Comparison of an adaptive signal system to time based coordination plan along a signalized arterial

Field evaluation of adaptive signal control technologies (ASCT) is important in assessing its contribution to operational efficiency of intersections. ASCT systems can respond to traffic volume changes, thus it could potentially outperform a time-based signal coordination (TBC) plan. This paper compares the operational efficiency of SynchroGreen, an ASCT system, to a TBC plan (called base case) on an urban arterial. The ASCT performance was evaluated based on combined analyses of the changes in volume, delay, and queue length. For the combined analyses, a performance indicator (PI) was determined whether traffic operation was significantly Improved, Unchanged, or Deteriorated (with 91% confidence level). Among the 56 lane groups (approaches), the PI improved in 5% of lane groups (3 cases), unchanged in 32% of lane groups (18 cases) and deteriorated in 63% of lane groups (35 cases). Out of the 35 deteriorated cases, volume significantly increased in 3, did not change in 21, and decreased in 11. The 3 deteriorated cases may be attributed to the system’s inability to respond to volume increase adequately; however, for the 32 lane groups in which volume did not increase significantly, the deterioration in PI was not expected. The TBC plan on this corridor was running very efficiently and SynchroGreen adaptive system did not perform as good or better than the TBC.