Arterial Signal Coordination with Uneven Double Cycling
Hongmin Zhou, January 2015
In arterial coordination, high traffic volume at large intersections often requires a long cycle length to achieve good two-way progression. This long cycle length, however, often causes excessive delay at some minor intersections where the traffic volume is low on cross streets. This research proposes a mathematical optimization model to enable uneven double cycling (UDC) in arterial signal coordination to address this issue. The model presents an equation for delay estimation when using double cycling and formulated a bi-objective optimization problem that maximizes bandwidth efficiency and minimize total average delay. The model introduces the concept of nominal red to describe the bandwidth geometry that is compatible with conventional arterial coordination. Through disjunctive programming techniques, the resultant model is a mixed integer quadratic programming problem with linear constraints. Based on numerical experiments evaluating the model performance, the research suggests several criteria for preliminary UDC application guidance. The UDC control scheme generally performs better at intersections with permitted left turn operation. When the arterial green time ratio between the minor intersection and the critical intersection under single cycling is greater than 2.06, the UDC control scheme is recommended for it can reduce delay without reducing bandwidth efficiency when compared with conventional single cycling. Following the preliminary guidelines, the case study using an actual field dataset showed promising results.
Keywords: Traffic Signals, Optimization, Progression, Coordination
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