Active Traffic Management (ATM) Feasibility Study

Transcription

1 Active Traffic Management (ATM) Feasibility Study Submitted to: Washington State Department of Transportation Urban Corridors Office 401 Second Avenue S., Suite 560 Seattle, WA Submitted by: PB Americas, Inc. Carter + Burgess EarthTech, Inc. Telvent Farradyne

2 Active Traffic Management (ATM) Feasibility Study Table of Contents Executive Summary Introduction The Puget Sound Experience Active Traffic Management Techniques Study Process and Methodology Phase Phase Speed Harmonization Design Concepts Capital, Operations and Maintenance Costs Benefits Assessment Operations Assessment Operations Operator Workload Compatibility with High Occupancy Toll or Managed Lanes Maintenance Compliance and Enforcement Signing Overhead Sign Bridge Spacing Queue Warning Design Concepts Capital, Operations and Maintenance Costs Benefits Assessment Operations Assessment Operations Operator Workload Compatibility with High Occupancy Toll or Managed Lanes Maintenance Compliance and Enforcement Signing Junction Control Design Concepts Capital, Operations and Maintenance Costs Benefits Assessment Operations Assessment Operations Operator Workload Compatibility with High Occupancy Toll or Managed Lanes Maintenance Compliance and Enforcement Signing i

3 8.0 Hard Shoulder Running Design Concept Capital, Operations and Maintenance Costs Benefits Assessment Operations Assessment Operations Operator Workload Compatibility with High Occupancy Toll or Managed Lanes Maintenance Compliance and Enforcement Safety Signing Design Elements Other Considerations Dynamic Re-Routing Design Concept Capital, Operations and Maintenance Costs Benefits Assessment Operations Assessment Operations Traveler Information Design Concepts and Costs Capital, Operations and Maintenance Costs Benefits Assessment Operations Assessment Operations Integration with Current ITS Infrastructure Institutional Issues Recommendations Recommendations for the I-405 Study Area Recommendations for the Freeway System Beyond the Study Area Recommendations to Address Institutional and Organizational Issues Appendices ii

4 List of Figures Figure 1 - Lost Throughput on Puget Sound Freeways... 7 Figure 2 - Lost Throughput on I-405 in Renton... 8 Figure 3 - Causes of Congestion in the United States... 8 Figure 4 - Speed-Flow Curve for I Figure 5 - Rear-end Collisions, Congestion and Hours of Delay (Northbound I-5) Figure 6 - Phase 1 Corridors for Consideration Figure 7 - Speed Harmonization: Speed, Lane Control & Icons Figure 8 Speed Harmonization: Speed, Lane Control and VMS Figure 9 Speed Harmonization: Post-mounted Variable Speed Limit Signs Figure 10 Queue Warning VMS Sign Figure 11 Queue Warning Static Sign with Flasher Figure 12 Junction Control Upstream Entry Point (Active & Inactive) Figure 13 Junction Control Advance of Exit Ramp (Active & Inactive) Figure 14 Junction Control Beyond Exit Ramp (Active) Figure 15 Hard Shoulder Running: Lane Use Mast Arm (Active & Inactive) Figure 16 Hard Shoulder Running ¾ Mile Advance (Active & Inactive) Figure 17 Hard Shoulder Running: Upstream Entrance CMS (Active & Inactive) Figure 18 - Junction Control at an Exit with Hard Shoulder Running Figure 19 Dynamic Rerouting: Hybrid DMS Supplemental Destination Signing Normal Condition Figure 20 Dynamic Rerouting: Hybrid DMS Supplemental Destination Signing Congested Condition Figure 21 Traveler Information: Hybrid DMS Travel Time Sign Normal Condition Figure 22 Traveler Information: Hybrid DMS Travel Time Sign Congested Condition Figure 23 Traveler Information: Double Condition VMS List of Tables Table 1 - ATM Technique Cost Summary... 2 Table 2 - ATM Technique Implementation Potential iii

5 List of Abbreviations and Acronyms ATM Active Traffic Management CCTV DMS FHWA FTE GP HOT HOV IRT ITS LCD LED MUTCD NTCIP NWR O&M PM PS&E PSRC SOP SOV TMC TMS TMC UPS US VMS VSL WSDOT WSP Closed Circuit Television Dynamic Message Sign Federal Highway Administration Full-Time Employee General Purpose High Occupancy Toll High Occupancy Vehicle Incident Response Team Intelligent Transportation System Lane Control Display Light Emitting Diode Manual on Uniform Traffic Control Devices National Transportation Communications for ITS Protocol Northwest Region Operations and Maintenance Preventive Maintenance Plans, Specifications and Estimate Puget Sound Regional Council Standard Operating Procedure Single-Occupant Vehicle Traffic Management Center Transportation Management System Traffic Management Center Uninterruptible Power Supply United States Variable Message Sign Variable Speed Limit Washington State Department of Transportation Washington State Patrol iv

6 Executive Summary It is estimated that 1.7 million new people will locate in the central Puget Sound region over the next 30 years and 1.1 million new jobs will be created. This growth has been projected to translate into 1.5 million new vehicles, but our freeway system is already significantly congested for many hours of the day. In addition, the Puget Sound region has a limited number of freeway facilities only two major north-south and two east-west interstates/state routes and the opportunities to expand these facilities are limited. To help address this increasing congestion, the Washington State Department of Transportation (WSDOT) has drawn upon the European experience (Denmark, England, Germany and the Netherlands) for innovative techniques to manage the region s roadway capacity. Coupled with their experience as a national leader in managing freeway facilities through ramp metering, HOV lanes and incident management, WSDOT hopes to use active traffic management (ATM) strategies to improve traffic flow and safety using integrated systems and coordinated responses. ATM is a tool that can maximize safety and traffic flow by dynamically managing and controlling traffic based on the prevailing traffic conditions. These strategies include speed harmonization, queue warning, junction control, hard shoulder running, dynamic re-routing, and traveler information. Speed harmonization involves reducing speed limits in areas of congestion to maintain better traffic flow and reduce the risk of collisions. Queue warning warns motorists of downstream queues and directs traffic to alternate lanes, thereby reducing the likelihood of speed differentials and collisions due to queuing. Junction control directs traffic to specific lanes based on the traffic demand (e.g. utilizes mainline capacity by giving priority to higher ramp volumes). Hard shoulder running utilizes the shoulder as a travel lane to allow traffic to move around an incident, which helps to minimize recurrent congestion and manage traffic during incidents. Dynamic rerouting involves changing the destination signing to account for current traffic conditions in order to redirect traffic to less congested facilities. Traveler information or providing travel times is already being provided by WSDOT in the Puget Sound region and allows motorists to make more informed pre-trip and en-route decisions. This feasibility study was conducted in two phases: a qualitative screening and a phase that incorporated both qualitative and quantitative assessments and analysis. The first phase qualitatively evaluated three major transportation corridors in the Puget Sound region to determine which corridor presented the best opportunity to test ATM techniques. The evaluation process used screening criteria such as data availability, infrastructure, traffic conditions, implementation potential, implementation feasibility, near- and long-term construction activities to evaluate the corridors. The southern section of I-405 (Tukwila to Factoria) was selected as the corridor most suited for further quantitative analysis, although I-5 was very close as the next highest rated corridor. There was not a wide variation in the corridor rankings which indicates that all corridors would be suitable for implementing ATM strategies. The second phase qualitatively and quantitatively assessed the six ATM techniques for application within the selected corridor. In addition, this phase explored the operational, policy and institutional issues for implementation as well as developed conceptual cost estimates (capital, operations and maintenance) and conducted microsimulation modeling to assess the benefits. Active Traffic Management Feasibility Study 1

7 A range of design concepts were developed for each of the ATM techniques, based on both European and US models. Capital and operations and maintenance costs are summarized in Table 1 for the various conceptual designs developed for the ATM techniques. Table 1 - ATM Technique Cost Summary ATM Technique Capital Cost Annual O&M Cost Estimated Benefit Speed $56 million $464,000 $13.6 million per year Harmonization (12 miles) Queue Warning $1.5 million per location Recommended to implement as part of speed harmonization, which would be inclusive of operations and maintenance costs for $0.78 million per year Junction Control $1.6 to $1.8 million per location Hard Shoulder Running Dynamic Rerouting Traveler Information $2.7 million per mile $1.7 million per mile $0.7 million to $1.2 million per location queue warning Varies based on location and implementation with other ATM techniques Varies based on location and implementation with other ATM techniques Up to $0.25 million per year N/A please see Section 8.3 Removed from consideration N/A please see Section 9.3 $43,000 (for four location) N/A please see Section 10.3 For speed harmonization, there is a potential cost savings of $13.6 million per year due to the reduction in collisions and reduced delay. This benefit translates into a system recovery cost in just over four years. The benefits of queue warning reveal that the system costs could be recovered in a little over three years. It was more difficult to fully assess the benefits of junction control (see Appendix C for more details). Using the SR 518 installation, it would take between six and eleven years to recover the system costs. Operational and policy issues were explored for each of the ATM techniques. They included an operations assessment which focused on topics such as operator workload, compatibility with HOT or managed lanes, maintenance, compliance and enforcement, safety, design elements, signing, and sign bridge spacing. Each technique provided unique considerations, for example operator workload for junction control at SeaTac Airport, which has mid-day and late evening peaks, would require TMC staffing and monitoring of the control systems outside of the current hours of operation. Therefore, there would be incremental workload increases if junction control were to be implemented independently in a number of locations. Another example pertains to compliance for hard shoulder running. Strict enforcement is paramount to safe operations and to maximize operational compliance. In addition, discussions, agreements, and standard operating procedures (SOPs) would be needed to ensure an orderly and safe operation of this ATM technique. Active Traffic Management Feasibility Study 2

8 Institutional issues were identified as well and were related to the areas of regulatory and legal issues, finance, organization and management issues, and human and facilities resources. For example, ATM must be a priority in programming and funding. Without it, techniques will be installed piecemeal and the benefits will not live up to the promise of the technology. Another issue was weekly staffing for TMC operations. In order to effectively manage the ATM techniques, the TMC will need to be staffed with operators 24 hours a day, seven days a week. The application of ATM techniques in the Puget Sound is consistent with WSDOT s traffic management philosophy and would provide them with another set of tools to manage traffic conditions. Much of the hardware required for speed harmonization fits well with the existing ITS infrastructure. In fact, the existing detector stations may be able to be used to provide the data needed for the speed harmonization system. The VMS used to support the various techniques are similar to the signs used throughout the region by WSDOT. Integration will take some effort, but WSDOT can continue to maintain its own ITS central software, as the source code is owned and new versions of the software can be built. A number of recommendations were developed by the study team for the I-405 study area, the freeway system outside of the study area, and to address the various institutional and organizational issues that were identified. They are summarized as follows: I-405 Study Area Implement speed harmonization throughout the study area, in both directions. Incorporate queue warning in the southbound direction at the SR 167 interchange. Study junction control in more depth on eastbound SR 518 in the vicinity of the North Airport Access Road and at the SR 167/I-405 interchange. Further investigate hard shoulder running by extending the limits on southbound SR 167. Drop dynamic re-routing from further consideration in favor of implementing travel time information signing. Implement specialty travel time signs at four locations. Use ATM techniques during construction for the maintenance of traffic. Combine ATM implementation with existing projects in the corridor for a potential two percent cost savings in the total project cost. Outside the I-405 Study Area Further investigate the ATM techniques that were identified as having potential benefits at locations outside of the study area. Focus region-wide implementation of travel time signing at locations that do not currently have VMS. Institutional and Organizational Issues Commitment to 24/7 operations. Commitment to required maintenance and replacement of ATM systems. Providing outreach to the public and stakeholder organizations to provide information on and education about the ATM techniques will be key to building trust. Outreach to elected and appointed officials and other decision-makers is critical. Coordination with local partners, particularly enforcement, will be needed. Active Traffic Management Feasibility Study 3

9 When speed harmonization is first implemented, provide information to the public and stakeholders as to why there are three different approaches to variable speed limits in Washington. Need improved analysis tools so benefits can be estimated more accurately. Get experimental use approval for several signing and/or control techniques that are not currently in compliance with the MUTCD. WSDOT should continue to participate in the national dialog on ATM techniques for the mutual benefit of all agencies involved. Active Traffic Management Feasibility Study 4

10 1.0 Introduction Congestion is a persistent problem for the Puget Sound region s freeway system, and our region is projected to continue growing in terms of total population and employment. It is estimated that 1.7 million new people will locate in the central Puget Sound region over the next 30 years and 1.1 million new jobs will be created. This growth has been projected to translate into 1.5 million new vehicles. Lined up at 15 feet each, 1.5 million vehicles would stretch for nearly 4,260 miles the distance from Seattle to New York City and then to Miami. When parked, bumper-to-bumper, the same 1.5 million additional vehicles would require a roadway 142 lanes wide and 30 miles long, the same length as I-405. The Puget Sound region has a limited number of freeway facilities only two major north-south and two east-west interstates/state routes and the opportunities to expand these facilities are limited. For this reason, the Washington State Department of Transportation (WSDOT) has elected to look to the European experience (Denmark, England, Germany and the Netherlands) for innovative and forward thinking techniques to manage the region s roadway capacity. The European experience includes active traffic management (ATM) strategies that improve traffic flow and safety using integrated systems and coordinated responses. In June 2006, a group of eleven transportation professionals, representing planning, design, and operations visited five European countries to study how these nations were addressing freeway congestion using ATM techniques. The trip was sponsored by the International Technology Scanning Program, a partnership of AASHTO, FHWA and the National Cooperative Highway Research Program of TRB. The trip purpose was to examine European congestion management programs, polices and experiences. International Technology Scanning Tour Key Findings: ATM is a tool to maximize both flow and safety. Active management strategies can help optimize the existing infrastructure during recurrent/ non-recurrent congestion. ATM may be used as an interim strategy to maximize the efficiency of corridors that may receive major capital investments. Operations must be a priority in planning, programming, and funding processes. Focus on trip reliability and customer orientation. Active traffic management can be defined as dynamically managing and controlling traffic based on prevailing conditions for recurrent and non-recurrent congestion. With travel demand on the rise and increasing congestion, coupled with the reality of today s financial constraints, congestion management can be a primary operational strategy for transportation agencies. ATM is a tool that can maximize safety and throughput and may be used as an interim strategy to maximize the efficiency of corridors that may ultimately receive major capital investments. The WSDOT is already a national leader in managing freeway facilities efficiently using ramp metering, HOV lanes, providing traveler information, and managing incidents. By taking advantage of the knowledgeable and dedicated operations staff who work with WSDOT s high- Active Traffic Management Feasibility Study 5

11 functioning traffic management system, these innovative ATM techniques would serve as additional tools to manage and utilize the region s freeway capacity effectively, efficiently, and safely. This report will discuss findings on ATM from the European experience, the study purpose and methodology, the ATM techniques assessed, costs and benefits at a conceptual level, and operational and policy issues associated with implementing these ATM strategies in the Puget Sound region. It will also identify recommended ATM techniques for implementation within the identified study area, as well as other locations within the region. Active Traffic Management Feasibility Study 6

12 2.0 The Puget Sound Experience The Central Puget Sound area experienced 520,000 person hours (370,000 vehicle hours) of daily delay in Congestion on our roadway facilities not only contributes to daily delay hours, it also means that our system is functioning with significant capacity reductions (Figure 1). In some cases, as on I-405 in Renton and downtown Bellevue, half of the capacity is lost due to recurrent and non-recurrent congestion during the peak travel period meaning our freeway system provides the least performance when it is needed the most. Figure 1 - Lost Throughput on Puget Sound Freeways As shown in Figure 2, the morning peak on I-405 in Renton operates at approximately 50 to 60 percent of its capacity, and operates at approximately 65 percent of its capacity from about 2 PM to 8 PM on the weekdays. Active Traffic Management Feasibility Study 7

13 Figure 2 - Lost Throughput on I-405 in Renton Figure 3 illustrates the typical sources of congestion in two categories: non-recurrent and recurrent. Non-recurrent congestion, which comprises 55 percent of all congestion, is the result of traffic incidents, inclement weather, construction work zones and special events. The other 45 percent is from recurrent congestion which is mostly attributed to bottlenecks and some lack of signal optimization. Figure 3 - Causes of Congestion in the United States The situation in the Puget Sound region is no different than that found for the US as a whole. Recognizing that constructing additional freeway lanes is costly and is not a sustainable strategy, managing the Puget Sound s current roadway capacity takes on a greater significance. Effectively managing roadway capacity can take two forms, one is to manage recurrent Active Traffic Management Feasibility Study 8

14 congestion and the other is to affect and then manage the non-recurrent sources of congestion, such as collisions. Maximizing the efficiency of the existing system to move people and goods is more reliably achieved when freeway speeds are dependably maintained between 41 mph and 52 mph. Figure 4 represents the speed flow curve and depicts the relationship between vehicle speeds and vehicle flow in the I-405 corridor. Managing speeds on roadway facilities in a range that maximizes flow can help manage recurrent congestion. Figure 4 - Speed-Flow Curve for I-405 The effect of collisions and congestion on roadway facilities results in a reduction of roadway capacity. Congestion contributes to the incidence of collisions (rear ends, sideswipes) and collisions compound and contribute to congestion. Figure 5 shows the relationship between rear end collisions, congestion occurrences, and the hours of delay on I-5 between Vancouver, Washington and the Canadian border. As can be seen, congestion and rear end collisions are highly correlated and focused in the Puget Sound region. Not surprisingly, the Puget Sound region also has the greatest hours of delay and traffic volumes. Again, where we most need freeway facilities to function at their highest potential, they experience the greatest degradation in capacity. Reducing collisions and related congestion can also improve our ability to manage non-recurrent congestion and improve the efficiency of our existing roadways. This study will assess active traffic management strategies for their ability to address congestion and collisions and the feasibility of implementing these strategies in the Puget Sound region. Active Traffic Management Feasibility Study 9

15 Figure 5 - Rear-end Collisions, Congestion and Hours of Delay (Northbound I-5) Active Traffic Management Feasibility Study 10

16 3.0 Active Traffic Management Techniques The Washington State Department of Transportation has actively managed the state and interstate roadways and HOV system in the Puget Sound region for approximately 20 years, by providing real-time information, metering ramps, and managing incidents, among other activities. However, there are a number of techniques being used in Europe that could complement and extend WSDOT s capabilities to maximize roadway capacity and increase safety. The following is a brief description of each of the ATM techniques assessed as part of this feasibility study. Speed Harmonization to dynamically and automatically reduce speed limits approaching areas of congestion, accidents, or special events. Benefit - to maintain flow and reduce risk of collisions. Speed harmonization signing in the Netherlands (Dutch Department of Transportation). Queue Warning to warn motorists of downstream queues and direct through-traffic to alternate lanes. Benefit to effectively utilize available roadway capacity and reduce the likelihood of speed differentials and collisions related to queuing. Junction Control to use variable traffic signs, dynamic pavement markings, and lane use control to direct traffic to specific lanes (mainline or ramp) based on varying traffic demand. Benefit to effectively utilize available roadway capacity and manage traffic flows to reduce congestion. Junction control in the Netherlands. (Managed Lanes in the Netherlands, AVV Transport Research Center, Ministry of Transport) Hard Shoulder Running to use the shoulder as a travel lane during congested periods or to allow traffic to move around an incident. Benefit to minimize recurrent congestion and manage traffic during incidents. Hard shoulder lane in England. (UK Highways Agency) Active Traffic Management Feasibility Study 11

17 Dynamic Rerouting to change destination signs to account for current traffic conditions. Benefit to effectively utilize available roadway capacity by redirecting traffic to less congested facilities. Dynamic route information displayed on VMS in the Netherlands. (Active Traffic Management: The Next Step in Congestion Management, FHWA-PL , March 2007) Traveler Information to provide estimated travel time and other condition reports to communicate travel and traffic conditions. Benefit to allow for better pre-trip and en-route decisions by travelers. Travel time signs in Germany. (State of Hessen Germany) The following section discusses the study process and methodology in greater detail. Active Traffic Management Feasibility Study 12

18 4.0 Study Process and Methodology This feasibility study was completed in two phases. Phase 1 qualitatively evaluated three major transportation corridors in the Puget Sound region to determine which corridor presented the best opportunity to test ATM techniques. The second phase of the feasibility study quantitatively assessed six ATM techniques as they could be applied within the selected Phase 1 corridor and explored operational, policy and institutional issues for implementation. Additional detail on the study process and methodology is presented below. 4.1 Phase 1 As discussed previously, Phase 1 qualitatively evaluated three major transportation corridors in the Puget Sound region for their suitability to test the European ATM techniques. The following corridors were screened based on a number of criteria to determine which provided the best opportunity for further evaluation and consideration: a. Interstate 405 and State Route 167 Corridor This 40-mile route includes the 9-mile SR 167 HOT lane pilot project, managed lane data and analysis of the 30-mile I-405 segment, as well as $1.7 billion of funded improvements that will include ITS elements complementary to an ATM system. b. Interstate 90 and State Route 520 Corridors These two cross Lake Washington routes have recent data and analysis for traffic and transit investment alternatives associated with two recent environmental impact statements, as well as plans for extensive ITS elements and probable tolling (SR 520). c. Interstate 5 The replacement of the Alaskan Way Viaduct (parallel to I-5 in downtown Seattle) with a $3 billion design may require up to a 5 year closure resulting in significant redirection of 110,000 daily trips in the downtown Seattle area. Active management on I-5 as a means of coping with construction impacts may be effective. A graphic depiction of these corridors and the Central Puget Sound region is shown in Figure 6. Active Traffic Management Feasibility Study 13

19 Figure 6 - Phase 1 Corridors for Consideration The first task for Phase 1 was to develop the qualitative factors that would be used to evaluate the corridors for further quantitative analysis. In order to quantitatively assess or test various ATM techniques, the corridor chosen would need to have certain data available, as well as specific characteristics. The project team, in conjunction with WSDOT, developed the following screening criteria: 1. Data availability: Certain data are required in order to quantitatively assess the applicability and benefits of various ATM techniques. The ability to obtain traffic data for each of the corridors was assessed as part of the initial screening. Active Traffic Management Feasibility Study 14

20 2. Infrastructure: As with data availability, the existence of basic infrastructure needed to implement some of the various ATM strategies is important to consider when screening a corridor for future implementation. 3. Traffic conditions: The assessment of various ATM techniques should be done under a wide range of traffic conditions. In other words, the ATM algorithms and parameters should be robust enough to produce positive results (or non-negative results under very light traffic conditions) under almost any traffic condition. Thus, for a realistic evaluation of the impact of ATM, the selected corridor will need a wide range of traffic conditions. 4. Implementation potential: The team qualitatively reviewed each corridor for its ability to test a wide range of ATM strategies: speed harmonization, queue warning, junction control, hard shoulder running, traveler information and dynamic re-routing. In many respects, this was a culmination of all of the above listed criteria. Assessment of implementation potential involved reviewing speed, congestion, and collision patterns in each corridor for roadway segments that are most likely to benefit from potential ATM strategies. Collective judgment was used to determine if any ATM techniques could feasibly be applied to a particular segment to maximize efficiency, improve throughput (both increased corridor operational capacity and during incidents) or minimize collisions. In addition, the roadway geometry was qualitatively assessed to determine if any physical restrictions would preclude the application of the identified ATM strategy. 5. Implementation feasibility: Implementing ATM strategies may require more coordination with outside agencies, such as the Washington State Patrol (WSP), local jurisdictions, transit agencies and the Federal Highway Administration. Some ATM strategies may also require additional staffing and coordination within the WSDOT, as well as potential policy modifications. 6. Near-term construction activities: The most efficient and expedient way to implement any selected ATM strategy is to include the ATM techniques as an integrated part of not only the design of the project, but also as part of the construction activities. To increase both the likelihood of near-term implementation of ATM strategies and potential benefits from ATM, it would be beneficial if the corridor contained near-term construction activities. 7. Impact of long-term construction: Expected (qualitative) impact of planned construction on a parallel/alternate corridor: An important criterion to consider in the corridor selection is additional traffic on the selected corridor due to planned construction on alternate routes, as it presents an opportunity to take full advantage of the various ATM techniques benefits. Once the screening criteria were defined, the project team qualitatively assessed each of the corridors based on the criteria described above and a comparison matrix was completed to aid in the screening process. In addition to the screening process, each corridor was reviewed to identify areas of opportunity to implement the various ATM techniques. A brief listing of the potential applications per corridor found as part of the Phase 1 qualitative review is provided below. I-5 I-5 has perhaps the best opportunities for speed harmonization and queue warning, southbound from South Everett to downtown Seattle, the express lanes, southbound from Boeing Field to South Center Hill, and northbound from the Active Traffic Management Feasibility Study 15

21 Corson/Michigan interchange to downtown Seattle. The possibility also exists to implement hard-shoulder running through downtown Seattle, which is being studied as part of the I-5 Pavement Reconstruction and Bottleneck Improvement Projects. The greatest number of opportunities for Traveler Information and Dynamic Re-Routing, a total of six locations throughout the central Puget Sound area, were identified on I-5. I-405/SR518 The project team identified five opportunities for speed harmonization and queue warning in both the north and south ends of the corridor and an independent queue warning location at the SR 167 interchange. Three opportunities for hard shoulder running were noted in the north end of the corridor, two in the southbound direction and one in the northbound direction. Opportunities for junction control were found between the SR 518/North Airport Access ramp and the I-405/SR 167 interchange, while traveler information and dynamic re-routing opportunities were found at the major roadway interchanges of I-5, I-90, SR 520 and SR 522. SR 167 Three locations for hard-shoulder running were identified by the project team, all of which were in the central portion between SE 180 th Street and S 277 th Street. The project team identified fewer locations for speed harmonization, queue warning and junction control, but did identify four locations for traveler information and dynamic re-routing, two of which were at the outer edges of the greater Puget Sound region at SR 18 and I-90 and SR 512 and I-5. I-90 The project team identified most ATM opportunities on I-90 in either the Issaquah or Mercer Island areas. I-90 presented fewer speed harmonization opportunities than I-5 or I-405, but slightly more than SR 167, with both east and westbound opportunities in Issaquah and east and westbound opportunities approaching Mercer Island. Hard shoulder running opportunities were identified in the Issaquah and Mercer Island areas as well. I-90 presented two traveler information and dynamic re-routing opportunities and a possible junction control opportunity at SR 519/I-5. SR 520 The project team identified the most junction control opportunities on SR 520 with a total of three: the I-5 ramps to eastbound SR 520, the eastbound Montlake on-ramp, and the eastbound West Lake Sammamish Parkway on-ramp. Two locations for speed harmonization and traveler information and dynamic rerouting were identified, the least of all corridors reviewed, and no hard shoulder running opportunities were identified. Based on the screening process and the identification of potential opportunities, I-405 appeared to be the corridor most suited for further quantitative analysis of ATM techniques, with I-5 being the next highest rated corridor. However, there was not a wide variation in rating between the corridors, revealing that all corridors had locations and conditions that would be conducive to implementing ATM strategies. For example, I-5 presented the largest number of locations for implementing speed harmonization; SR 520 had a number of locations for junction control, I-90 and SR 167 both presented interesting possibilities for hard-shoulder running. The study team then presented the screening results to representatives from WSDOT, FHWA, team members from the I-405 and SR 520 project offices, the WSP, FHWA, PSRC and others. The workshop participants also rated I-405 as first and I-5 as second in providing opportunities Active Traffic Management Feasibility Study 16

22 to test and implement ATM techniques. The group then discussed the rating results and noted that I-405 may present the best short-term opportunities, but the largest benefit of ATM implementation may ultimately be realized on I-5. The group also reiterated that implementation of ATM techniques at the system-wide level would lead to greater efficiency and safety improvements in the Puget Sound region. 4.2 Phase 2 Phase 2 of this project undertook a quantitative evaluation of the various techniques on I-405, particularly between I-5 in the Southcenter area and I-90 at Factoria. While the quantitative evaluation will be specific to I-405, the merits and quantitative benefits of each ATM strategy can be qualitatively applied to other corridors. The quantitative analysis for Phase 2 included the development of: concept level design, signing and operating plans for each ATM technique; micro-simulation of the ATM techniques as appropriate; conceptual benefits estimation; conceptual cost estimates, and conceptual operations and maintenance costs. The study team based the concept level design and operations on European approaches and an understanding of the local roadway and traffic conditions within the study area. Design and operations strategies were developed for each ATM technique, tailored to each location s unique roadway, traffic and known operational factors or issues. In most instances a variety of designs were developed to account for the European approach and for a more traditional US-based approach. Micro-Simulation and conceptual benefits estimation Micro-simulation modeling was undertaken to estimate the conceptual benefits of the various ATM techniques. The study team used a VISSIM model developed as part of the I-405 Corridor Program, which included the entire I-405 corridor (general purpose lanes, HOV lanes and ramps), from the northern boundary at I-5 to southern boundary at I-5. The basic model parameters were not changed for the purpose of this study, but the model was coded to reflect the various ATM strategies. Not all of the ATM strategies could be modeled, such as dynamic rerouting, traveler information and hard shoulder running. However, algorithms and modifications for speed harmonization, queue warning and junction control were coded into the model and run for results. The initial modeling results were reviewed and the algorithms and coding refined to obtain conceptual level results. To better quantify the accident reduction benefits realized in Europe, a series of blocking incidents were coded into the VISSIM model to determine the amount of delay reduced by the avoidance of collisions. For the purposes of this study only the reduction in primary collisions was considered. The European experience has shown that a reduction in collisions to fall anywhere between 15 and 40 percent of total collisions. After consideration of the European experience, the project team applied injury reduction rates between 15 and 30 percent for injury and property damage only collisions based on the ATM strategy under consideration. The estimated collision avoidance percentage rates were then applied to the total number of collisions within the study corridor to determine the number of collisions estimated to be avoided as a result of the ATM technique. The value of avoiding these collisions was calculated in monetary Active Traffic Management Feasibility Study 17

23 terms by multiplying the number of collisions avoided (and the type) with the National Safety Council value for collision avoidance. The National Safety Council estimates that avoiding one property-damage-only collision saves $8,200 and avoiding one injury collision saves $119,650. Additionally, the VISSIM model was used to estimate the reduction in traffic delay as a result of the various ATM strategies (where applicable and possible) and as a result of collision avoidance. Delay cost savings were developed using 2005 Washington State Employment Security Department annual employment and wage averages for King, Pierce, and Snohomish Counties to calculate value of time estimates. Value of time estimates are approximately half of the hourly average wage rate. The delay reduction estimates obtained from the VISSIM model were then multiplied by the calculated value of time estimates (estimated at $11.66 per hour). Capital cost estimates Conceptual capital cost estimates were developed using a variety of sources including FHWA s ITS Unit Costs Database, historical ITS estimate data from WSDOT Northwest Region, and product manufacturers and distributors including: Lighting Group Northwest (sign structures); Smart Stud Systems (in ground flashers); Skyline Electronics (variable and dynamic signs); and Daktronics (variable and dynamic signs). The costs cover two main categories: materials purchase and installation; and software purchasing and implementation. Construction and design factors were added to the estimates to create a cost estimate for each prototypical technique. These factors include: traffic control; mobilization; construction contingency; construction engineering; sales tax; and preliminary (design) engineering. The conceptual cost estimates for the selected I-405 corridor study, while representative of general cost estimates, cannot be directly applied to other corridors without consideration of roadway factors, such as the number of lanes, the presence and condition of shoulders, the presence of existing electricity/fiber, the presence of structure, walls, or soil conditions, etc. Additionally, including ATM techniques with a planned construction project could reduce the amount of up-front costs (advertising process, plan review, etc.), as well as cost savings with a single mobilization and combined construction management efforts. These estimated savings do not include general economies of scale type savings when several projects are combined, nor the savings from shared per mile costs for items like trenching. Operations and maintenance cost estimates Conceptual operations and maintenance costs were based on WSDOT s ITS Maintenance database of estimated annual costs for the various systems including variable message signs, changeable message signs, communication hubs, and closed circuit television cameras. The estimated maintenance costs are based on information received from WSDOT s Northwest Region Maintenance personnel. Pay scale and equipment costs have been roughly adjusted to year 2007 rates. In addition, the operations and maintenance costs included staffing costs for expanding the TMC operations to 24 hours a day, seven days per week. Finally, a qualitative assessment of the operational, policy and institutional issues surrounding implementation of the six assessed ATM techniques was also undertaken by the study team. After the initial assessment was complete, the study team presented the results in a workshop format to representatives from WSDOT, FHWA, the I-405 project office, the WSP, FHWA, and PSRC. This workshop served to validate the concept level design and operations plans, conceptual cost estimates, and implementation issues, as well as identify other considerations, costs and issues not considered by the study team. Active Traffic Management Feasibility Study 18

24 The following sections discuss each ATM technique in greater detail, providing background information; detail the concept level design; signing and operation plans; the estimated capital, operating and maintenance costs; and the anticipated benefits for each ATM technique as it applies to the selected study area. Each ATM section also includes an assessment of the potential operational and policy level implementation issues. The institutional issues span all ATM techniques and are discussed separately in Section 12. Active Traffic Management Feasibility Study 19

25 5.0 Speed Harmonization Germany has used speed harmonization since the 1970s with the focus on improving traffic flow based on the prevailing conditions. It is typically deployed on roadways with high traffic volumes. In Denmark, speed harmonization is referred to as variable speed limits, and it is used to manage congestion during construction projects. Used for many years in the Netherlands, some deployments have been implemented during adverse weather conditions (e.g. fog), while others have been used to create more uniform travel speeds. The lane control displays are used for incidents, maintenance and construction. In 2001, England introduced a pilot in response to motorists demands for better service within the realistic limitations of widening and expanding the roadway network. Variable Speed Limits on I-90 over Snoqualmie Pass Since 1997, WSDOT has implemented and managed variable speed limits to account for changing and severe weather conditions, one of the few variable speed limits (VSL) in the entire nation. WSDOT has found the VSL to be very effective in creating a uniform traffic speed that increases the safety of travelers going across the pass. 5.1 Design Concepts The application for I-405 would be to install the system from I-90 south to I-5 (in the northbound and southbound directions). Sign spacing (either overhead or groundmounted signs) would be approximately every one-half mile. This translates into a total of 50 sign bridges/ground-mount signs for the 12-mile section of roadway. Providing this spacing allows the motorist to see a consistent message because there is always an overhead sign bridge in view. The message is reinforced because it is posted in constant intervals. Figure 7 shows the German approach with speed and lane control displays mounted overhead and side-mounted iconic signs and is characterized as Design Concept 1. The lane control displays would provide the additional functionality to use this to manage incidents or address maintenance during nighttime hours. In the Netherlands, lane control displays are used for incidents, maintenance, and construction. In advance of an incident (perhaps two gantries upstream), they use a cocked arrow to move traffic out of the lane. Figure 7 - Speed Harmonization: Speed, Lane Control & Icons Active Traffic Management Feasibility Study 20

26 Figure 8 shows an alternative overhead sign bridge design with more traditional speed limit signs and lane control displays coupled with a VMS to provide traffic condition information (Design Concept 2). Figure 8 Speed Harmonization: Speed, Lane Control and VMS Figure 9 illustrates a low-cost alternative for speed harmonization. This is Design Concept 3, and entails post-mounted variable speed limit (VSL) signs on each side of the roadway. Figure 9 Speed Harmonization: Post-mounted Variable Speed Limit Signs 5.2 Capital, Operations and Maintenance Costs Design Concept 1 is the most expensive and is estimated to cost $4.7 million per mile for a corridor total of $56 million (I-405 from SR 518/North Airport Access to I-405/I-90 interchanges). Design Concept 2 is projected to cost $3.5 million per mile or $42 million for the corridor. Careful consideration should be given to the sign bridge design as it is a key element in the system cost; monotube gantries tend to be expensive, while slimmer designs may be more cost effective. However, slimmer sign bridge designs may limit sign maintenance options, with a corresponding increase in maintenance costs due to lane closures and traffic control needs. Design Concept 3 is the least expensive concept and is estimated to cost $1 million per mile or $12 million for the entire corridor. Speed harmonization is expected to require 24 hours a day, 7 days per week operation. The WSDOT currently operates its Traffic Systems Management Center 24/7, but only has traffic system operator staffing approximately 13 hours per day during the weekdays and eight hours per day on the weekends. Operation of a pilot system in the study corridor (I-405 from Factoria/I-90 to Tukwila/I-5), if operated 24/7 is expected to require an additional 11 hours of operator coverage per day on the weekdays and two additional 8-hour shifts per day on the weekends. Active Traffic Management Feasibility Study 21

27 Conceptual level costs for the maintenance and operation of the speed harmonization system designed for this study is estimated at $464,000 per year for Design Concepts 1 and Benefits Assessment The European experience has revealed a potential to decrease injury collisions by 30 percent and other collisions by 16 percent 1, resulting in 586 fewer collisions during a three-year period. Potential Savings in Delay = Potential Savings in Avoidance = Potential Total Cost Savings = $275,000/yr $13,335,000/yr $13,610,000/yr Preliminary cost estimates for the speed harmonization design concepts ranged from $1.1 million per mile to $4.7 million per mile. Comparing the most expensive design concept of $56 million with the potential cost savings of $40.8 million (in three years) shows that the system capital cost can be recovered in a little over four years. 5.4 Operations Assessment Having originated in Europe, the application of using these new ATM techniques in the Puget Sound region poses a number of operational, and policy issues that will require further consideration. In order to fully assess the feasibility of implementing the ATM techniques discussed above, the operational and policy issues were discussed in greater detail in two workshops. During the workshops, the ATM techniques were presented to groups of individuals well versed in transportation policy and the operational aspects of managing the Puget Sound region s roadway facilities. Attendees of the workshop included representatives from WSDOT traffic and design, FHWA, Puget Sound Regional Council, I-405 project team, and the WSP. Discussion of the most relevant operational issues for speed harmonization is presented below Operations The study recommends that the implementation of a speed harmonization system should have the flexibility to be either advisory or regulatory, allowing for the use of the system of signs for many different conditions (congestion, maintenance, weather-related, etc). Currently, the variable speed limit on Snoqualmie Pass is regulatory. If speed harmonization is to be used all the time, the post-mounted regulatory speed limit signs would need to be removed or replaced with a variable speed limit sign that will reflect the speed indicated on the gantries. Speed reductions could be discrete, like 60 mph, 45 mph, and 35 mph, or could be reduced dynamically based on the system algorithm. The recommendation of this study would be to reduce speeds using discrete speeds that drivers will be familiar with to improve driver compliance and avoid confusion. Consideration should also be given to when the speed limit is displayed by defining upper and lower speed thresholds. If the overhead speed limit signs are illuminated at all times, motorists may tend to ignore them, reducing the system s effectiveness. Therefore, the recommendation of this study would be to illuminate the overhead speed limit displays only when conditions warrant. While the system would primarily be used for recurrent congestion during the day and for maintenance and construction at night, the system could be used at all times for collisions, incidents, inclement weather and events. Signing the HOV or HOT lane at a different speed than the adjacent general purpose lanes should be carefully considered prior to implementation. There are inherent safety issues with Active Traffic Management Feasibility Study 22