Assessing the knock-on effects of flooding on road transportation (article)

Abstract

Flooding can affect every aspect of our lives and road transportation is no an exception. However, the interaction between floods and transportation was not investigated closely in the past. As transportation is the lifeline of any economy, it is essential to analyse potential dangers and threads that can lead to network capacity restraints. Considering the potential of flooding to affect large areas for long durations, disruptions to transportation can result in extensive knock-on effects. To examine how flooding can impact road transportation a novel methodology was developed into a software tool which integrates flood and traffic models. The flood is simulated with InfoWorks flood model and the traffic is represented by a detailed microscopic model (SUMO), which simulates individual vehicles and their interactions. The two systems are integrated in a dynamic way, whereby changes in the flood propagation dictates the temporal variation of road network capacity restrictions. Depending on the flood characteristics, a flooded road in the traffic model undergoes either a speed limit reduction or a complete closure. Once a road has been closed for traffic, vehicles that originally pass through it are forced to choose alternative routes to reach their unique destinations. The reroute will put an additional strain on a system that is already suffering reduced network capacity. The most vulnerable roads in the network are identified after a comparison of the traffic conditions under normal and flooded situation. The results indicate that the locations of flooded streets cannot be directly associated with the most severely congested areas emphasising the significance of the knock-on effects when describing flood impacts on road transportation.