Corridor Level Adaptive Signal Control

Traffic congestion in Austin Texas is becoming more problematic as the City continues growing rapidly. Current estimates indicate over 150 people per day are moving to Austin. To deal with the growing congestion problem in many travel corridors, the City is proposing adaptive traffic signal systems for several routes. The first pilot test is to be on a north-south route (Lamar Blvd) that experiences congestion particularly during the AM peak time. Before-after assessments of the proposed timing methodology will be developed from field observations and form the basis for improving the concept. The chosen corridor is an excellent test bed since it features hard-wire connected signal controllers and video surveillance. Street geometry includes two lanes each direction with a continuous two-way left turn lane. The adaptive signal technology development addressed in previous tasks offers potential for reducing traffic delay and improving travel times within the typical urban network. However, implementation of the technology in a large urban signal network usually cannot be accomplished in one step and adaptive technology may actually not be appropriate for every signal. For example, the City of Austin Transportation Department is responsible for installing and maintaining over 1000 signals and although they are interested in adaptive control they wish to have guidance regarding priorities for adaptive control implementation. Therefore, this task will develop a methodology for prioritizing the implementation process. Since adaptive technology provides enhanced responsiveness to changes in traffic demand, methodological development will consider traffic demand changes across a variety of time frames including hours, days, weeks and longer time durations as potential indicators of implementation priority. Another consideration, related to time-based coordination, is the characteristics of signal groups in which prospective adaptive controllers are located. Generally, for coordination purposes, signals in each area-wide group have common cycle lengths and constraining an adaptive controller to maintain an existing group cycle length could reduce the potential efficiency. The desired product of this task is a methodology for developing a priority order for adaptive control implementation.