AGENDA #5g
MEMORANDUM
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TO: |
Roger L. Stancil, Town Manager |
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FROM: |
George Small, P.E., Engineering Director K. Stephen Spade, Transit Director Kumar Neppalli, E.I.T., Engineering Services Manager |
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SUBJECT: |
Report on Transit Signal Priority Capability in the Traffic Signal System Upgrade Project |
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DATE: |
June 9, 2008 |
PURPOSE
The purpose of this report is to provide background information and planning level cost assessment for adding Transit Signal Priority (TSP) capability to the expansion and rehabilitation of traffic signal system currently under design.
We do not recommend including Transit Signal Priority capability during the initial deployment of the new signal system software project. We plan to conduct a detailed operational evaluation study of the system to evaluate specific benefits on several major transit routes in the Town and detailed cost estimates for implementation. The TSP capability can be added to the new signal system software in the future on a specific transit route corridor or multiple transit corridors depending on available funding.
At the Town’s request, the State has approved funding in the 2007-2013 Transportation Improvement Program for rehabilitation and expansion of the Chapel Hill traffic signal system. A Municipal Agreement was executed between the Town and the State in June 2007. The project design was started in November 2007 and is expected to be completed in December of this year. The construction of the project is expected to start in April 2009 and be completed in 2011. The total estimated cost of the project is $5 million and the Town’s share is $450,000.
In addition to the traffic signal system, the Town is hoping to undertake an upgrade project, including fiber optic communication cable, closed-circuit television (CCTV) equipment at 12 selected locations in the Town, pedestrian countdown displays at locations with existing pedestrian signals, replacement/upgrade of existing cabinets and controllers, new/revised signal phasing at selected locations, emergency vehicle preemption at selected locations, bicycle activated loops at selected locations, and Transit Signal Priority (TSP) on selected corridors (if desired by the Town).
TSP is an operational strategy that facilitates the movement of transit vehicles through traffic-signal controlled intersections. Transit signal priority systems use sensors to detect approaching transit vehicles and alter signal timings to improve transit performance. For example, some systems extend the duration of green signals for public transportation vehicles when necessary. Objectives of TSP include improved schedule adherence and improved transit travel time efficiency while minimizing impacts to normal traffic operations. TSP systems have been shown to reduce certain exhaust emissions and reduce travel time on a per route basis.
There are three systems that must be interfaced to have a fully functional TSP system: the bus management system, the priority call system, and the traffic control system. The signal system project design consultant completed a preliminary assessment report of the TSP including a planning level cost assessment. A copy of the report is provided in Attachment 1. The total estimated cost of the three systems cited above varies from approximately $250,000 (one corridor with 10 traffic signals) to $1.12 million (Town wide, 120 signals). The Town (and possibly its transit stakeholders) would be responsible for providing the required funds if we chose to implement TSP capability in the signal system project. Maintenance funds are also required each year to maintain and upgrade the TSP system elements.
We note that the proposed signal equipment to be installed in the field as part of the upgrade project is capable of providing TSP operation. However, a separate software module is required to be integrated with the new signal system software to provide TSP function.
We think that a detailed operational evaluation study should be conducted before implementing TSP function into signal system to evaluate:
We plan to conduct and complete this study in the fall of this year. We will provide a follow-up report in spring, 2009 to the Council with the findings and recommendations of the detailed operational evaluation study.
CONCLUSION
We think that TSP capability provides improved transit travel time efficiency while minimizing impacts to normal traffic operations. However, before integrating this into the signal system, we think that a detailed evaluation study should be conducted to find the operational benefits and challenges. The TSP function can be added to the signal system software in future if the required funding is available.
ATTACHMENTS