A Reliability-based Approach for Traffic Signal Control

An important consideration in traffic signal control is that traffic arrivals are not deterministic. The effect of stochastic arrivals in the past has been mainly dealt with by introducing stochastic terms in delay formulae. While convenient, this approach is somewhat indirect. Moreover, when the degree of saturation is high, the system becomes highly transient; it is debatable whether a static or time-invariant result in the form of a delay formula is applicable. In this study, instead of relying on steady state or equilibrium probability measures, we capture the transient effect by analyzing the state of the system from cycle to cycle based on a probabilistic treatment of overflow in an event tree. One can either use the approach to study an existing timing plan or to design a timing plan that satisfies a certain overflow reliability requirement. The advantage is that one does not need to resort to delay formulae. Some numerical results are included to demonstrate this approach. Word count: 5158 Tables + Figures: 9 Total equivalent word count: 5158 + 9*250 = 7408 TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal. 2