Interactions between basic road segments and the intersections by the investigations of the space mean speed

  • contact:

    Prof. Dr.-Ing. Peter Vortisch
    Dipl.-Ing. Martin Hartmann

  • funding:

    The Federal Highway Research Institute (BASt)

  • partner:

    TU München, Lehrstuhl für Verkehrstechnik

  • start:


  • end:



In everyday traffic, each node (on-ramp, off-ramp or weaving section) brings an inevitable change in the characteristics of the traffic flow. The usual consequences of oversaturation are reduced average travel speeds, higher traffic densities and in extreme cases congestions. The methodology for the evaluation of freeway facilities is given in the new HBS 2015 (Handbuch für die Bemessung von Straßenverkehrsanlagen). This approach determines the average car journey speeds on a series of highway segments and intersections and focuses on their distribution during the traffic peak times where the chance of congestions creation is high. Disadvantages of the proposed method are following - first, the average car journey speed can be only determined on network sections in the time span, during which there is no congestion at any part of the segment. On the other hand, there are conceivably ramp- or weaving-sections´ influences that could remain undetected under this methodology.

Solution approach:

The goal of the project is to determine the average car journey speed and other related traffic flow characteristics on chosen highway segments in Germany, with respect to the influence of on- and off-ramps as well as the weaving sections. Furthermore a simulation software concept will be created and applied over the chosen sections. This software should be capable of evaluating the level of service on intended sections during desired time periods, with special focus set on the conditions at the boundary between LoS E and F (representing the capacity), as described in HBS 2015.  As an input for this evaluation it is first necessary to identify adequate highway segments and collect all appropriate data. Moreover, a number of test simulation will be created, to reflex the diverse segment and ramp conditions in the network and to calibrate the required simulation parameters for the use in the real network. The findings out of this project would serve as an input for the new edition of the German Highway Capacity Manual (HBS) as well as the Guidelines for Integrated Network Design (RIN).