The paper contrasts current views about the effectiveness of actuated signal control in urban traffic, based on a field study carried-out in Brazil, and evaluates the viability of analysis methods based on HCM performance models in predicting signal times and vehicle delays for deciding about its implementation. The authors argue that there is an old view about the use of actuated control on practical warrants (as cure for light-volume traffic signals only) in contrast to a theoretical belief on the performance superiority of actuated control (stated generically). The field study investigates the comparative performance of pre-timed and actuated control in a heavy traffic urban intersection and evaluates field measures of delay against HCM-based model estimates (a basic tool for establishing a clear criteria grounded on cost-benefit analysis). The field study shows that potential gains from actuated control are not easy to realize, depends on good parameter setting for micro-regulation efficiency and, most of all, on the importance of incidents and trends that ask for an automatic macro-regulation capability. Even for evaluating micro-regulation gains, HCM-based performance models give biased results about traffic actuated operation, commanding care on their use for assessing the real (relative) effectiveness of traffic actuated control on the field, not to say about parameter settings. The authors conclude with the identification of some research themes that can contribute in establishing better methods.
Abstract