Traffic Signal Optimization

South Bend, Indiana

The city of South Bend established an Energy Efficiency Conservation Strategy Plan to help manage/reduce their annual energy bill of $6.8 million per year. Our firm was contracted to enhance transportation energy efficiency through traffic signal timing synchronization of the 100 busiest signalized intersection corridors in South Bend. To meet this goal, several tasks were undertaken to arrive at a recommendation.

Tasks included:

• Assessment of Existing Signal Systems - A formal assessment of the existing traffic signals and signal systems was conducted as part of this traffic signal optimization project. The assessment included field visits to the study intersections, site visits to the Aries server, and review and evaluation of data collected from the field, previous studies, and City records.

• Data Collection – Our specialists collected three types of data for this traffic signal optimization project: pre-implementation traffic signal timings, traffic volumes, and vehicle travel times on the study corridors before and after implementation.

• Analysis of System - The existing traffic data, field observations, and calculations using Trafficware’s Synchro software were all used to determine the new traffic signal timings for both the downtown grid and for five other corridors outside the downtown area.

• Implementation of New Traffic Signal Timings - After determining the optimized traffic signal timings, proposed traffic signal system timing sheets were developed and the timing data were entered into Aries in preparation for download to the signal controllers. The signal timing data files were then downloaded and programmed into the signal controllers in the field at each of the study intersections by the project team, assisted by City personnel. The consulting team aided in field observations and making any necessary minor timing adjustments to improve traffic flow.

• Post-Implementation Analysis - Once the new traffic signal timings were programmed into the controllers at each of the study intersections, further analysis was performed to determine the impact of the new traffic signal timings on fuel consumption, emissions, and delay.

• Staff Training of the Aries System - One of the project tasks was to train the city of South Bend staff how to better use and leverage the Aries system to the benefit of the City. City staff already knew how to do minor inquiries into the Aries database; however, understanding the full functionality of the software allows for troubleshooting many issues without having to make a special trip out into the field. This is especially important with the dwindling budgets that many municipalities are experiencing today. Using the Aries system effectively means that people can run larger systems.

The results of the traffic signal optimization were encouraging, especially considering the additional delay that was introduced to the study corridors by increasing the pedestrian crossing times to conform to current MUTCD requirements