South Marketgait to the East Marketgait junction, with heavy queues also experienced on the Blackscroft and King Street approaches to East Marketgait 33

46 2010 No Toll, Reduced-Reassignment The operation of the network is similar to the normal 2010 no toll scenario 5.31 The results show that the increase in northbound movements across the bridge result in a significant increase in congestion on both directions of South Marketgait, but particularly the westbound approach to the Riverside roundabout. The relatively small difference in the northbound traffic demand for the bridge in the reduced-reassignment scenario has no significant impact on network operation in comparison with the normal-reassignment scenario Existing Toll Prior to 08:30, no problems are observed Between 08:30 and 09:30 there are intermittent periods of northbound queues on the bridge, predominantly due to blocking back from the signalised Riverside roundabout. On occasions these westbound queues extend back to the City Quay roundabout on South Marketgait, and back onto Tay Bridge to a point around 50m south of the toll plaza No significant problems elsewhere in the model 5.32 In summary, conditions are marginally more congested than the 2010 existing tolls scenario, although blocking back problems are generally still experienced intermittently rather than consistently No Toll Prior to 08:15, no problems are observed Between 08:30 and 09:30 northbound queues on the bridge extend back beyond the edge of the model (around 200m south of the Toll plaza). This is due to insufficient capacity on the westbound approach to the Riverside roundabout, and the bridge exit onto the eastbound carriageway of South Marketgait. Westbound queues also extend back along South Marketgait to the East Marketgait junction, with heavy queues also experienced on the Blackscroft and King Street approaches to East Marketgait 2015 No Toll, Reduced-Reassignment The operation of the network is similar to the normal 2015 no toll scenario 5.33 The results show that operation similar to the 2010 No Toll scenario. Although there are additional northbound trips on the bridge, because of downstream congestion these additional trips are unable to enter the modelled network, and therefore general network operation is no worse. The relatively small difference in the northbound traffic demand for the bridge in the reduced-reassignment scenario does not change the network operation significantly from the normal-reassignment scenario. 34

47 Summary 5.34 The application of growth, with the retention of the existing toll strategy, shows that there is not a significant deterioration in network performance from 2005 to However, the model predicts that the removal of the toll in future year scenarios 2010 and 2015 does result in significant congestion on South Marketgait, leading to queues extending back along the northbound carriageway of the bridge within the full AM peak period. This is as a direct result of the increase in bridge demand due to the removal of the toll From the assessments, the Riverside roundabout appears to be the principal constraint for westbound traffic exiting the bridge. From sample on-site observations, the operation of this roundabout is one of the critical junctions within Dundee. It may be possible to modify signal timings or make minor physical changes to increase capacity for the westbound approach, although such changes may have detriment to the operation of other approaches In terms of southbound movements across the bridge, increased demand was not as great as in the northbound direction (due to the tidal nature of trips towards Dundee in the AM peak), and therefore the removal of the toll plaza did not have any impact on the network in terms of additional trips moving towards the bridge. PM Peak 2005 Base Prior to 17:00, no problems are observed Between 17:15 and 17:45 there are intermittent periods of southbound queues towards the toll plaza from both directions. However, these queues do not generally affect the operation of through traffic on South Marketgait No problems from 17:45 No significant problems elsewhere in the model 2010 Existing Toll Prior to 17:00, no problems are observed Between 17:00 and 17:45 there are intermittent periods of southbound queues towards the toll plaza from both directions Queues also observed on the East Marketgait approach to the South Marketgait junction, blocking back through the Blackscroft junction No problems from 18: These results can be expected as the TMfS model predicted an increase in traffic using the bridge between 2005 and 2010 in the existing toll option, with a marginal increase in observed queues within the network. 35

48 2010 No Toll Prior to 17:00, no problems are observed Between 17:15 and 18:00 northbound queues on the bridge extend back beyond the edge of the model (around 200m south of the Toll plaza). This is due to insufficient capacity on the westbound approach to the Riverside roundabout, and the bridge exit onto the eastbound carriageway of South Marketgait No queues are experienced on the southbound approaches to the bridge From 17:15 to 17:30, the queues are observed on the southbound West Marketgait approach to the Westport roundabout, but these do not block back to the Dudhope roundabout 2010 No Toll, Reduced-Reassignment The operation of the network is broadly similar to the normal 2010 no toll scenario 5.38 The results show that the increase in northbound movements across the bridge result in a significant increase in congestion on both directions of South Marketgait, but particularly the westbound approach to the Riverside roundabout Although there is an increase on the bridge southbound, due to the removal of the toll plaza, access to the bridge is easier and thus no problems for southbound traffic are experienced. However, the increase in queues on West Marketgait show that increase in demand for the southbound move over the bridge is beginning to impact on network operation by The relatively small difference in the northbound traffic demand for the bridge in the reduced-reassignment scenario does not change the network operation significantly from the normal-reassignment scenario Existing Toll Prior to 16:45, no problems are observed At 17:00 queues are observed on both southbound approaches to the bridge, but not impacting on the operation of through South Marketgait movements By 17:15 problems in the operation of the Dudhope roundabout result in westbound queues blocking back around North Marketgait through Ladywell roundabout and into East Marketgait By 17:30 the above problems have resulted in the gridlock of the north-east quadrant of the model. After 17:30, the gridlock spreads to the rest of the model 5.40 In summary, background traffic growth to 2015 has resulted in operational problems within the network. However, it is considered that these problems are not related to the operation of the bridge No Toll Prior to 16:45, no problems are observed From 17:00, the operation of the network is similar to that experienced in the 2015 Existing Toll scenario, with gridlock by 17:30 36

49 2015 No Toll, Reduced-Reassignment The operation of the network is broadly similar to the normal 2015 no toll scenario 5.41 Again, background traffic growth to 2015 has resulted in operational problems within the network. However, it is considered that these problems are not related to the operation of the bridge. The relatively small difference in the northbound traffic demand for the bridge in the reduced-reassignment scenario does not change the network operation significantly from the reduced-reassignment scenario. Summary 5.42 Prior to 2015, the removal of the toll plaza results in the removal of any queues on the southbound approach directly onto the bridge. However, there are early indications that the increase in demand for southbound bridge movements will result in operational problems elsewhere in the network At 2015, the increase in general traffic levels (independent of bridge operation) has resulted in problems in the operation of the Dudhope roundabout, leading to severe congestion throughout the Dundee city centre area It is considered that improvements could be made to the layout at the Dudhope roundabout to increase capacity. However, these improvements would not be required as a result of any changes to the operation of the toll bridge, and therefore have not been considered any further. Quantitative Assessment Tay Bridge Model 5.45 The following paragraphs describe the results of running the Tay Bridge models, in terms of providing a comparison of network journey times between the different scenarios. Tables 5.3 and 5.4 show the results for the AM and PM peak periods respectively in the 2010 scenarios, averaged in each case for 10 seeded runs In the AM Peak 2010 model, the removal of the tolls results in an increase in travel time for all northbound trips entering the network on the bridge. This is in line with the observations made in earlier in this section. All other travel times are generally unchanged between the two scenarios In the PM Peak 2010 model, the removal of the tolls also results in an increase in travel time for all northbound trips entering the network on the bridge. This is in line with the observations made earlier in this section. Journey times on the Inner Ring Road also generally increase with the removal of the tolls, again due to an increase in traffic levels. For all southbound journeys towards the bridge, journey times are decreased with the removal of the toll, due to the removal of delays and congestion on the approach to the toll plaza itself, despite the increase in traffic demand for these movements. 37

50 TABLE 5.3 AM PEAK AVERAGE JOURNEY TIMES IN THE TAY BRIDGE MODEL (IN SECONDS) AM Peak (08:00-09:00) Path ID Path Name 2005 Base 2010 With Toll 2010 No Toll Normal-Reassignment 2010 No Toll Reduced-Reassignment Time Time Diff Time Diff Time Diff 1 A85 Riverside Drive to Bridge A923 Lochee Road to Bridge A929 Victoria Road to Bridge A92 East to Bridge Bridge to A85 Riverside Drive Bridge to A923 Lochee Drive Bridge to A929 Victoria Road Bridge to A92 East Ring Road, Bridge to Dudhope roundabout Ring Road, Dudhope roundabout to Eastport roundabout Ring Road, Eastport roundabout to Bridge Ring Road, Bridge to Eastport roundabout Ring Road, Eastport roundabout to Dudhope roundabout Ring Road, Dudhope roundabout to Bridge

51 TABLE 5.4 PM PEAK AVERAGE JOURNEY TIMES IN THE TAY BRIDGE MODEL (IN SECONDS) PM Peak (17:00-18:00) Path ID Path Name 2005 Base 2010 With Toll 2010 No Toll Normal-Reassignment 2010 No Toll Reduced-Reassignment Time Time Diff Time Diff Time Diff 1 A85 Riverside Drive to Bridge A923 Lochee Road to Bridge A929 Victoria Road to Bridge A92 East to Bridge Bridge to A85 Riverside Drive Bridge to A923 Lochee Drive Bridge to A929 Victoria Road Bridge to A92 East Ring Road, Bridge to Dudhope roundabout Ring Road, Dudhope roundabout to Eastport roundabout Ring Road, Eastport roundabout to Bridge Ring Road, Bridge to Eastport roundabout Ring Road, Eastport roundabout to Dudhope roundabout Ring Road, Dudhope roundabout to Bridge

52 5.48 For differing reasons explained below, travel times within the 2015 scenarios are not tabulated. At 2015, in the AM peak, constraint on capacity on the northbound carriageway of the bridge and the downstream Riverside roundabout result in similar travel times for journeys across the bridge between the Existing Toll and No Toll scenarios, with vehicles queued on the south edge of the model In the PM peak, in both the No Toll and Existing Toll scenarios the network is predicted to experience significant congestion, particularly on the Inner Ring Road. This is generally due to background growth in traffic levels, rather than a direct function of the removal (or retention) of the toll charge. At the level of congestion experienced, it is difficult to ascertain a quantitative assessment of the relative levels of network performance between the two scenarios. However, given the general increase in traffic in the No Toll option, it can be expected that in reality, this scenario will result in a greater level of congestion in Dundee by 2015 than the Existing Toll option. Qualitative Assessment Forth Bridge Model 5.50 The following paragraphs describe the results of running the Forth Bridge models, in terms of providing a commentary of where operational problems were viewed. AM Peak 5.51 The 2005 base model experiences gridlock in the network to the north of the bridge, from around 08:20 to 08:30 onwards, depending on the random seeded value of the run. The source of the congestion within the network did not follow a common pattern, and could occur at a number of junctions within the modelled area. The gridlock of the model was also experienced in 2010 and 2015, for both the No Toll and Existing Toll options In some runs of the model, the gridlock appears to be initiated at Junction 1 of the M90, with vehicles on the southbound on-slip having difficulty in joining the southbound M90/A90 movement. This leads to a gridlock of the square of M90, A823(M), Queensferry Road and A985. However, in other runs, the problems commence at the downstream junction adjacent to the Park and Ride site, again with difficulties for traffic entering the southbound A90. This leads to problems on the east side of the M90 corridor, with gridlock more apparent around the B981 Hope Street and A921 Admiralty Road Another detail worthy of note is that the introduction of the new A8000 link road, and the consequent reassignment of traffic away from the existing A8000 Ferrymuir Road/B907 Kirkliston Road roundabout provides a general improvement in the operation of southbound movements over the bridge, although constraints further north within the model prevent the full benefits of the improvement being realised In all AM peak models, there are generally no problems for northbound traffic, except for later in the assessment periods when the general gridlock in the network begins to affect northbound traffic movements. 40

53 5.55 Consequently, due to the gridlock of the model, results for the full modelled period were not able to be generated for any of the scenarios, except for a minority of random seed values. It was not considered that this was acceptable in terms of the validity of any results obtained, and therefore further analysis was not carried out. PM Peak 5.56 The 2005 base model predicts queues on the approach to the toll plaza on the northbound carriageway of the A90. With the removal of the toll plaza, such queues are not generated. However it is noted that removal of the toll plaza (not represented in the model) would require re-design of the merge of the A90 and A8000 which occurs at this point; therefore any conclusions drawn in the vicinity of the toll plaza must be viewed with additional caution As a further trial, additional runs were generated for the No toll scenario, but with a toll delay retained to represent some form of metering on the northbound approach. The results show significant queues on the northbound approach, however, the model does not provide any additional insight into the operation of this section of the network that cannot be deduced logically from the TMfS data Due to the restrictions of the model outlined above, it was not considered appropriate to produce quantitative results for the PM peak period. Summary of Findings Tay Bridge 5.59 The following trends and conclusions can be drawn from the micro-simulation modelling of the Dundee area. In the AM peak, the removal of the toll results in a greater level of traffic on the bridge in both directions. In the northbound direction this leads to additional congestion on the approach to the Riverside roundabout resulting in queues back onto the bridge In the PM peak, the removal of the toll also results in a greater level of traffic on the bridge in both directions. The removal of the toll plaza reduces delay and queue lengths for vehicles approaching the bridge from the north, but increased demand for the movement also increases delay in other areas of the network. By 2015, the network is suffering from a significant amount of congestion due to the growth in traffic levels both with and without the removal of the toll A reduced-reassignment scenario was tested in which less traffic switched to using the bridge with the tolls removed. The results from these tests were not significantly different from the base reassignment scenarios; in both AM and PM peaks the impact of the reduced-reassignment scenario was within the limits of variation between the base model tolled and un-tolled scenarios Forth Bridge 5.60 Due to limitations of the model obtained from the previous SITCoS study, the results of the modelling does not provide any additional insight into the operation of the network that cannot be deduced from the changes in traffic flows from the TMfS output. 41

54

55 6. MODELLED IMPACT ON THE LOCAL ECONOMY Background to Dynamic Model 6.1 The Dynamic Model, has been developed by Steer Davies Gleave over recent years using System Dynamics modelling technology to help examine and explain the relationship between transport and economic activity in towns, cities and across regions. The modelling framework provides the means to model processes that are much harder to handle in traditional equilibrium models, particularly where feedback effects are concerned, such as the effect of congestion on travel conditions. 6.2 In the context of this study the Dynamic Model is being used to look at how changes in the toll on the Tay and Forth bridges affect costs of access, of the types described further below, and then to simulate how this might impact on economic activity as people and businesses adapt in response. While TMfS, in the way it was used in this study, provides the transport response to a change in toll, it will not tell us about the second order responses pertaining to individuals choice of where to live and/or work, and businesses decisions on where to invest or (re)locate. Results from this analysis are used to support the EALI analysis presented later in this report. 6.3 Transport provides access, and the impact of changes in transport costs on a local economy depends on how those patterns of access change, and then how people respond to those changes. The Dynamic Model constructs access measures that it uses to assess: Access of the workforce to employment Access of employers to a workforce Access of businesses to customers and suppliers (including retail and business to business) 6.4 If transport costs fall, then, all else being equal, the attractiveness of a location for business activity and as a place to live will rise. This will tend to increase inward migration of households or start-ups of new businesses to the point where other constraints such as the availability of suitable premises or of land provide a new limit. So in this study the model is used to assess how changes in the toll affect costs of access and then simulate how this might impact on economic activity as people and businesses adapt, in response. 6.5 The rest of this section provides: Further background to the Dynamic Model and its application to the Scottish Tolled Bridges Study A description of the data sources used in development of the model The interface with TMfS A description of tests undertaken relating to the tolls Results of the tests and commentary Scope of the Dynamic Model Overview 6.6 The Dynamic Model combines conventional transport modelling techniques with models of business formation, population migration and land-use, to provide a view on 43

56 how all of these factors work together and interact over time. Starting from a base year it moves through simulated time in small steps, calculating at each stage how events are likely to change. 6.7 In each application of the Dynamic Model the study area is divided into zones of varying sizes and within each zone it keeps track of the population, the businesses, the infrastructure and the land, and constantly assesses the attractiveness of each zone for business or residential use through simulated time as circumstances change, demonstrating how people respond, and, as a consequence, the transport conditions change further. A summary of the main tracked characteristics of each zone can be found in Appendix D. Zoning 6.8 The main initial task in the development of the Dynamic Model is the definition of the zones within a core study area. The requirement in this case was to choose an area that encompassed most of the commuter hinterland around the Forth and Tay Bridges. Given the wide geographic spread of business activities and trade, there are obviously practical limits to how far this can be taken. However access to a workforce is taken to be a significant factor in the choice of location, and is also a factor for which a great deal of supporting data is available via the travel to work census data. 6.9 In order to define the scope of the internal study area the travel to work movements were analysed between Scottish Council Areas in the context of interactions with the Tay and Forth bridges. The result was the identification of eight Council Areas to include in the internal study area. The rest of Scotland, with the exception of Argyll & Bute and the Highlands & Islands, was included in the Dynamic Model as buffer zones. The Council Areas included within the internal study area are: Edinburgh City West Lothian East Lothian Midlothian Dundee City Fife Perth & Kinross Angus 6.10 The next step was to define the zones within these Council Areas. The zones used in the Dynamic Model are necessarily aggregates of wards as much of the planning (economic and demographic) data is available at this level. The zoning has been constructed with reference to TMfS zones, which are generally more disaggregate, as it is necessary for us to construct a correspondence between the two zoning schemes for the purposes of providing the Dynamic Model with transport costs. Further details of the relationship between Council Areas, wards and zones can be found in Appendix D For the purposes of reporting the outputs from the modelling a set of aggregate reporting units at Council Area level have been defined, each formed of a number of Dynamic Model zones. These are shown in Figure 6.1 below. The solid black line shown around Angus, Perth & Kinross, Fife and the Lothians show the extent of the internal model area; the areas beyond this being defined as buffer zones. 44

57 Toll Impact Study Final Report FIGURE 6.1 DYNAMIC MODEL ZONES AGGREGATED TO REPORTING UNITS 45

58 Transport 6.12 Transport provides the links between zones, and in particular is the means by which employers gain access to employees, customers and suppliers. The Dynamic Model can represent zone-to-zone travel costs using either a link-based network, or tables of generalised costs This application of the Dynamic Model uses generalised costs for all the modes represented car, public transport (rail and bus) and active modes (walk/cycle) with the costs for road and public transport provided by TMfS. At the same time the Tay and Forth bridges have been explicitly included, as have some of the approach roads, as links within the model to allow modelling of congestion feedbacks Within the Dynamic Model an individual makes a decision, by evaluating the available transport options and costs, about whether to travel or not, then how far to travel to work within the model and consequently which mode to make that journey by. The interface with TMfS is described in more detail in paragraph 6.20 below. Attractiveness 6.15 The main dynamics in the model are created via the idea of the attractiveness of each zone for different types of activity. The model monitors each zone through time, and considers how attractive it is from four points of view: From the point of view of businesses and employers From the point of view of households From the point of view of developers, who build offices and other business premises From the point of view of house builders, who provide the housing 6.16 In general, the more attractive a zone is for an activity, the more that activity will take place, until new constraints limit further growth. Further description of how this works for each of the four bullets above can be found in Appendix D. In-Scope Movements 6.17 The current version of the Dynamic Model only deals with travel to work (commuter) trips. This is because its primary function was to look at the relationship between transport and economic activity while transport s contribution to the local economy is primarily through the way it gives employers access to a workforce, customers and suppliers. The ability to recruit is known to be one of the most important factors and the model addresses all of these, with a detailed simulation of recruitment and travel to work, while customers and suppliers are addressed via measures of proximity. It is not necessary to know the details of flows on networks split by time of day and purpose to do this. Therefore all the trip counts are for travel to work only. 46

59 Data Sources (Planning, Economic and Demographic) 6.18 As is evident from the discussion above the Dynamic Model needs a wealth of information about the initial conditions. The model is stocked with information about the population, businesses, housing and land for the base year. The data required can be summarised as: Population profile and economic activity: Households Total population/adult population/economically Active population Housing Business activity: Business Units and retail floor space Businesses by type Vacancy rates Planning: Land available/occupied by commercial and residential uses 6.19 Much of this data was procured from the General Register Office for Scotland, Scottish Executive, the Office for National Statistics (ONS) and Government departments including the Office for the Deputy Prime Minister (ODPM) and the Department for Trade and Industry (DTI). Further details about how the data assembly was carried out are provided in Appendix D. Interface with TMfS 6.20 The Dynamic Model uses changes in transport costs to predict changes in the local economy. TMfS provides the base generalised costs and changes in cost due to the removal of the tolls on the bridges For the modelling AM peak generalised cost matrices from TMfS were used. As noted in Section 4 the immediate impact of the toll removal will be a reduction in the cost of journeys over the bridge and an improvement in the journey time in the direction that the toll must be paid because of the removal of the toll collection. However, journey times will increase because of the additional congestion caused by the bridge s improved attractiveness. This reduces the demand, improving congestion and making the bridge more attractive again. The main mechanism that drives the changes in demand and subsequently costs in TMfS model runs is route choice, with a small amount of mode shift The TMfS generalised cost matrices for each of the model years (2010 and 2015) by model (road and public transport) were provided for all TMfS zone pairs. For use in the Dynamic Model it is necessary to generate generalised costs on the basis of the Dynamic Model zone pairs. To do this a correspondence list between TMfS zones and the Dynamic Model zones (this tended to be a many TMfS zones to Dynamic Model zone relationship) was established and a set of population based weights calculated to allow the calculation of a representative set of generalised cost matrices by mode for use in the Dynamic Model. Further details on the weighting process and production of the transport cost matrices are provided in Appendix D. 47

60 Description of Tests Undertaken 6.23 The following paragraphs provide some details relating to the validation of the Dynamic Model and the tests undertaken. Further details relating to the model validation are in the Appendix D. Model Validation 6.24 In order to determine that the Dynamic Model is fit for purpose a sequence of tests has been undertaken. These include: Ensure the model can generate the correct travel to work patterns, by mode, with fixed household and business numbers Validate against Census travel to work data Adjust mode choice and deterrence function parameters Check that when the migration and business startup/closure processes are turned on it can replicate the base year figures correctly Households by type Businesses and jobs by type The model is run to 2005 and checked that it can replicate what is known to have happened over the intermediate years looking at Households Businesses and jobs Travel to work patterns Travel to work mode shares 6.25 It should be noted that the travel to work matrices are generated by the Dynamic Model rather than being an input, being generated by the interaction of the workforce (by residential zone) and businesses (by work zone) which are linked through the transport opportunities. The observed matrices are used to calibrate the mode choice model together with the base year TMfS generalised costs. Model Scenarios 6.26 A number of scenarios have been modelled: Reference case (maintaining the toll at existing level on both bridges) Removal of tolls from both Forth and Tay bridges Removal of tolls from both Forth and Tay bridges (reduced-reassignment assumptions) Removal of toll on Forth Bridge only Removal of toll on Tay Bridge only 6.27 A sensitivity test has been undertaken with double tolls on both Forth and Tay bridges. The results of this test are presented in Appendix D. In the no tolls model run we have also taken into account information from the local traffic modelling. 48

61 Results and Commentary 6.28 As noted above the main tests undertaken with the Dynamic Model have looked at the complete removal of the toll on the Forth and Tay bridges as compared against the retention of tolls at existing levels. The effect of the removal of the toll, in transport terms, on the cost of travel is mitigated by increased "congestion" and so the actual travel time element of the generalised cost increases but in most cases does not outweigh the reduction in costs from the removal of the tolls The key indicators in terms of the economic impacts of the removal of the toll relate to the numbers of jobs and people in the workforce. Businesses may open in certain areas taking advantage of a more attractive business environment partly due to there being a more accessible labour force to recruit from, through reduced transport costs. At the same time people perceive the area as a more attractive place to live and work and there is inward migration partly due to having a more accessible range of jobs. These effects obviously vary across the study area according to the relative changes in the transport costs and in addition to net generation there would also be redistribution as businesses may close in one area and move to another to take advantage of the more attractive conditions Additionally the extent to which the change in the transport costs can help vacancies to be filled and more people to get into employment as people and jobs are brought into closer proximity is important ie more jobs are filled and vacancy rates reduced which in turn can increase the business attractiveness and stimulate further growth. Also more residents have the opportunity to get into employment, some residents can take advantage of opportunities that were previously too far away and this can create vacancies that can be filled by others over time. For example as the cost of travel between Fife and Edinburgh is reduced due to the removal of the toll then more Fife residents will be able to travel to those jobs in Edinburgh and so the proportion of residents working in Fife will reduce. Again the effects expected are a mixture of generation and redistribution Linking these all together and driving them are the flows and changes in distribution as the travel to work patterns change and this is demonstrated in the results where with the removal of the tolls there are more trips between areas which would involve the use of the bridges. The effects are a mixture of new jobs, workforce and redistributed jobs and workforce and changes in peoples' places of work and residence over time Table 6.1 and Table 6.2 present summaries of the results from the no tolls model runs from the base case and reduced-reassignment model runs (including the link with Paramics) which illustrates all of the above effects. This presents, by each Council Area, the change in the number of jobs/jobs filled and people in the workforce 4 (and in employed residents). The number of jobs represents the number of posts which may or may not be vacant and jobs filled represents the number of jobs which are occupied. 4 Economically active population 49

62 TABLE 6.1 CHANGE IN KEY INDICATORS BETWEEN NO TOLLS AND TOLLS MODEL RUNS (BASE CASE) 50

63 TABLE 6.2 CHANGE IN KEY INDICATORS BETWEEN NO TOLLS AND TOLLS MODEL RUNS (REDUCED-REASSIGNMENT ASSUMPTIONS) 51

64 6.33 The tables also shows the change in the total number of trips and the change in the distribution of the destinations of those trips by broad area (within the same area, elsewhere within the core study area and external to the core study area) and in particular shows the changes in the number of trips originating in these areas travelling to jobs in Fife, Edinburgh City and Dundee It should be noted that the business and other dynamics are switched off in the external/buffer areas which means that the numbers of businesses/jobs and households/workforce are held constant accounting for the numbers of jobs and workforce being unchanged in these areas 5. However whether those jobs are filled or not depends on where residents decide to work influenced by the changes in transport costs and so the level of employment by area for both residents and businesses can vary across the whole study area. Table 6.3 shows an aggregated matrix of the changes in travel to work trips between the two model runs, again for the base and reducedreassignment models The general direction and patterns of change in both model runs, with respect to the with tolls base case, are the same, although the magnitudes differ principally as a result of the difference in the transport costs in the two scenarios. As the results are not significantly different the general commentary below focuses on the base case model run. TABLE 6.3 Base Reassignment Run CHANGES IN TRAVEL TO WORK TRIPS BY AGGREGATE AREA BETWEEN NO TOLLS AND TOLLS MODEL RUNS Zone Name Edinburgh City Midlothian West Lothian East Lothian Fife Perth and Kinross Dundee City Angus External Total Edinburgh City Midlothian West Lothian East Lothian Fife ,178 Perth and Kinross Dundee City Angus External Total The reason for this is to avoid model boundary effects. Zones close to the edge of the model have only part of their catchments represented, so if employers there find it harder to recruit from the internal area, say, they will suffer more in the model than they might in reality because in practice they could seek to recruit from zones excluded from the model. 52

65 Reduced-Reassignment Run Zone Name Edinburgh City Midlothian West Lothian East Lothian Fife Perth and Kinross Dundee City Angus External Total Edinburgh City Midlothian West Lothian East Lothian Fife ,265 Perth and Kinross Dundee City Angus External Total On the workforce side across the study area as a result of removing the tolls there is a combination of a (relatively) small net in-migration of workforce together with redistribution between zones. Fife is the primary beneficiary from this process. The largest increase in residential workforce is in Fife, 1,178, which is of the order of 0.5% (which appears to be at least partly driven by people re-locating from south of the Forth - Edinburgh, West and Mid Lothian) followed by Perth and Kinross. The residential workforce in the areas south of the Forth decline marginally - approx -0.1 to -0.3% In terms of parts of the workforce there is a slightly bigger impact on the skilled workforce, as these are the members of the work force who tend to be more mobile and to be most sensitive to changes in cost of travel, and hence the removal of the toll. However there is also an impact on the lower skilled (manual) part of the workforce. The removal of the tolls also helps more residents to get into employment and again Fife residents are the primary beneficiaries with 1,178 additional residents getting into work and 903 more Fife residents finding employment in Edinburgh City. This is partly due to some Fife residents travelling to other areas with the vacancies being filled by other Fife residents Accordingly there is an increase in the residential workforce in Fife; in addition, unemployment rates fall marginally as the reduction in transport costs means that some vacancies can be filled. There are therefore more people travelling to work (employed residents). In addition to there being a net increase in trips originating in Fife there is a change in the distribution, with an overall reduction in the trips within Fife (-553), and an increase in trips to Edinburgh (+903), and to a lesser extent the Lothians and to Dundee (but about half the increase there is to Edinburgh). In the reverse direction there is some increase in trips from Edinburgh/West Lothian and Dundee to Fife but these increases are much lower than the outflows from Fife across the Forth and Tay bridges. Figures 6.2 to 6.4 below show the change in the number of trips from each of the aggregate areas to Edinburgh, Dundee and Fife respectively. 53

66 6.39 Figure 6.2 shows an overall slight increase in the number of jobs in Edinburgh that are filled and at the same time a greater number of the jobs are filled by Fife residents, as the cost of travel reduces with the removal of the toll. Figure 6.3 and Figure 6.4 show similar effects for Fife and Dundee with more people travelling to these areas for work this is balanced by more residents of these areas travelling out to neighbouring areas. In general what we are seeing is a geographical expansion of the labour market with the pool of labour for jobs widening and at the same time the workforce has access to more jobs with the focus of these effects being on the Edinburgh Lothians Fife Dundee axis, with less jobs being filled by local residents of each respective area. However the effect on the overall economy in terms of net additional jobs is marginal In terms of jobs, the analysis distinguishes jobs as demand for labour and jobs actually filled. Overall, in the internal study area, there is a slight increase in jobs but a greater increase in the number of jobs filled the reduction in transport costs making recruitment easier. The changes in travel costs affect where people choose to work and live, and therefore affect recruitment rates, and hence jobs filled, in different areas. This is because travel costs are lower between some places and higher between others. The outcomes in terms of filled jobs, which takes recruitment effects into account, is to increase the numbers of jobs filled in Edinburgh, Fife and Dundee. The net effect on the internal study area is an increase in filled jobs. The effect is, however, negligible in relation to the overall size of the labour market The effect on mode shares is negligible overall across the study area as a whole with a slight movement in favour of car at the expense of active modes. This is not surprising and the small mode shift is consistent with the outputs seen from TMfS. What this represents is that trip lengths from some areas (for example Fife) increase due to the reduction in travel costs to areas south of the Forth and north of the Tay, which means that residents in Fife, for example, have a bigger pool of jobs that they are able to access. The size of the shift does vary by area though, due to the differential effects of the removal of the toll on the travel costs and consequently labour market access. 54

67 FIGURE 6.2 CHANGE IN TRAVEL TO WORK MOVEMENTS TO EDINBURGH BY ORIGIN AREA (BASE CASE) 55

68 FIGURE 6.3 CHANGE IN TRAVEL TO WORK MOVEMENTS WITH FIFE AS DESTINATION BY ORIGIN AREA (BASE CASE) 56