Bromley Town Centre. Transport Strategy Supporting the Area Action Plan. Evidence Base

Transcription

1 Bromley Town Centre Transport Strategy Supporting the Area Action Plan Evidence Base Produced on behalf of London Borough of Bromley by Peter Brett Associates LLP April 29

2 Bromley Town Centre AAP Evidence Base Evidence Base We print on 1% recycled paper from sustainable suppliers accredited to ISO 141. X:\Evidence_Base_2959_FINAL.doc ii

3 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 1 Introduction The development of the AAP and Bromley Town Centre Transport Strategy has been progressively informed by modelling and strategic study work. This note describes the work undertaken and conclusions reached which have been encompassed within the AAP and Transport Strategy As part of developing the evidence base, modelling work was undertaken by Hyder in 26 and 27 (which culminated in the modelling runs of Spring 27) to examine the town centre wide impacts of the development options being considered for the various opportunity sites at that time Subsequently the Hyder modelling and trip generation has been reviewed by Savell, Bird and Axon (SBAx) in 28, to take into consideration the revised quantum of development that emerged through the AAP proposals including the Site G proposals. The modelling took into account the emerging Transport Strategy including changes to the provision and management of parking, as well as improvements to public transport, walking and cycling within the town centre. Mitigation measures such as junction improvements at Mason s Hill have also been assessed. The development quanta considered as part of this process are given in Table 1. Table 1: AAP Development Quanta Land Use Modelling Spring 27 (Hyder) Modelling 28 (SBAx) Residential (units) Office (sq m) 9 7 Retail A1 GFA (sq m) Retail A3-5 GFA 9sq m) Community (sq m) 3 2 Leisure (sq m) 4 4 Hotel (rooms) Health (sq m) The two stages of modelling work have been supplemented by further strategic study work undertaken by PBA. Taken together the modelling and strategic study work has informed the preparation of the Transport Strategy which underpins the proposals in the AAP This report provides a summary of the work undertaken by Hyder and SBAx and the further strategic study work undertaken by PBA that underpins the AAP Transport Strategy. The report therefore forms the evidence base for the Transport Strategy and consists of the following sections: Section 2 summarises the work undertaken by Hyder in 26 and 27; Section 3 summarises the work undertaken by Savell, Bird and Axon in 28; X:\Evidence_Base_2959_FINAL.doc iii

4 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Section 4 examines the peak hour development trips and how these have been refined since 27. It also discusses the retail trip estimation and parking underutilisation; Sections 5 and 6 examine the proposed mitigation measures that will be implemented to ensure that the target for a ten percent reduction in traffic levels by the end of Phase Two ( ten in ten ) is met. Section 5 deals with Parking policy and Section 6 looks at travel plan measures; Section 7 discusses the effect of the revised development trips on the highway network, and changes to mode split; Section 8 discusses the targets set for the AAP and how they relate to the trip generation; Section 9 provides a conclusion summarising the work undertaken and how this has informed the development of the Transport Strategy. X:\Evidence_Base_2959_FINAL.doc iv

5 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 2 Hyder Traffic Modelling In 26 and 27 Hyder undertook extensive modelling using the Paramics micro simulation model of Bromley Town Centre on behalf of LB Bromley and Transport for London. This modelled the development quantum at this time, which is set out in Table 1. The modelling work is described in a suite of reports which provide the results of runs in 26 and 27 (Appendix A) The development trips used in the model were provided by PBA. To calculate the trip generation a managed approach was adopted assuming that the existing underutilisation of some town centre car parks can be used to serve the new developments. It was also assumed that car parking provision would be constrained to the maximum levels as in the UDP standards of that time Trip generation figures not taking into account a managed approach would have been calculated from the trip databases (TRICS or TRAVL) recognising that there would be a tendency for the usage of the generous parking provision to reflect past trip making profiles for individual sites. This approach involves multiplying typical trip rates by the GFA of the development. It would not however reflect the potential for the parking to serve the town centre as a whole and linked trip making within the town centre. This could therefore lead to an overestimation of the additional flows to the new development For the Managed Approach trips were calculated from trip rates derived from current usage of Bromley town centre car park spaces. This approach was adopted in preference to using rates based on individual sites. Using trip rates based on the usage of existing spaces provided a robust approach which accords with the current pattern of flows into the town centre car parks For other non-retail developments proposed in the AAP, typical trip rates were selected from databases that are appropriate for developments located in areas of high public transport accessibility The total trips calculated for the new developments were added to the 24/5 base case flows, and the total flows used in the modelling examined the overall traffic impacts of the development proposals. This approach therefore did not take account of traffic flows into the town centre in previous years, prior to the closure of two large departmental stores, which would have been higher than the base case flows The inputs to the modelling therefore assumed that trip making reflected current patterns of movements for the development scenarios based on parking provision for the new developments which accord with the maximum levels given in the recently adopted revised UDP standards. These levels take account of the high public transport accessibility within the town centre The modelling approach did not consider the impact of potential changes to general traffic levels in Bromley during the time horizon of the AAP or whether further policy led initiatives X:\Evidence_Base_2959_FINAL.doc 1

6 Bromley Town Centre Transport Strategy supporting AAP Evidence Base could further influence the quantum of traffic generated by the proposed developments The modelling undertaken by Hyder considered the impact of development scenarios from higher levels of retail floor space (49,5 sqm) through to lower levels (25,5 sqm), with different assumptions tested on the phases for development The AAP development process was taken forward in an evolutionary way with modelling considering the traffic impacts of development sites and additional parking being placed at various locations. The modelling assisted in demonstrating that the traffic impacts of placing further larger scale retail development and associated parking in the north of the town centre were unacceptable. This led to examining the potential of placing the major retail expansion in the south of the town and at the Pavilion site The primary conclusion of the modelling was that only a very modest increase in retail was possible without the need for mitigation measures. It would be possible to accommodate about half of the original 5, sq. m (GFA) planned expansion development, but only with widening of the A21 on the approaches. Further mitigation measures were also modelled involving traffic management measures such as further adjustments to signalling, physical changes such as lane allocation at junctions, and changing signal priorities. In order to avoid junction operational problems at Bromley South, the modelling at that stage also assumed that the bus gate at the Elmfield Road/ A21 Kentish Way junction be removed to enable traffic to access the proposed Site G development car park directly from this junction with the A These measures relieved some of the congestion problems but the modelling showed significant delays still occurring on the southern approaches to the town centre. These delays tend to create a ripple effect with queuing building to cause congestion problems at junctions along the A21 through the town centre. The traffic modelling showed network delay substantially increased even for development scenarios incorporating the lower levels of retail development The further highway mitigation measure involving widening of the A21 to two lanes each way between Kentish Way and Bromley Common when considered for the lower levels of retail floor space was shown to largely reduce congestion back to base levels. The test employed was one of nil detriment, in other words whether mitigation measures can return traffic delays to base levels The modelling therefore showed that with reliance placed on highway and traffic management measures alone, retail development of up to 25,5 m 2 GFA could be accommodated. This would require substantial highway mitigation works including the widening of the A21 southern approaches. The modelling also indicated that some problems remain at particular junctions and there are some further delays above base levels on certain bus routes. Hence further traffic management measures, particularly bus priority measures to protect and enhance service provision would also be needed to accompany the mitigation measures that have been modelled These results therefore suggest that there is limited capacity in the town centre network to X:\Evidence_Base_2959_FINAL.doc 2

7 Bromley Town Centre Transport Strategy supporting AAP Evidence Base accommodate additional traffic measures above the levels that have been modelled, even with physical mitigation measures, including the A21 widening. Consequently, no further Paramics modelling work was undertaken to test for additional traffic from higher levels of retail development. Moreover this highlighted the requirement for other forms of mitigation (i.e. measures not just limited to highway and traffic management) needed to be considered which would reduce traffic increases and thereby enable higher levels of retail development to be accommodated as proposed in the AAP It should be emphasised that the conclusions from the Paramics modelling were largely driven by and dependent upon the assumptions built into the modelling approach. These did not take account of the following: Broader policies changes (influenced by national, regional or GLA agenda); A comprehensive set of local policy initiatives set within a sustainable transport strategy (i.e. a Transport Strategy for Bromley Town Centre); The potential broader based set of mitigation measures that would be needed to address the traffic impacts of developments and accommodate further growth This underlined the need to develop the Transport Strategy to address the development impacts and promote the mitigation measures needed to accommodate the growth proposed within the AAP for the town centre. X:\Evidence_Base_2959_FINAL.doc 3

8 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 3 Savell Bird & Axon Report In 28 SBAx, on behalf of LXB Properties (LXB), prepared a Transport Statement to establish the transport implications of the proposed comprehensive redevelopment of Sites G, H and N of the Bromley AAP. The full report is contained within Appendix B. As part of their work SBAx reviewed the 27 Hyder Model and refined the trip generation for the AAP based on the quantum of development that is now being proposed in the AAP. In addition a parking assessment was carried out to establish car parking utilisation and spare capacity during the three phases of the AAP The underlying conclusion from the 27 modelling was that, with junction improvements and the widening of the A21, the development quantum assumed for the medium term of the AAP could be accommodated. However, the adoption of the town centre transport strategy, offered the potential for larger development quantum being acceptable in the longer term. The successful implementation of the transport strategy might also lead to the reconsideration of some of the modelled junction or highway improvements The modelling work undertaken in 28 placed reliance on taking forward an approach for the town centre which would restrain overall traffic levels, including that generated by the new developments. This would encompass a parking strategy that would utilise the existing parking stock more efficiently with a degree of parking constraint particularly for non-retail uses. This would be combined with encouragement of walking and cycling for local trips and improvements to public transport, backed up by travel planning and other soft measures. This approach helped inform and support the emerging Transport Strategy for the town centre The modelling work examined the traffic impact the Site G proposals of placing a 6 space retail car park in the south of the town centre, with a further 6 space residential car park. A more refined approach was adopted for determining trip generation from this development and the rest of the developments proposed within the AAP for the town centre. The trip generation assumed for the previous modelling was considered robust and suitable for strategic modelling purposes, but it was also accepted that these values could be further refined and thereby reduced It should be noted that the 27 Paramics model incorporated highway and traffic mitigation measures such as the removal of the Elmfield Road bus gate. However with further consideration with the AAP process, the removal of the Elmfield Road bus gate was not at this later stage viewed as an acceptable mitigation measure for the AAP, given its importance for providing bus priority within the town centre. The developer decided that there was little to be gained by running the Paramics model again and instead opted for undertaking junction modelling Junction modelling for the south of the town centre using LINSIG was undertaken. This showed that by increasing the capacity of these junctions they should be able to accommodate the traffic generated by the Site G development. This would obviate the need to remove the Elmfield Road bus gate. X:\Evidence_Base_2959_FINAL.doc 4

9 Bromley Town Centre Transport Strategy supporting AAP Evidence Base The SBA trip generation model forecast that 645 two-way vehicular trips will be generated by the Phase 1-3 AAP sites during the weekday PM peak hour compared to the original forecast of 674 two-way vehicular trips used for the Hyder traffic model in The SBA trip generation model forecast that 825 two-way vehicular trips will be generated by the Phase 1-3 AAP sites during the Saturday peak hour compared to the original forecast of 1129 two-way vehicular trips used for the Hyder traffic model in 27. Therefore SBAx concluded that the cumulative impact of the AAP development was less than stated in the Hyder report. SBAx stated this was a result of changes to the AAP proposals since the modelling was undertaken in 27 and also a more refined trip generation model that takes account of the complexity of trip making in mixed use town centres To assess the spatial effects of the AAP, a capacity assessment using LINSIG was undertaken by SBAx on the following junctions: o Westmoreland Road/Westmoreland Road car park (signal controlled) o o o Westmoreland Road/Sandford Road (priority junction) Masons Hill/High Street (signal controlled) Masons Hill/Kentish Way (signal controlled) The junction of Masons Hill/High Street was modelled using the proposed junction improvement as part of the AAP. This improvement includes widening the Westmoreland Road arm to provide two lanes and a right turn flare and a change to the pedestrian crossings from direct to staggered crossing facilities. The modelling used the Hyder 24/5 base flows and added on the AAP development traffic flows as calculated by SBAx The results show that after the development trips have been added the Practical Reserve Capacity (PRC) over all links in the junctions is 4.9% in the Weekday PM peak and 4.1% in the Saturday peak. Therefore the modelling concluded that the junctions will operate within capacity with the AAP development traffic. The full results from this assessment are contained within the SBAx report in Appendix B An assessment of spare parking capacity was also undertaken. This showed that there is sufficient capacity to cater for the existing and AAP parking demand Therefore, in modelling terms, the evidence base encompasses the results of the earlier Hyder work, using Paramics modelling to examine town centre wide traffic impacts, and on the localised junction modelling undertaken by the developer of Site G. Taken together the modelling has shown that the medium term developments can be accommodated by making highway and traffic management improvements. X:\Evidence_Base_2959_FINAL.doc 5

10 Bromley Town Centre Transport Strategy supporting AAP Evidence Base It should be emphasised that the Hyder and SBAx modelling work has been undertaken assuming that development flows are added to the 24/5 base case flows on the town centre network. Traffic reductions that have been counted on the network since 21, through 24/5 and subsequently have not been considered. This factor alone should provide some further capacity in the network to accommodate the AAP longer term development proposals The AAP, however, provides the opportunity to present a much more detailed and comprehensive description of what the town transport strategy would entail. Further evidence base supporting work has been undertaken to look at how the Transport Strategy could mitigate against the traffic impacts of the longer term AAP development quantum as a whole The extent of potential trip generation from the developments will be influenced by the degree of utilisation of town centre car parking. This important aspect is further discussed in the next section of this note The remaining sections of this note considers the further reductions that should occur with the implementation of the town centre strategy (including the proposed Ten In Ten strategy), and also examines the significant impacts of overall traffic reductions in traffic levels that have occurred since the data was collected for the traffic modelling. X:\Evidence_Base_2959_FINAL.doc 6

11 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 4 Peak Hour Development Trips For the Hyder 27 modelling, robust trip rates were provided by PBA when deriving trip generation numbers for the development proposals. Subsequently a more refined approach was adopted by SBAx in 28 to assess the AAP development quanta including Site G proposals. The vehicle trip generation numbers for both the Hyder and SBAx work are summarised in Table The full calculations for the trip generation used in the Spring 27 modelling can be found in the Hyder Reports (Appendix A). The full trip generation calculations for the AAP including Site G work can be found in the SBAx report Bromley Town Centre Site G transport Statement (Appendix B). Table 2: Vehicle Trip Generation for Hyder and SBAx Work Land Use Two-way development trips used for modelling Weekday PM Peak 17: 18: Saturday Midday Peak 12: 13: Modelling Spring Modelling 28 Modelling Spring Modelling Residential Retail Other Total The weekday peak PM vehicle trips calculated in 27 and 28 are broadly comparable. However it should be noted that the Site G modelling encompasses a far greater retail floor area, and it would have been expected that the level of trip making would be greater For the Saturday peak hour ( ), there are substantial differences for all land uses Considering these differences it is therefore appropriate to review the trips for the 28 development quanta New data has been obtained showing the current utilisation of the Multi-story car parks. This has enabled the trip generation from the retail development (as presented by SBAx) to be revisited and trip numbers associated with Phase 2 (which concern the Site G development) and Phase 3 (which incorporates the main department store on Site G and further retail development on Site G and Site E). The major development on Site E could lead to greater use of any underutilised car parks in the town centre, particularly on a weekday A simplified method for calculating retail trips, taking into account underutilisation is given in Appendix C Background to Retail Trip Calculations. The SBAx methodology for calculating trip rates for residential and other land uses is thought to be more representative than that deployed for the 27 Hyder work which is now thought to produce unduly high trip flows particularly on a Saturday. X:\Evidence_Base_2959_FINAL.doc 7

12 Bromley Town Centre Transport Strategy supporting AAP Evidence Base The reworked two-way trips for retail and those obtained from the SBAx work for residential and other land uses are given in Table 3. Table 3 Reworked Two way trips for latest AAP Proposals Land Use Reworked Two-way development trips Weekday PM Peak 17: 18: Saturday Midday Peak 12: 13: Phase 2/ early End Phase 3 Phase 2/ End Phase 3 Phase 3 early Phase 3 Residential Retail Other Total From Table 3, it can be seen that the increase from phase 2 to phase 3 for the weekday PM peak is twice the increase on a Saturday. This reflects the circumstance that on Saturday the existing multi-story car parks are generally well utilised and that the move from Phase 2 to Phase 3 with additional retail on Site E results in a proportionally smaller increase in car trips. For the weekday however there is greater underutilisation of car parks and hence a greater potential for trip making A comparison of Table 3 with Table 2 shows that the Spring 27 modelling for Saturday employed a significantly greater figure than the reworked trip number for Phase 3. The Site G 28 modelled figure however has a very similar figure to the reworked Phase 3 figure For the weekday PM peak, the 27 and 28 modelled figures are just slightly greater than the phase 2 reworked trip numbers. But the reworked phase 3 number exceeds the modelled figures The modelling undertaken to date therefore covers the range of flows likely to be generated by the Phase 2 and Phase 3 developments for Saturday peak flows which was the critical case for AAP assessment. For a weekday however the modelled flows are less than those derived assuming greater utilisation of the spare spaces in the town centre car parks. This aspect is explored in the following section. 4.2 Retail Trips and Parking Underutilisation As previously mentioned, the Site G modelling figures for retail trips have been derived using a more refined methodology, as described in the SBAx report (Appendix B). The SBAx methodology produces very similar results to the simplified approach by PBA for the Saturday peak. There is however a significant variation for a weekday Table 2 gives 385 two-way retail trips for the weekday PM peak (end of Phase 3) while Table 3 gives 595 trips i.e. a difference of 21 trips The explanation for the difference is the assumptions made concerning the potential use of underutilised car parking spaces on a weekday. The SBAx methodology assumes that overall trip making will not be influenced by an excess in the availability of underutilised spaces. X:\Evidence_Base_2959_FINAL.doc 8

13 Bromley Town Centre Transport Strategy supporting AAP Evidence Base SBAx have however undertaken a detailed review of the overall underutilisation of car parks on a Saturday and weekdays, and how they will change through the various development phases. These results are shown in Figures 1 and 2 below. Figure 1: Saturday Utilisation of Car Parks Existing End of Phase 1 End of Phase 2 End of Phase 3 Maximum Number of Car Parking Spaces Maximum Usage Figure 2: Weekday Utilisation of Car Parks Existing End of Phase 1 End of Phase 2 End of Phase 3 Maximum Number of Car Parking Spaces Maximum Usage For Saturday it can be seen from Figure 1 that the existing substantial underutilisation is progressively diminished with increased retail trip making with only a marginal number of spare spaces available by the end of the AAP time frame. There is therefore no scope for X:\Evidence_Base_2959_FINAL.doc 9

14 Bromley Town Centre Transport Strategy supporting AAP Evidence Base additional trip making. The simplified PBA methodology also took on board these circumstances, and the retail trips calculated by both PBA and SBAx are similar, confirming the robustness of the calculations For a weekday Figure 2 shows there is some reduction in underutilisation over the AAP period with the existing underutilisation of 962 reducing by 318 to 644 in Phase 3. The PBA simplified methodology assumes that 672 of the underutilised spaces in the Glades and Civic Centre would be used by the expanded retail offer. However if the PBA methodology is applied to the 318 figure (rather than 672) the resultant two-way retail trips would be 443, only slightly above the 385 trip figure from the SBAx work given in Table 2. The difference in the weekday retail trips derived from the two methodologies is therefore directly related to the degree of use of currently underutilised car parking spaces It may be the case that the SBAx methodology adequately represents the degree of parking demand and take up of underutilised car parking. However, other strategies may also need to be taken forward to ensure that if there is a greater propensity to use these spaces, the amount of trip making associated with accessing those spaces during peak hours is kept to a minimum The evidence base includes a section that looks at the impact of modal change on vehicle trip making. For the purposes of these calculations the higher reworked retail trips for the weekday peak have been used as these represent the worst case. X:\Evidence_Base_2959_FINAL.doc 1

15 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 5 Ten in Ten: Parking Policy and Traffic Levels 5.1 Introduction The following two sections deal with the mitigation measures that are likely to be implemented in Bromley Town Centre to achieve the ten in ten target. The ten in ten target looks towards reducing the modal share of travelling by car by one tenth within ten years. This is equivalent to reducing the level of trip making by car after allowing for future traffic growth in the town centre by 1% within 1 years. This section deals with parking policy and traffic levels whilst Section 6 looks at travel plan measures for the town centre and the percentage reductions of car traffic that could be achieved. 5.2 Key Initiatives This section concerns the LB Bromley s policies and their potential impact on traffic levels within the town centre. Primarily these concern the application of parking levels for new developments and would be aimed at supporting Objective 4. The approach involves considering the town centre parking provision as a whole and the utilisation of the public parking to serve uses throughout the town. There are other aspects of parking that could further assist meeting a number of the objectives and these are considered as part of the development of a parking regime for the town centre as described in the Transport Strategy. This section considers the policies considered when deriving the trips generated by developments and used for modelling purposes or deriving overall traffic level changes in the town centre. The potential for achieving further reductions in traffic levels by adopting further specific parking policies, as part of the Transport Strategy ten in ten approach is also examined. 5.3 Retail Car Parking Levels The amount of parking provision made available in the town centre to serve the new developments will have a major impact on the volume of generated traffic accessing the town. The modelling using base data from 24/5 has shown that the performance of the network is sensitive to relatively small changes in flows. However the town centre network in the five years prior to 25 operated at around a 5% higher level. Subsequently there have been further significant reductions in traffic. This shows that there is some reserve in the network to accommodate the further flows associated with additional retail activity above the modelled base case In undertaking the modelling it has been assumed that the adopted UDP standards would apply for the new development. For retail a ratio of one parking space per 5 m 2 and 75 m 2 GFA have been considered. For residential developments the level of car parking and trip making has been related to urban areas having high public transport accessibility. It is proposed that parking levels should not exceed.5 spaces per unit. With the exception of leisure (cinema) uses, for other uses the extent of additional trip making is largely negligible. Specific parking is not to be provided for leisure, with the assumption that existing town X:\Evidence_Base_2959_FINAL.doc 11

16 Bromley Town Centre Transport Strategy supporting AAP Evidence Base centre public parking will be used The range of retail GFA that has been considered during the preparation of the AAP has been between 49,5 m 2 and 25,5 m 2, and the total new retail area now proposed is 42, m 2. Thee totals should be compared with the base floor area of 115,2 m 2. The parking for the new development has been assumed to be provided either by the deployment of currently underutilised spaces or a new car park (6 spaces) for the development on Site G, although either approach results in additional flows on the network. It would be possible to reduce the number of new spaces made available by applying the lower ratios given in the UDP for locations in town centres having high public transport accessibility. A further possibility is to limit the impact of new parking provision by balancing this with reductions elsewhere within the AAP it is proposed to reduce the parking provision at Westmoreland Road car park by 181 spaces.. The resultant changes to parking ratios for these possible options are given in Table 4 below: Table 4: Impacts of parking reduction for 42, m2 of retail development Retail Parking Space Ratio GFA in New Parking Level assumed for new Town Spaces retail development Centres Total Spaces in Town Centre (Saturday) Overall Parking Space Ratio in Town Centre Base Level 115,2 n/a :24 Upper UDP Ratio 151,2 1: :27 A new car park on Site G 151,2 1: :28 Lower UDP Ratio 151,2 1: :28 AAP Proposal: A new car park on Site G and a reduced car park for Site K No Additional Parking 151,2 1: :29 151,2 n/a :31 X:\Evidence_Base_2959_FINAL.doc 12

17 Bromley Town Centre Transport Strategy supporting AAP Evidence Base From the above tables it can be seen that reducing the number of new spaces has a modest impact on the overall town centre parking ratio. This is because the existing town centre parking provision is reasonably generous and this is underlined by the degree of underutilisation of some of the car parks, particularly on a weekday When considered on a town centre wide basis, the AAP proposal for new parking provision serving the overall 42, m 2 retail development can be seen to provide a parking space ratio of 1:1, which is significantly less than the 1:5 and 1:75 ratios. Again it is necessary to opt for a reduced town centre wide ratio, given the current underutilisation and also to avoid generating significantly greater levels of traffic It could be argued that adopting a restrictive retail parking policy provides an opportunity to substantially diminish the increases in flows into the town centre generated by developments. However given that the degree of underutilisation of parking in the town centre, particularly on weekdays, there will be a propensity to greater use of these empty spaces, even after taking into account increases in trip linkage and dwell time. Inevitably this will still lead to some increases in traffic flows. The traffic impact of this greater use is considered later in this section. 5.4 Residential Car Parking Levels For new residential development it would be possible to further decrease flows into the town centre taking into account the high public transport accessibility by adopting a no car housing policy. This would be particularly appropriate for opportunity sites located at or near the two stations, but a global policy of limited car parking for all new residential development could also be considered given that the PTAL levels of 6b apply across the town centre The adoption of car free parking policies can be assisted by the adoption of car clubs which would permit access to cars and other soft measures described in the transport strategy In terms of meeting Objective 3 and 4, it would be essential that restrictions are in place to prevent parking on street. Parking restrictions are likely to require extending CPZ s geographically to prevent the new occupants from seeking parking some distance from their homes and competing with existing residents for kerb space. This approach would also require that the residents of the car free developments are not permitted to acquire resident s parking permits and thereby restrict them from parking in controlled parking zones These measures will need to form part of a parking plan for the town centre as described in the Transport Strategy. 5.5 Retail Car Parking Levels and Traffic Flows The overall increase in flows within the town centre for the proposed retail developments (42, m 2 ), and the percentage increase over base level flows are given in Table 5 and 6 below for Saturday and Weekday peaks respectively. The retail figures are from the PBA methodology (see Appendix C Background to Retail Trip Calculations) X:\Evidence_Base_2959_FINAL.doc 13

18 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Table 5: Modelled Increases in Traffic Flows (Saturday Peak) Phase 2/ Early Phase 3 End Phase 3 Land Use Hourly Saturday Peak Two-Way Traffic Flows % Increase Relative to Total Base Levels Flows Hourly Saturday Peak Two-Way Traffic Flows % Increase Relative to Total Base Levels Flows Retail % 63* 6.2% Residential % % Other 34.4% 34.4% Total % % Note: Percentage traffic flow increases are relative to 24/5 base levels. *It is assumed that the majority of town centre parking is fully utilised on a Saturday and just the spare spaces in the NCP car park will attract further parking at Phase 3. Table 6: Modelled Increases in Traffic Flows (Weekday PM Peak) Phase 2/ Early Phase 3 End Phase 3 Land Use Hourly Weekday Peak Two-Way Traffic Flows % Increase Relative to Total Base Levels Flows Hourly WeekdayPeak Two-Way Traffic Flows % Increase Relative to Total Base Levels Flows Retail % 595* 6.% Residential % % Other 68.7% 68.7% Total % % Note: Percentage traffic flow increases are relative to 24/5 base levels. *It is assumed that underutilisation of town centre car parks on a weekday (particularly the Glades and Civic Centre car parks) will attract further parking at Phase 3. X:\Evidence_Base_2959_FINAL.doc 14

19 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 5.6 Impact of Policy of Restricting New Parking For residential development and other land uses, the trip rates deployed have been progressively refined during the AAP process reflecting the low car parking ratios. Those applied in the 28 assessment work provide representative of trip flows for the developments. However, those rates applied for the earlier modelling work were of a more approximate nature and produced flows that were somewhat higher and unduly robust. Trip values were discussed further in Section 4 of this report A policy of restricting new public parking space provision to serve the new retail developments will have a significant restraining influence on Saturday development flows. The extent of the potential reduction in flows is discussed later in this Section On Weekdays, the extent of underutilisation could have the tendency to increase flows associated with developments. However the transport strategy will be looking towards reducing the trip making from car parks during the peak hours by a number of means including: A VMS Strategy that promotes car use outside peak hours; A pricing strategy for public car parks that encourages shoppers to extend their duration of stay but avoids peak hour access and egress into car parks; A pricing strategy for public car parks that reduces the amount of long stay commuter car parking, and thereby further reduce peak hour access and egress into car parks; Travel planning promotion that encourages greater use of other modes during peak hours, reinforcing the perception that car use during the peak does not represent the most effective means of travel. The degree of housing to be provided in the town centre will lead to a greater degree of walking and cycling trips within the town centre for shopping trips taking into account the proximity of the retail offer Modelling undertaken to date has not fully taken into account the potential reduction in flows that can be achieved for the retail trips. The application of specific public parking policies can therefore be expected, alongside travel planning measures, to contribute to achieving the transport strategy ten in ten reductions Work undertaken by SBAX suggests that on a weekday, reduced trip making in the weekday peak is likely to be secured. This is considered will be the case if the AAP proposals provide adequate parking provision to provide for a viable town centre whilst not encouraging car use through over-provision of town centre parking. X:\Evidence_Base_2959_FINAL.doc 15

20 Bromley Town Centre Transport Strategy supporting AAP Evidence Base A comparison of the figures for Weekday derived by PBA, which assume a greater degree of take up of currently underutilised car parking, and those obtained from the SBAX work, which assume that the proposed parking provision is balanced and will not encourage greater car use, is given in Table 7. Table 7: Comparison of PBA and SBAX Modelled Increases in Traffic Flows (Weekday PM Peak End Phase 3) PBA SBAX Land Use Hourly Weekday Peak Two-Way Traffic Flows % Increase Relative to Total Base Levels Flows Hourly WeekdayPeak Two-Way Traffic Flows % Increase Relative to Total Base Levels Flows Retail % % Residential % % Other 68.7% 68.7% Total % % From Table 7 it can be seen that by adopting policies that do not seek to encourage a disproportionately higher use of underutilised car parking during the weekday, a reduction of around 2% in retail trips (6% down to 3.9%) can be expected More generally, and this would apply to both weekdays and Saturdays, the adoption of the policies listed above as promoted by the Transport Strategy would lead to reductions of traffic accessing or leaving the town centre car parks during peak hours. This could occur even if during the day was a greater take up of the underutilised car parking. On this basis it can be expected that by implementation of parking policies, further reductions in peak traffic of at least 2% can be expected to contribute to the Transport Strategy ten in ten approach. X:\Evidence_Base_2959_FINAL.doc 16

21 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 6 Ten in Ten: Travel Plan 6.1 Range of Potential Initiatives Soft measures are a range of initiatives that seek to give better information and opportunities, aimed at helping people to choose to reduce their car use while enhancing the attractiveness of alternatives. They include: o Workplace and school travel plans. o o o o Personalised travel planning, travel awareness campaigns, and public transport information and marketing. Car Clubs and car sharing schemes. Teleworking, teleconferencing and home shopping. Home Deliveries Recently a considerable amount of study work has been undertaken to determine the potential impact of these measures and these have been brought together in a report prepared for the Department for Transport Smarter Choices: Changing the Way We Travel. The report considers two scenarios high intensity and low intensity which relate to the likely expansion of activity and implementation of good practice over the next ten years. Projected changes in traffic levels are given for the two scenarios The high intensity scenario relates to the potential provided by a significant expansion of activity which is representative of a much more widespread implementation of present good practice. However this is considered to be to a realistic level and takes into account constraints of money and other resources, and suitability or effectiveness according to local circumstances. It should be noted that other Authorities are comprehensively taking forward this approach (e.g. Cambridgeshire and Northamptonshire County Councils) The low intensity scenario is broadly defined as a projection of 23/4 levels of local and national activity on soft measures Soft measures would support the transport objectives described previously. 6.2 Soft Measures and Traffic Reductions The results of the DfT study work is given in Table 8 below, which shows the journey change factors likely to apply for journeys by car to work, on business and for other purposes. These are given for the high and low intensity scenarios, and relate to urban areas. X:\Evidence_Base_2959_FINAL.doc 17

22 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Table 8: Journey Change Factors for Urban Areas Journey High Intensity Scenario Purpose Low Intensity Scenario Cars Work Workplace travel plans, car sharing and teleworking together cut car travel to work by 26%; personalised travel planning cuts it by 5%; public transport formation and marketing by 1.1%; travel awareness campaigns by 1%; car clubs by.6%. Total reduction of 33.16% Workplace travel plans, car sharing and teleworking together cut car travel to work by 8%; personalised travel planning cuts it by 1%; public transport information and marketing by.3%; travel awareness campaigns by.1%; car clubs by.3%. Total reduction of 9.43% Journey Change Factor Cars Business Teleconferencing cuts business travel by 18%; personalised travel planning cuts it by 5%; public transport information and marketing by 1.1%; travel awareness campaigns by 1%; car clubs by.6%. Total reduction of 25.16% Teleconferencing cuts business travel by 2.5%; personalised travel planning cuts it by 1%; public transport information and marketing by.3%; travel awareness campaigns by.1%; car clubs by.3%. Total reduction of 3.93% Journey Change Factor Cars Other Personalised travel planning cuts cars other travel by 5%; public transport information and marketing cuts it by 1.1%; travel awareness campaigns by 1%; car clubs by.6%; school travel plans cut the escort education portion of cars other by 2%; home delivery cuts the shopping portion of cars other by 4%; local collection points cut the personal business portion of cars other by 1.5%. Total reduction of 8.5% Personalised travel planning cuts cars other travel by 1%; public transport information and marketing cuts it by.3%; travel awareness campaigns by.1%; car clubs by.3%; school travel plans cut the escort education portion of cars other by 4%; home delivery cuts the shopping portion of cars other by 1%; local collection points cut the personal business portion of cars other by 1.5%. Total reduction of 1.86% Journey Change Factor Table 8 indicates for the high intensity scenario that there are considerable potential reductions for car trips related to journey to work and on business, and for other trip purpose a substantial reduction of 8% is projected. Even for the low intensity scenario, journeys to work could be reduced by 9%, although lower reductions of 4% and 2% are suggested for X:\Evidence_Base_2959_FINAL.doc 18

23 Bromley Town Centre Transport Strategy supporting AAP Evidence Base business and other categories These factors can then be applied to traffic flow data for the respective categories and an overall reduction figure obtained for future traffic levels. This has been done in the DfT study work by applying the factors to various traffic categories using data from the National Transport Model (NTM). The impacts of soft factors in future traffic flows for the urban traffic categories are given in Table 9 below. Table 9: Impacts of soft factors on weekday Bromley traffic levels Impact on Low intensity scenario High intensity scenario Impact on Urban traffic 3% 14% Urban traffic Peak-time urban traffic 5% 21% Peak-time urban traffic Off-peak urban traffic 3% 13% Off-peak urban traffic The impact of soft factors on future traffic levels can therefore be considerable. The actual reduction to be achieved could be influenced by both LB Bromley (through the planning system and the Area Action Plan) and other factors outside the Borough s control which would influence through movements. The figures suggest that for the weekday peak at least a 5% reduction could be expected and with a greater focus on soft measures within and outside the Borough there is the potential to reach 21% Applying the figures in Table 8 to the journey purpose data for Bromley given in Section 4 of the Transport Strategy, and assuming that proportions apply to both local and through traffic, the traffic reductions given in Table 1 would apply. Table 1: Impacts of soft factors on Weekday future traffic levels Journey Traffic Low intensity scenario Purpose Level High intensity scenario Change Factor (from Table A) Revised Traffic Level Change Factor (from Table A) Revised Traffic Level Shopping and related purposes Work and Education 6% or 6 units 38% or 38 units units units Business 2% or 2 units units X:\Evidence_Base_2959_FINAL.doc 19

24 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Total Traffic 1 units 82.2 units 95.3 units Reduction in Traffic 17.8 units or 18% 4.7 units or 5% Table 1 indicates that a range of between 5% and 18% would be appropriate for Bromley on a weekday, which is of a similar order to the Table 9 reductions The relationship of these figures in Table 9 with the Saturday flows is somewhat uncertain but the off-peak factors may have some application, although the impact of business and school related trips during the weekday and the predominance of retail trip making on the Saturday would inevitably influence the impact. Using the same approach as applied for a weekday results in the reductions given in Table 11 below. Table 11: Impacts of soft factors on Saturday future traffic levels Journey Traffic Low intensity scenario Purpose Level High intensity scenario Change Factor (from Table A) Revised Traffic Level Change Factor (from Table A) Revised Traffic Level Shopping and related purposes Work and Education 6% or 81 units 16% or 16 units units units Business 3% or 3 units units Total Traffic 1 units 87.5 units 96.9 units Reduction in Traffic 12.5 units or 12% 3.1 units or 3% Table 11 indicates that a range of between 3% and 12% would be appropriate for Bromley on a Saturday, which is of a similar order to the Table B reductions for off-peak urban traffic In order to maximise the benefits that can be obtained from progressing soft factors, a town centre wide approach should be taken forward involving existing and new businesses, retail companies and shop owners, residential developments, local services and other town centre located organisations. A town centre travel plan manager would review, publicise, coordinate X:\Evidence_Base_2959_FINAL.doc 2

25 Bromley Town Centre Transport Strategy supporting AAP Evidence Base and progress the full range soft measures. For new developments this would involve ensuring that there is compliance with conditions set out and agreed as part of planning approval process. For existing town centre companies it will be important that the manager effectively engages with all organisations based in the town centre and to build on the initial work in developing a travel plan with the Glades and Bank of America. This could take the form of an action group of key representatives to promote and otherwise encourage the adoption of best practice, although an action orientated approach would need to be fostered In summary the impact of soft measures on overall traffic levels in Bromley, could in weekday peak conditions, lead to a reduction of between 5% and 18%, while on the Saturday the reduction could lie between 3% and 12%. 6.3 Ten in Ten: Overall Impact The overall impact of Ten in Ten through the implementation of parking policy and travel plan measures is summarised in Table 12 below. Table 12: Summary of Ten in Ten Impacts Weekday Saturday % Reduction Parking Policy Measures Reduction of 2% Reduction of 2% Travel Plan Measures Reduction of between 5 18% Reduction of between 3 12% Overall Impact 7% to 2% reduction 5% to 14% reduction It can be seen that the overall impact of implementing Ten in Ten will be the reduction of traffic flows within the range of 7-2% in the weekday peak, and 5-14% in the Saturday peak These reductions are assuming that the mitigation measures implemented will only influence internal town centre trip making, and that through traffic will remain at the 27 level. However GLA targets as set out in the London Plan aim for a reduction in overall traffic growth in levels throughout sub regions (Table 13). It can be seen that for Outer London Town Centres (which Bromley is) a target reduction of -1% in traffic level growth is projected. It is envisaged that post 211 GLA policy, such as the application of soft measures e.g. travel plans and improvements to public transport, will continue to aim for lower traffic flows across London. As such there is the potential for further reduction in through traffic within X:\Evidence_Base_2959_FINAL.doc 21

26 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Bromley Town Centre over the AAP timeframe (28-223). This would contribute to greater reductions in traffic levels than those seen in Table 12. It can therefore be expected that the 1% reduction as envisaged in the Ten in Ten approach is both practicable and achievable. Table 13: Sub regional projected percentage changes in traffic growth, (Source: London Plan) Central London Inner London Outer London Outer London Town Centres Boroughs in the Central Sub-region Boroughs in the East Sub-region Boroughs in the West Sub-region Boroughs in the North Sub-region Boroughs in the South Sub-region London Average The next section of this report examines the effect of the revised AAP development trips on the highway network, and then goes on the discuss the impact of implementing Ten in Ten. X:\Evidence_Base_2959_FINAL.doc 22

27 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 7 Modal change and Development Trips Both the Hyder and SBAx modelling work has examined the traffic impact of the AAP development by simply adding the development trips to the 24/5 flows presented as the base in the Hyder Model. This approach has been continued to enable the town centre wide impacts to be assessed. The 24/5 Hyder Base Car Trips are presented in Appendix D By adding the reworked AAP development trips (as shown in Table 3) to the 24/5 base case from the Hyder Model it is possible to see how the development might affect traffic flows on the overall town centre highway network. It is also possible to see how adopting mitigation measures in the town centre, which aim to reduce the proportion of car use by 1% ( ten in ten ), will affect modal split. The key test here is that there should be no worse detriment in that the development traffic should not exceed 24/5 levels Tables 14 and 15 show the weekday PM peak and Saturday peak flows expected at the end of AAP Phase 3 and also after ten in ten has been adopted. Table 14 deals with applying the ten in ten for all car traffic in the town centre including through trips and internal trips, while Table 15 looks at ten in ten only for internal trip making in the town centre only. Table 14: Reduction to All Town Centre Car Trips, End of Phase 3 All Car Trips Weekday PM Peak Saturday Peak Hyder 24/5 Base Car Trips Base ALL modes % Car Mode Share 3% 48% AAP Phase 3 Development Car Trips Base plus Development ALL modes Base plus Development Car Trips Reduce base plus dev Flows by 1% (Ten in Ten) New % Car Mode Share with Ten in Ten 27% 43% Table 15: Reductions to Internal Town Centre Car Trips Only, End of Phase 3 Internal Town Centre Car Trips Only Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Base ALL modes % Car Mode share 3% 48% 24/5 Base Car Town Centre Trips /5 Base Car Through Trips AAP Phase 3 Development Car Trips Base plus Development ALL modes All base plus Development Car Trips Town Centre base plus Development Car X:\Evidence_Base_2959_FINAL.doc 23

28 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Trips Reduce Town Centre base plus dev trips by 1% (Ten in Ten) Reduced Town Centre trips plus through trips New % Car Mode Share with Ten in Ten 29% 46% Figure 3 Weekday PM Peak Mode Shares Weekday PM Peak: 24/5 Mode Share Weekday PM Peak: Mode Share With Development After Ten i n Ten 3% 27% 7% Total Peak Traffic Flow: 3313 Car All Other Modes Total Peak Traffic Flow: % Car All Other Modes Figure 4: Saturday Peak Mode Shares Saturday Peak: 24/5 Mode Share Saturday Peak: Mode Share With Development After Implementation of Ten in Ten 52% 48% 57% 43% Total Peak Traffic Flow: Total Peak Traffic Flow: Car All other Modes Car All Other Modes X:\Evidence_Base_2959_FINAL.doc 24

29 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Table 14 shows that when adding the Phase 3 development traffic to the base traffic flows, traffic on the highway network is increased by 855 trips. Adopting a 1% reduction in all town centre car trips brings this traffic level back down to below base (24/5) levels. This reduces the current modal car share on a weekday (3%) by 3% to 27%, and the current modal car share on a Saturday (48%) by 5% to 43%. Figures 3 and 4 show the modal split changes. The overall trip making reduces below the 24/5 levels Table 15 applies the same methodology but reduces only internal town centre trips (i.e. trips that have an origin and/or destination in the town centre) by 1% rather than all traffic on the highway network. Reducing only the internal trips reflects the scenario that only the people visiting the town centre are influenced by mitigation measures, rather than through traffic as well. It can be seen that on this basis with mitigation measures in place traffic levels remain higher than the base 24/5 level. Traffic increases by 4.1% in the PM peak and 2.8% in the Saturday peak compared to 24/5 levels. Reductions seen with car modal share are also less, with the current car modal share on a weekday of 3% reducing to 29% and car share on a Saturday reducing from 48% to 46%. It may be the case that actual trip making will lie between the Table 4 and Table 5 levels with traffic after the adoption of ten in ten being at a similar level to 24/ However between 24 and 27 overall traffic levels within the town centre have fallen from a 12 hourly flow of 135,54 in 24 to 123,51 in 27 (a fall of 9%), therefore adopting a base of 24/5 is not strictly representative of current traffic levels. As such 24/5 base traffic levels have been factored down to 27 levels to take account of the lower traffic flows on the highway network. Tables 16 and17 summarise the results. Table 16: All vehicle Traffic, factored back to 27 All Vehicle Traffic Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Factored down to Additional Development Car Trips plus Development Car Trips Reduce 28 plus dev Flows by 1% X:\Evidence_Base_2959_FINAL.doc 25

30 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Table 17: Internal Trips, factored back to 27 Internal Town Centre Vehicle Traffic Only (no through traffic) Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Factored down to /5 Base Car Town Centre Trips /5 Base Car Through Trips TC Factor down to Thru Factor down to Additional Development Car Trips TC 28 plus Development Car Trips TC plus Development plus thru 28 Car Trips Reduce TC 28 plus dev by 1% Reduced TC plus dev plus thru It can be seen from Table 16 that, taking into account all traffic on the highway network and mitigation measures in place ( ten in ten ), there is an overall reduction in flows from 24/5 in both the weekday PM peak (8783 compared to 994) and the Saturday peak of (8556 compared to 9524). This is around a 5% reduction from 24/5 traffic levels in the town centre Table 17 applies the same methodology but reduces only internal town centre trips by 1% rather than all traffic on the highway network. It can be seen that with mitigation measures in place traffic levels also fall below the 24/5 level. This is in contrast to Table 15 where traffic increases were seen. This difference is seen because development traffic is being added onto the lowered 27 traffic level, rather than the higher 24/5 base. This is a more appropriate comparison given that the 27 level is more representative of the current traffic levels within the town centre In summary the above calculations would suggest that at a strategic town centre wide level a target of 1% would help lead to traffic levels with the AAP developments being equivalent to 24/5 traffic levels. Taking into account the reduction in town centre traffic that has occurred since 24/5, by application of the ten in ten approach, traffic will fall below the 24/5 level. X:\Evidence_Base_2959_FINAL.doc 26

31 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 8 AAP Targets Five specific targets have been identified for the Transport Strategy: Target One: Reduce the proportion of car use by 1% over ten years ( ten in ten ) i.e. by the end of AAP Phase 2 Target Two: To manage the level of traffic, so that the following traffic targets are not exceeded (compared to 21 levels): o o o -1% up to 211 (which is the Mayor of London s Transport Strategy target) % up to the end of AAP Phase Two +3% up to the end of AAP Phase Three Target Three: Delivery and Servicing Plan and Codes of Construction Practice to be approved for all new major developments prior to implementation Target Four: A Parking Plan for implementation to be approved within 3 years Target Five: A Town Centre wide Travel Plan to be implemented within 3 years and associated plans for new developments to be in place upon occupation Targets One and Two relate specifically to traffic levels within the town centre Target One relates to reducing the proportion of car use by 1% by the end of Phase Two. Tables in the previous section show that adopting ten in ten will have a considerable impact on reducing traffic flows within the town centre. The mitigation measures that will be implemented to ensure this target is met are described in Sections 5 and 6 (parking controls and travel plans measures respectively) Target Two requires comparing traffic levels in the town centre to 21 levels. In order to calculate the change in traffic from 21 for each phase of the AAP it is necessary to factor back the Hyder 24/5 base trips to 21 levels. This factoring is based on profiles obtained from existing traffic counts undertaken at eight sites around the town centre. Table 18 shows the 12 hourly and peak hour traffic counts that were used to obtain the profile back to 21. It can be seen that traffic levels were approximately 11-15% higher in 21 than in 27. X:\Evidence_Base_2959_FINAL.doc 27

32 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Table 18: Traffic Cordon Counts for Bromley Town Centre % Change from Hourly Peaks For the purposes of this exercise the 12 hourly profile has been used for the Saturday peak and the average peak profile has been used for the weekday peak Tables 19 and 2 show the overall percentage change from 21 when adding the Phase 2 development trips onto 27 flows. Table19: Change from 21 End of Phase 2 Internal and Through Trips Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Factored up to Factored down to Additional Development Car Trips plus Development Car Trips Oveall % change from Reduce 28 plus dev Flows by 1% Overall% change from Table 2: Change from 2, End of Phase 2 (Internal Trips Only) Internal Trips Only Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Factored up to /5 Base Car Town Centre Trips /5 Base Car Through Trips TC Factored down to Thru Factored down to Additional Development Car Trips TC 28 plus Development Car Trips TC plus Development plus thru 28 Car Trips Overall%change from Reduce TC 28 plus dev by 1% Reduced TC plus dev plus thru Overall%change from X:\Evidence_Base_2959_FINAL.doc 28

33 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Tables 19 and 2 show the percentage change from 21 seen at the end of Phase 2, when only a proportion of the total development has been delivered. It can been seen that, without ten in ten, traffic levels at the end of Phase Two are 9.5% lower than 21 for the weekday peak and 5% lower than 21 for the Saturday peak. The reason that they remain lower than the 21 level is because, as previously mentioned, traffic levels between 21 and 27 have fallen considerably Adopting ten in ten reduces these flows further to between 9.9% to 18.6%, depending on whether ten in ten is taken to include both internal and through trips in the town centre or just internal trip making The AAP target of a % increase in traffic flows up to the end of Phase 2 compared to 21 levels is therefore achieved Tables 21 and 22 show the addition of Phase 3 trips to the highway network. Table 21: Changes from 21, End of Phase 3 Internal and Through Trips Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Factored up to Factored down to Additional Development Car Trips plus Development Car Trips Oveall % change from Reduce 28 plus dev Flows by 1% Overall % change from Table 22: Changes from 21, End of Phase 2 (Internal Trips Only) Internal Trips Only Weekday PM Saturday Peak Hyder 24/5 Base Car Trips Factored up to /5 Base Car Town Centre Trips /5 Base Car Through Trips TC Factored down to Thru Factored down to Additional Development Car Trips TC 28 plus Development Car Trips TC plus Development plus thru 28 Car Trips Overall%change from Reduce TC 28 plus dev by 1% Reduced TC plus dev plus thru Overall%change from X:\Evidence_Base_2959_FINAL.doc 29

34 Bromley Town Centre Transport Strategy supporting AAP Evidence Base At the end of Phase Three, with all the development traffic now added to the highway network, it can be seen that traffic levels have risen from Phase two, although still remain significantly below the 21 level. At no point do traffic levels with AAP development included reach 21 levels. With the mitigation measures the trips on the highway network are further reduced In summary the AAP development trips that are added to the highway network both in Phase 2 and Phase 3 do not exceed 21 traffic levels, as shown in Figure 5 (the Ten in Ten reductions have been applied to internal trip making), and the AAP Target Two (traffic targets) should be comfortably met. Figure 5: Changes in weekday PM peak and Saturday peak traffic throughout the Phases of the AAP End of Phase 1 End of Phase 2 End of Phase 3-2 Weekday Pm Weekday PM adopting Ten in Ten Saturday Peak Saturday Peak adopting Ten in Ten X:\Evidence_Base_2959_FINAL.doc 3

35 Bromley Town Centre Transport Strategy supporting AAP Evidence Base 9 Conclusions This evidence base describes the two stages of modelling work that have been undertaken, supplemented by further strategic study work undertaken by PBA. Taken together the modelling and strategic study work has informed the preparation of the Transport Strategy which underpins the proposals in the AAP The modelling work has shown that the medium term developments (Phase2/ early Phase3) can be accommodated by making highway and traffic management improvements to the network serving the town centre. The modelling has taken on board the proposals within the AAP to reduce the size of certain car parks thereby balancing the addition of new parking provision (particularly on Site G). However, given the current degree of underutilisation of existing town centre car parks, particularly during weekdays, it will be important for car parking to be managed to avoid retail car trips having an adverse impact on peak hour traffic The strategic study work which supplements the modelling within the AAP has considered the impact of policies of restricting new parking provision supported by a range of measures including a VMS strategy, car park pricing strategies, travel planning and new housing within the town centre to obviate the need to drive to access the retail offer. These measures are included within the Transport Strategy In addition to the effective management of existing assets (particularly parking provision), the Transport Strategy underlines the importance of capacity building for taking forward Phase 2 into early Phase 3. This is supported by the modelling in terms of the highway and traffic management mitigation measures that will be required to provide reasonable provision for access by car. But the capacity building is also required for other modes walking, cycling and for accessing public transport in order to facilitate the degree of mode change needed to ensure that the highway network performance is not compromised Beyond early Phase 3, the strategic study work has demonstrated that it will be possible to accommodate the full development quantum proposed within the AAP up to the end of Phase 3. This will be achieved by the rigorous implementation of the range of strategies identified in the Transport Strategy for the town centre This evidence base underlines the importance of taking forward a range of strategies that will reduce the growth of traffic that could be associated with scale of new development proposed within the AAP for the town centre. With the adoption of soft measures such as workplace and school travel plans, travel awareness campaigns and information, car clubs and car sharing, home deliveries etc., there is the potential to significantly reduce traffic levels in the town centre. Taken together with the adoption of a comprehensive parking strategy and the degree of capacity building proposed by the Transport Strategy for modes other than the car, the evidence base shows that the overall impact would be between a 7% to 2% reduction for a weekday peak and 5% to 14% on Saturday peak. This supports the 1% reduction as envisaged in the Ten in Ten approach as identified as Target One in the Transport Strategy. X:\Evidence_Base_2959_FINAL.doc 31

36 Bromley Town Centre Transport Strategy supporting AAP Evidence Base The strategic review work within the evidence base shows that with the Ten in Ten approach, it is likely to be the case that traffic levels within the town centre after all the AAP developments are in place are likely to remain roughly at similar levels to those in 24/ However the strategic review also considers the circumstance that subsequent to 24 there has been a further fall of 9% in town centre traffic levels. Adopting a base of 24/5 (as used in the modelling) is therefore not strictly representative of current traffic levels. Taking into account this further reduction, it will be the case that even with the AAP developments, traffic will fall below the 24/ 5 levels The strategic review also considered the AAP Target 2 which concerned managing the levels of traffic relative to 21 levels (this year being incorporated within the Mayor of London s Transport Strategy). The Phase 2 and Phase 3 development trips when added to the highway network trips do not exceed 21 levels showing that the AAP Target Two (traffic targets) should be comfortably met The evidence base encompassing modelling and a strategic review demonstrates that with the implementation of the mitigation measures put forward in the comprehensive Transport Strategy that the developments proposed within the AAP can be satisfactorily accommodated within Bromley Town Centre. X:\Evidence_Base_2959_FINAL.doc 32

37 Bromley Town Centre Transport Strategy supporting AAP Evidence Base Appendix A X:\Evidence_Base_2959_FINAL.doc 33

38 London Borough of Bromley Bromley Town Centre Micro - Simulation Modelling Assessment of Impact of Potential Developments Final Report July 27 Report no: LN933/ D3.1

39 London Borough of Bromley Bromley Town Centre Micro - Simulation Modelling Assessment of Impact of Potential Developments Final Report Author: T Thivaharan Checker: O Konyeha Approver: R Morris Report no: LN933/ D3.1 Date: July 27 This report has been prepared for London Borough of Bromley in accordance with the terms and conditions of appointment for Assessment of Impact of Potential Developments. Hyder Consulting (UK) Ltd ( ) cannot accept any responsibility for any use of or reliance on the contents of this report by any third party. Hyder Consulting (UK) Limited Bressenden Place, London SW1E 5DZ, UK Tel: +44 ()87 36 Fax: +44 ()

40 Contents E Executive Summary Introduction Objectives Scope and Methodology Development Options Methodology Phase 1 Development Assessment Weekday PM Additional Development Trips Weekday PM Headline Statistics Weekday PM Detailed Impacts Saturday Additional Development Trips Saturday Headline Statistics Saturday Detailed Impacts Phase 2 Development Assessment Weekday PM Additional Development Trips Weekday PM Headline Statistics Weekday PM Detailed Impacts Saturday Additional Development Trips Saturday Headline Statistics Saturday Detailed Impacts Mitigation Measures Phase 3 Development Assessment Weekday PM Additional Development Trips Weekday PM Headline Statistics Weekday PM Detailed Impacts Saturday Additional Development Trips Saturday Headline Statistics Saturday Detailed Impacts Additional Mitigation Measures Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page i Hyder Consulting (UK) Ltd

41 7 Conclusions...43 APPENDIX Phase 1..A Phase 2.. B Phase 3.. C Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page ii Hyder Consulting (UK) Ltd

42 E Executive Summary Hyder consulting (UK) Ltd. was commissioned in January 26 to undertake assessment of the impact of potential development opportunities within the Bromley Town Centre. A Paramics microsimulation traffic model was developed to undertake the assessment of six scenarios: Base (existing) Development Phase 1 Development Phase 2 without mitigation Development Phase 2 with mitigation Development Phase 3 without mitigation Development Phase 3 with mitigation Each scenario was tested for weekday PM peak traffic conditions (16 to 19 hours), and Saturday afternoon (1 to 16 hours), taking the total number of test models to twelve. The test models assessed development phases 2 and 3 with and without mitigation measures intended to minimise the impact of the proposals. The tests concluded that Phase 1 could be accommodated on the local road network in both the weekday and Saturday models with no mitigation measures other than traffic signal optimisation. Phase 2 could be accommodated on the local road network in the weekday PM scenario provided a package of physical mitigation measures were implemented to reduce the impact. If implemented these measures would mitigate the development proposals and provide an ongoing positive net benefit to the area in that scenario. The Phase 2 Saturday scenario, with the above mentioned mitigation measures, results in an 11% increase in overall network delay. This may be acceptable provided the positive weekday benefit was deemed sufficient to offset the Saturday impact, which equates to around 1-seconds per vehicle. Such economic appraisal is beyond the scope of this study. Phase 3 could not be comfortably accommodated, even with an extended package of mitigation measures, under Saturday traffic conditions. The impact of Phase 3 on the weekday scenario was negligible, but whereas the Phase 2 scenario resulted in a positive benefit that could be used to offset the Saturday delay, the Phase 3 did not. In conclusion development proposals under Phase 1 could progress immediately. Phase 2 could progress in conjunction with the recommended mitigations measures, provided the Saturday impact was not deemed unacceptable by LB Bromley. Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 1 Hyder Consulting (UK) Ltd

43 Further study would be required in order to revise the Phase 3 development proposals in order to accommodate the predicted traffic on the road network, possibly requiring the testing of a more extensive package of mitigation measures. Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 2 Hyder Consulting (UK) Ltd

44 1 Introduction Hyder consulting (UK) Ltd. was commissioned in January 26 to undertake an assessment of the impact of potential development opportunities within the Bromley Town Centre on level of congestion at key junctions. This assessment, is to support the Bromley Area Action Plan (AAP), and utilises previously developed PARAMICS micro-simulation models for the town centre. Figure 1.1 shows the extent of the modelled network and the location of the proposed developments. This document provides outline of the objectives, assumptions, adopted methodology, and the assessment results and main conclusions. Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 3 Hyder Consulting (UK) Ltd

45 Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 4 Hyder Consulting (UK) Ltd

46 2 Objectives To assess the impact of potential development opportunities on the Bromley Town centre traffic network operation. To determine how successfully a range of mitigation measures will be in relieving the additional congestion expected by the extra demand generated by the proposed developments., with regard to both buses and general traffic. Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 5 Hyder Consulting (UK) Ltd

47 3 Scope and Methodology 3.1 Development Options LB Bromley has set out three time phases for the completion of the developments these are: Phase 1: developments implemented within the first 5 years Phase 2: developments implemented within the first 1 years Phase 3: developments implemented within the first 15 years (All) The attached Table 3.1, supplied by Peter Brett Associates (PBA), shows the managed development schedule by phase. 3.2 Methodology Trip generation Trip generation data for the weekday PM peak and Saturday periods, also provided by PBA, has been used in this assessment. These periods were selected as they were considered to be the most appropriate to the major trip generators which mainly concern retail development. Account has also been taken of the demand profile of existing traffic on the network. Demand matrices were then prepared by Hyder for the two time periods for each of the three development phases mentioned in 3.1, which amount to six development demand cases. The networks were modified to test the Phase 2 and 3 demand cases in with mitigation and no mitigation scenarios, which, including the two Base models and Phase 1, bringing the total number of modelled scenarios to twelve. Trip Distribution In general, the existing Origin / Destination (O/D) trip proportions were used to distribute the new developments trips to other zones. The only exception is when retail based trips to a particular development zone are displaced to a car park in another zone due to limits on parking, caused by the reduction in the size of car parks or the unavailability of sufficient parking. For example, a reduction in the size of The Hill car park is to be modelled, coupled with the provision of food retail on the site. The excess parking demand is assumed to be displaced to other car parks in the town centre such as Bromley North. Typical displacement patterns are shown on Figure 3.2 alongside existing and proposed changes to the town centre parking provision. When parking is displaced the O/D trip proportions, for the particular development zone from which the displacement has taken place, is deployed for determining trips from the new parking location. Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 6 Hyder Consulting (UK) Ltd

48 Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 7 Hyder Consulting (UK) Ltd

49 Assessment of Impact of Potential Developments Bromley Town Centre Micro - Simulation Modelling Page 8 Hyder Consulting (UK) Ltd