The Influence of the Volume–Delay Function on Uncertainty Assessment for a Four-Step Model

  • Olga Petrik
  • Filipe Moura
  • João de Abreu e Silva
Part of the Advances in Intelligent Systems and Computing book series (AISC, volume 262)


This work analyzes the impact of volume–delay function inputs and parameters on the uncertainty of a four-step model traffic forecasts by link and identifies the relevant major error contributors. For that different specifications of the volume–delay function (including its choice and parameters probability distribution) and road capacity as an uncertain element of the input are considered. The uncertainty is expressed in form of variance of the link flows forecast provided by the model for different links types. To illustrate the analyses, a case study data from Aveiro, a medium sized city in Portugal, is used. The results suggest that the capacity variation has higher impact on the final uncertainty (up to 6 % of the coefficient of variation in average for all types of links) than the volume–delay function parameters (up to 3 % of the coefficient of variation) and the links with lower speed limits are affected most.


Uncertainty analysis Four-step model Volume–delay function 



This research was developed in the framework of the EXPRESS Research Project (MIT/SET/0023/2009) sponsored by the Portuguese national research funds through FCT/MCTES (PIDDAC) and co-financed by the European Regional Development Fund (ERDF) under the Operational Agenda for Competitiveness Factors—COMPETE. We acknowledge the collaboration of the Municipality of Aveiro that allowed the use of the mobility survey data. This survey was performed by the transportation consultants Way2Go for the Aveiro’s Urban Mobility Plan. We are grateful to an anonymous EWGT referee for comments that helped to improve this chapter.


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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Olga Petrik
    • 1
  • Filipe Moura
    • 1
  • João de Abreu e Silva
    • 1
  1. 1.CESUR/DECivil, Instituto Superior TécnicoTechnical University of LisbonLisbonPortugal

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