Highway Planning and Operations for the Dallas District: Freeway Operations Under Congested Conditions (7-1994-11)

Freeway bottlenecks are a primary source of congestion, and the removal of several bottlenecks in Dallas has shown a favorable reduction in delay. Solving a freeway bottleneck can be highly complex, and existing analytical tools have been inadequate for congested conditions. Driving behaviors in congestion were observed at several sites on freeways in Dallas and include queue jumping, weaving in congestion, and shoulder driving. These observations have furthered the understanding of freeway operations in congestion.A survey of what other agencies are using to simulate congested freeway operations showed that FRESIM is the most widely used simulation tool. Several adaptations to the use of FRESIM were identified and tested. These refinements to the application of the FRESIM model allow for better analysis of congestion and bottleneck improvements.Assessing the benefit a bottleneck removal provides to the motorists remains incomplete. In cases where the bottleneck is simple and well-defined, benefits may be fairly easy to estimate. However, the benefits to motorists are not always obvious. This research enhances the reliability of bottleneck improvement benefits by identifying options to the traditional methodology for assessing benefits.