Modelling delay saving through pro-active incident management techniques

Purpose Road traffic incidents cause delay, affect public safetyand the environment. The CEDR PRIMA project aims toextend practical guidance for traffic managers in pro-activeTraffic Incident Management (TIM) techniques to reduce theimpacts and associated costs of incidents.Methods The paper describes modelling methods used in theproject for assessing the effect of different management techniqueson incident duration and travel delay under various scenarios,including collision, adverseweather, heavy vehicle breakdownand other obstruction, assuming various management strategiesand generic impacts of novel technologies. Macroscopicsimulations of 178 variations of 13 basic scenarios have beenperformed using a flexible and computationally efficientmacroscopic queue model, results being verified by simulationusing a velocity-based Cell Transmission Model (CTM-v).Results The results of the two modelling methods are broadlyconsistent. While delays estimated by the two methods candiffer by up to 20%, this is small compared to the factor of30 range of modelled delays caused by incidents, dependingon their nature and circumstances, and is not sufficient toaffect general conclusions. Under the peak traffic conditionsassumed, the most important factor affecting delay is whetherrunning lanes can be kept open, but quick clearance of carriagewayis not always feasible.Conclusions Comparison of two very different modellingmethods confirms their consistency within the context of highlyscenario-dependent results, giving confidence in the results.Future research and data needs include further validation ofthe models, potential application to traffic flow and conflictprediction and incident prevention, and more complete andconsistent recording of incident timelines and impacts.Funding agencies; Conference of European Directors of Roads (CEDR); Highways England