A Model of Car-Following Behavior at Sags

  • Bernat Goñi Ros
  • Victor L. Knoop
  • Wouter J. Schakel
  • Bart van Arem
  • Serge P. Hoogendoorn
Conference paper


Sags are bottlenecks in freeway networks. The main reason is that the increase in slope has a negative effect on vehicle acceleration, which results in local changes in car-following behavior that reduce traffic flow capacity. Existing car-following models are not able to reproduce the acceleration behavior of drivers at sags and the resulting traffic flow dynamics in a sufficiently realistic way. This paper presents a new car-following model that aims to fill that gap. The model assumes that drivers have a limited ability to compensate for the negative effect that an increase in gradient has on vehicle acceleration. Compensation is assumed to be linear over time; the maximum compensation rate is defined as a parameter. The paper presents the results of a case study using the proposed car-following model. The study site is a particular sag in Japan. Similar traffic flow patterns are observed in simulation and in empirical data from that site. In particular, the model generates a bottleneck caused by the increase in freeway slope, reproducing its location very accurately.



This research was sponsored by Toyota Motor Europe.


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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Bernat Goñi Ros
    • 1
  • Victor L. Knoop
    • 1
  • Wouter J. Schakel
    • 1
  • Bart van Arem
    • 1
  • Serge P. Hoogendoorn
    • 1
  1. 1.Faculty of Civil Engineering and GeosciencesDepartment of Transport and Planning Delft University of TechnologyDelftThe Netherlands

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