System Optimum Dynamic Traffic Assignment Graphical Solution Method for a Congested Freeway and One Destination

In this study, dynamic traffic assignment in a network consisting of a hypothetical surface street grid and a congested freeway section is investigated in order to identify system optimum ramp metering and diversion strategies. In this network, vehicles can be diverted through off-ramps, and on-ramps can be metered. The solutions are identified graphically using Newell’s queuing diagrams. It is shown that pricing according to marginal cost would be difficult to implement in this case, that eliminating all queues from the freeway is always suboptimal, and that ramps near the bottleneck should be metered more severely. Results also suggest that during peak periods, the best course of action is to close on-ramps located near the bottleneck. Since this policy is too drastic to be acceptable to highway authorities, the lowest acceptable ramp metering rate should be deployed. The findings from this study can provide a benchmark for future intelligent transportation system applications.


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  • Accession Number: 01013303
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Dec 10 2005 12:15AM