SPONSOR: City of Portland, Office of Transportation (Signals and Lighting)

BUDGET: $15,000

ABSTRACT: Traditional models for traffic signal control consider all vehicles in a single class and operate in a simplified mode of operation. This mode of operation is a function of the information collected by the detection and the ability of the traffic signal controller to use advanced data. The use of video detection presents new opportunities for more strategic traffic control decisions by providing preferential treatment for freight vehicles. One reference to systems minimizing truck stops at signalized intersections was found in the existing literature. The system was developed and implemented at one signalized intersection in Sullivan City, Texas in order to address the issues connected with the increased truck traffic and resulting pavement damage, traffic delay and decreased safety at a signalized intersection. (Sunkari, Charara and Urbanik, 2001). Specifically, this system had an objective to minimize stops experienced by trucks at high-speed signalized intersections. It used loop detectors and a classifier to identify trucks approaching the intersection. This information was then used by an algorithm developed by the Texas Transportation Institute to minimize truck stops and traffic delay while improving safety, reducing pavement wear, and decreasing traffic delay. The before-after analysis showed that the system would pay for itself in less than two years (Sunkari, Charara and Urbanik, 2001). The introduction of video detection at the intersection has lead to challenges related to vehicle timing parameters and does not operate efficiently, causing delays and unnecessary stops. The large trucks using the intersection are not given sufficient time to enter and clear the intersection. The long vehicle queues block driveways to adjacent businesses. The proposed improvements include:

• Fine-tuning the operation of the existing video detection system at the intersection
• Assessing the effect of optimized timing parameters
• Exploring options and methods to provide improved operation of trucks
• Providing improved monitoring of the intersection operation through CCTV camera and special recording device
• Working with ODOT to revise the SB turn bay barrier

These changes should greatly improve the intersection efficiency. As seen in the research conducted by TTI, we expect that within one year of implementing this project, the value of user benefits will exceed the cost of the project. This project will serve as a laboratory for future studies related to signal operations improvements and freight mobility.