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

Eric Kroes, Paul Koster*, Stefanie Peer

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


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

Original languageEnglish
Pages (from-to)1433-1448
Number of pages16
Issue number5
Publication statusPublished - Sept 2018


The authors would like to thank the editor and two anonymous referees for their insightful and constructive comments that helped improve the paper. Paul Koster gratefully acknowledges the financial support of the ERC (Advanced Grant OPTION # 246969).

FundersFunder number
Seventh Framework Programme246969
European Research Council


    • Accessibility
    • Airport access
    • Travel time variability
    • Value of reliability


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