Evaluation and Refinement of Minnesota Queue Warning Systems

Principal Investigator:

John Hourdos, Director, MN Traffic Observatory, Civil, Environmental and Geo-Engineering

Project Summary:

The formation and propagation of queues on urban freeways is an unavoidable result of the ever-increasing traffic demand. Besides the congestion increase and efficiency reduction in the transportation network system, some of these queues can cause serious rear-end collisions resulting in property damages and injuries. A recently concluded research project, "Development of a Queue Warning System Utilizing ATM Infrastructure: System Development and Field Testing," developed two systems that can identify potential queues on the mainline and generate warnings communicated to motorists upstream through the existing ATM infrastructure. The queue warning system (MI-QWARN) that was targeting standing queue and deployed on I-35W SB had little time for a detailed evaluation, so its efficacy is still unclear. In difference, the queue warning system (MN-QWARN) targeting shockwaves and traffic at the initial stage of breakdown, which was deployed on I-94 WB, has been in operation for more than a year and the initial three-month evaluation period afforded suggested a crash reduction of more than 20 percent. Unfortunately, project timing and implementation difficulties did not allow testing of different warning messages other than "Slow Traffic Ahead" in either system or any experimentation with different road sensors. Specifically, in both cases, the Minnesota Department of Transportation (MnDOT) does not regularly use the sensors employed. Research supported by the Roadway Safety Institute (RSI), has allowed the continuation of the offline development of the MN-QWARN system on I-94. The project has the following objectives: 1. Expand the evaluation of both deployed systems using all available historical data since their initial deployment day. This includes video records as well as crash reports. 2. Implement the refinements already developed for the MN-QWARN system and initiate a new evaluation period. 3. Evaluate the transferability of the MN-QWARN system by implementing it in two locations upstream of its current deployment. This will also serve as a crash reduction system during the I-35W/I-94 reconstruction project second year, which will be in full force starting April 2018. 4. Expand the MN-QWARN system implementation to use Wavetronix sensors, which are the new MnDOT preferred sensors. 5. Estimate the cost-benefit structure of the queue warning systems to assist in future deployments.

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