Overflow delay in signalized networks

Traffic arrivals tend to be random at signals near to the perimeter of a network (or near to traffic generators in a network). Within the signal network, however, surges in traffic demand are reduced due to limitations on the amount of traffic passing through intersections imposed by signals, resulting in more uniform arrivals from cycle to cycle. Such uniformity is a desirable property at signals as underutilization of green periods may be reduced and levels of service improved. This may have serious implications within networks where it may be possible to improve the capacity of critical intersections by the strategic placing and timing of signals at less critical locations. The analysis of such options is, however, restricted by most, if not all, of the currently available evaluation methods. Relatively simple modifications of delay formulae are proposed to overcome these restrictions.