Adaptive Signal Control

City of Naperville

OBJECTIVE

Continued growth, an adjacent commuter station, employment centers, and frequent special events in Naperville’s downtown area created varying traffic conditions. It was necessary to provide an innovative traffic signal system that would improve the flow of traffic and reduce overall congestion along Washington Street and Aurora Avenue.

PROJECT DESCRIPTION

Hampton, Lenzini and Renwick, Inc. (HLR) worked closely with the City of Naperville on this multi-phase project to upgrade the communications, equipment, and operations of 32 signalized intersections primarily located along the heavily travelled Washington Street corridor. Along with being the traffic signal timing consultant for this project, HLR provided construction observation services for the two phases of construction. The primary goal of this project was to install and implement an Adaptive Signal Control (ASC) system to improve travel time, reduce congestion, and prolong the effectiveness of traffic signals. The system uses wireless magnetometers to monitor traffic volumes and adjust the traffic signal timings in real time. The magnetometers are installed in the pavement in a series that record traffic volumes and vehicle occupancy and relay it to the central traffic signal system. The central system software uses tested algorithms to makes adjustments to the amount of green time in each direction. This is different than a traditional traffic signal corridor optimization, which is based on a snapshot of typical traffic signal volumes and programmed fixed time-of-day timings. The typical corridor optimization is performed every five to ten years depending on the development of the area.

The City understood that this type of system had never been used in a downtown area and wanted to use this project to evaluate how an adaptive system would work. Their hope was to be a successful example of an ASC system, allowing it to become a standard solution for other similar situations. Traffic and congestion have been concerns of residents in Naperville for a long time, especially in the downtown area; installing the adaptive system demonstrated to residents that the City is listening to their concerns and are implementing innovative solutions. With the system’s ability to respond to changes in traffic patterns quickly, drivers now experience decreased delay even when traffic conditions change. This adaptive system does an excellent job of reacting to the surges in traffic that occur, especially those during the off-peak hours.

The project was completed on time and within budget.

Awards:

• 2020 American Council of Engineering Companies (ACEC) Merit Award