The overwhelming conclusion from each of the locations studied was that there is always a means of overcoming technical and institutional barriers to cross-jurisdictional traffic signal coordination. Furthermore, in all cases, the benefits associated with improving traffic signal coordination outweighed the difficulties encountered in establishing the program.
Cross-jurisdictional signal coordination is an achievable goal for any size community regardless of the number of jurisdictions involved, the type of signal hardware and communication equipment, or even the philosophical differences in timing approaches. The most important factor in achieving coordination across jurisdictional boundaries is not the technical or equipment challenges; but cooperation, collaboration, and communication among the agencies. Partnering with agencies, either formally or informally, to manage institutional issues is key to implementing a successful cross-jurisdictional traffic signal coordination program. The following examples from case studies illustrate how some agencies have overcome institutional challenges.
- Address comfort levels when establishing formal or informal agreements among agencies. In Philadelphia, the city’s cross-jurisdictional signal program involves three agencies sharing information verbally, having established informal agreements between the jurisdictions. This arrangement has worked well for these agencies. As the agencies expanded the system, additional agreements were necessary and they found that the smaller municipalities prefer formal agreements that have been reviewed by legal counsel. It takes additional time and effort to structure agreements that satisfy the legal representatives. The agencies believe that the coordination agreements, whether formal or informal, have resulted in improved operations in terms of fewer accidents, more consistent speeds, and reduced air pollution.
- Explore alternative arrangements for cooperation that suit the local landscape. In Montgomery County, Maryland, a formal agreement between the Maryland State Highway Administration (MdSHA) and the county has been established for the maintenance of state-owned traffic signals; but there are no formal agreements to address signal timing. The county and the District of Columbia have met informally and agreed upon common cycle lengths for corridors that need to be coordinated during the AM and PM peak periods.
- In Monroe County, New York, the county is the lead agency and has formal Memoranda of Understanding (MOU) with the state and other local agencies to operate and maintain the traffic signals in all jurisdictions. The agencies have worked together to develop an Interagency Operations Plan.
- Take advantage of facilitation by regional governmental organizations. The City of Greenwood Village, Colorado has both formal and informal agreements in place for coordinating traffic signals across jurisdictions. The Denver Regional Council of Governments (DRCOG) is the lead agency and has partnership agreements with the City of Greenwood Village, the Colorado Department of Transportation (CDOT), and Arapahoe County for the development of timing plans. Each jurisdiction maintains its own traffic signals; but there is a Traffic Signal Committee that meets regularly to discuss coordination issues.
- In Tucson, Arizona, the city is the lead agency and maintains the central traffic control system. There are six other agencies that share the use of the system allowing each agency to more easily coordinate its traffic signals with the others, providing a seamless transportation system. Each develops, implements, and maintains their own timing plans and maintain their own traffic signals. There are no formal agreements for operating or maintaining the signal system, but they have a monthly forum through the Pima Association of Governments to address issues pertaining to the system. An advantage of their approach is that the participating agencies have realized cost efficiencies through pooling of the regional funding resources for the purchase and installation of traffic signal coordination equipment.
As can be seen from the above illustrations, cooperation and success can be achieved either through formal or informal agreements depending on the comfort levels of the agencies. The success of a cross-jurisdictional signal timing program depends on the willingness of the agencies to work together and can have significant impacts on system costs and performance. This will sometimes involve compromises by agencies to achieve common cycle lengths. Each involved agency must be willing to negotiate to attain the common goal of a seamless transition across boundaries. Cross-jurisdictional signal timing achieves ITS goals of improved safety, increased mobility, reduced energy requirements and environment impacts, and customer satisfaction.
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