Texas Transportation Institute

Texas Transportation Institute homepage

This project summary report summarizes the research performed in Texas Department of Transportation (TxDOT) Project 0-4813. In order to help prevent crashes on freeway-to-freeway connector ramps, this project examined the potential effectiveness in reducing truck and passenger car speeds at freeway connector curves using a dual-advisory speed signing concept (with a differing advisory speed for trucks than for cars) and a novel pavement marking treatment using sets of converging chevrons. Researchers conducted surveys, focus groups, and deployments of the signing and pavement markings. The dual-advisory speed signs had a positive impact on operations and safety at the study sites. A majority of the sites tested had reductions in average car and truck speeds along the connector ramp, increased compliance with the posted advisory speed, and/or reductions in speed-related crashes. The dual-advisory signs should be considered on freeway-to-freeway connector ramps where there has been a demonstrated truck crash experience over time and where the engineer feels that truck-specific warning is warranted. The converging chevron pavement markings caused a reduction in speed on the approach to the chevron markings and at the start of the freeway-to-freeway connector curve. Researchers recommend that TxDOT consider the use of converging chevron pavement markings on only the most critical freeway-to-freeway connector ramps with certain specific characteristics, preferably after traditional mitigation measures have been implemented.