In 2003, the Minneapolis Department of Public Works made a request to the Federal Highway Administration (FHWA) for help in assessing its operations. In recent years, the city of Minneapolis had experienced significant reductions in their traffic signal management and operation program, and these reductions have had a significant negative impact on the city's ability to deal with traffic congestion. The FHWA Minnesota Division engaged experts from the National Transportation Operations Coalition (NTOC) and the FHWA National Resource Center to perform the assessment. The NTOC had just completed the first draft of a self-assessment tool and was looking for test sites; the Minneapolis Department of Public Works agreed to be the pilot for the assessment in return for a thorough review of its operations.
The focus of this study is the Traffic Engineering Section of the Traffic and Parking Division of the Department of Public Works. The NTOC assessment team (a peer panel of experienced transportation officials) met with Minneapolis city personnel on February 19 and 20, 2004, and as part of their assessment, the team administered and discussed the self-assessment survey tool. The team also met with the Minnesota Department of Transportation to learn their view of the city operation.
Based on their findings, the NTOC assessment team offered the Minneapolis Department of Public Works a number of recommendations for how they might improve operations, and thus traffic conditions, in the city.
In February 2004, the National Transportation Operations Coalition (NTOC) Traffic Signal Action team utilized its recently developed self-assessment tool to provide the City of Minneapolis Department of Public Works with an assessment of its traffic signal management and operations program. The assessment team concluded that the city is working hard to keep the basic system elements running as efficiently as possible, but the city lacks a coherent program. More specifically, key findings include:
- There is no measure of system health or performance
- The current approach is reactive
- A good foundation exists
- There are inadequate personnel levels
- The regional focus is limited and opportunity exists
Based on these findings the assessment team offered a number of recommendations, presented below as a set of lessons learned.
- Adopt a performance-based approach. Currently, the city of Minneapolis does not routinely measure system performance, and it has no baselines for knowing how well the system is serving the travelers' needs. The city should institute a program of frequent, planned system performance measurement, such as a report card. This report card could include measurements such as travel times and travel time variability. It should also include how well the system components are maintained, their operational status, and how long it takes to make repairs. As part of this effort, each individual signal on critical corridors should be reviewed and updated at least every three years.
Performance measures provide a baseline for assessing system operations over time, and indicate areas where improvement is needed. In addition, performance measures can be can be used to focus limited resources on the areas that would derive the greatest benefit, and report cards detailing system performance can be a useful communication tool to share with city leaders and the public.
- Adopt a proactive approach. Rather than simply reacting to problems as they arise, the city must seek to anticipate and accommodate changes as quickly as possible. The adoption of a proactive approach goes hand in hand with a performance based approach. Through assessing all the signals in the system, it will be possible to determine the appropriate action for each, and to make adjustments before a problem arises. Actions might include signal retiming, physical modifications to improve traffic flow or other techniques to maximize efficiency. The assessment might also reveal that certain signals at less traveled intersections are not needed. Consideration should be given to the possibility that motorists might benefit by another form of right of way assignment; in addition, this would also result in costs-savings for the city.
As part of a proactive approach, the city must try to include more signal system work in its construction plans. A closer relationship with construction projects could result in more signal system work (including installation, hardware/software upgrades, updated timing) being included in construction projects. Moreover, any construction project should be required to ensure that traffic signals are in working order after the construction is completed. In Minneapolis, the SCOOT traffic adaptive signal system has been out of operation for many months due to a construction project.
In order to be more effective, the city also must develop predetermined plans of action ready to respond to situations as they develop. In Minneapolis, some of these plans exist, but they have not been used due to a lack of personnel and expertise.
Once installed, traffic signal systems must be continually monitored, and operations should be adjusted as necessary. Changes in land use, weather, the roadway network, incidents, and planned events all contribute to changing patterns, volumes and demands for service at each signalized intersection. An active, concerted effort is required to ensure that traffic signal systems are kept operating at peak efficiency. By adopting a performance-based, proactive approach, cities can more efficiently operate their systems, thus maximizing safety and mobility benefits to drivers.
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