Freeway control systems operate with variable message signs showing traffic actuated speed limits, no passing zones for trucks, keep-in-lane recommendations, and situation-dependent warnings. The basis for switching the different provisions up to now is a conventional multi-threshold decision table realized as procedural program. The input data are traffic data like volume and mean speed as well as environmental data, such as visibility and electrical conductivity of the road surface. Meanwhile, reliable macroscopic traffic flow models are developed that reproduce the spatial and temporal variations of the traffic variables starting from boundary and initial conditions. Since the effects of the traffic control provisions can also be reproduced by these models a real-time model comparison is possible. On the basis of this approach using the model package MAKSIM, a control strategy is designed that uses an objective function for optimum choice of the control means. The model reproduces traffic flow on edges and nodes as continuous course of volume and mean speed as input for the objective function. The objective function assesses safety and efficiency effects. For this aim speed, drops are selected and form one part of the objective function. Efficiency effects are regarded by maximizing traffic volume and mean speed, forming the second part of the objective function. The control logic with real-time model comparison is embedded in an expert system. This expert system uses the real-time model comparison as a kernel within a platform linking together all necessary additional modules, like object generator for road characteristics, for model parameters, and for control means as well as modules for communication between detector stations, control unit, and variable message signs. As test site for implementation, a line control system on the autobahn A9 in Munich is selected, which serves as a data pool and reference for comparing model-based and conventional control algorithms. A detailed evaluation of the results for different traffic situations is given. Emphasis is put on traffic patterns referring to transitions between stable and unstable traffic flow and complicated weather conditions. The results are used to estimate the effort and benefits of introducing a control logic with real-time model comparison.

  • Supplemental Notes:
    • Five volumes of papers and one volume of abstracts comprise the published set of conference materials.
  • Corporate Authors:


  • Authors:
    • Kuhne, R D
    • Csallner, A
  • Conference:
  • Publication Date: 1995-11


  • English

Media Info

  • Pagination: p. 2074

Subject/Index Terms

Filing Info

  • Accession Number: 00724455
  • Record Type: Publication
  • Report/Paper Numbers: Volume 4
  • Files: TRIS
  • Created Date: Aug 24 1996 12:00AM