Citation

Dobrota N, Stevanovic A, Mitrovic N, Alshayeb S, Zlatkovic M. Transp. Res. Rec. 2023; 2677(1): 1337-1355.

Copyright

(Copyright © 2023, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

10.1177/03611981221104460

PMID

unavailable

Abstract

Emerging high-resolution datasets allow for developing traffic signal performance measures (TSPMs) which can provide a better understanding of traffic signal operations. One of the specific objectives of signal operations is related to the measurement of capacity utilization. A fundamental measure for capacity utilization is the ?degree of saturation? (DS), and it has both volume-based and occupancy-based formulations. The former is known as ?volume over capacity ratio? (V/C), whereas the latter is known as ?green occupancy ratio? (GOR). When V/C is used to observe capacity utilization, it is not known whether the capacity is utilized from interrupted flow, free flow, or a combination of two. Similarly, the amount of time in the cycle utilized by volume (characterized with the first and last vehicle arrival time) is not revealed within V/C. On the other hand, GOR?overlooks? cases when a high number of vehicles travel without stopping or fewer vehicles depart the signal with significant startup delays and similar. In addition, because of a lack of scientific attention, GOR has often been misinterpreted as some similar, yet different TSPM. Therefore, if only V/C or GOR are used to monitor signal performance, the understanding of utilized capacity will be incomplete or misleading. This study proposes three TSPMs: ?queued volume in volume to capacity ratio? (QViV/C), ?cycle utilization? (CLU), and ?volume-occupancy capacity utilization? (VOCU) to overcome the limitations of V/C and GOR. Also, by evaluating existing occupancy-based measures, it was found that they can be used to estimate capacity utilization, including oversaturated conditions.

Language: en