A practical method to estimate the benefits of improved road network reliability: an application to departing air passengers

摘要

This paper develops and applies a practical method to estimate the benefits ofudimproved reliability of road networks. We present a general methodology to estimate theudscheduling costs due to travel time variability for car travel. In contrast to existing practicaludmethods, we explicitly consider the effect of travel time variability on departure timeudchoices. We focus on situations when only mean delays are known, which is typically theudcase when standard transport models are used. We first show how travel time variabilityudcan be predicted from mean delays. We then estimate the scheduling costs of travellers,udtaking into account their optimal departure time choice given the estimated travel timeudvariability. We illustrate the methodology for air passengers traveling by car to AmsterdamudSchiphol Airport. We find that on average planned improvements in network reliabilityudonly lead to a small reduction in access costs per trip in absolute terms, mainly becauseudmost air passengers drive to the airport outside peak hours, when travel time variabilityudtends to be low. However, in relative terms the reduction in access costs due to theudimprovements in network reliability is substantial. In our case we find that for every 1 Euroudreduction in travel time costs, there is an additional cost reduction of 0.7 Euro due to lowerudtravel time variability, and hence lower scheduling costs. Ignoring the benefits fromudimproved reliability may therefore lead to a severe underestimation of the total benefits ofudinfrastructure improvements.