Document Type

Journal Article

Publication Date


Subject Area

operations - traffic, infrastructure - vehicle, planning - safety/accidents, planning - integration, land use - impacts, economics - benefits, mode - rail


Vehicle exhaust, Variable message signs, Traffic safety, Traffic queuing, Traffic flow, Traffic diversion, San Antonio (Texas), Railroad grade crossings, Motorways, Microscopic traffic flow, Level crossings, INTEGRATION (Computer model), Impacts, Highway railroad grade crossings, Highway rail intersections, Grade crossings, Fuel consumption, Freeways, Exhaust gases, Exhaust emissions, Dynamic message signs, Diverted traffic, Controlled access highways, Changeable message signs, Case studies, Benefits, Automobile exhaust


At-grade highway-railroad crossings cause traffic control problems that have a bearing not only on traffic safety but also on traffic flow efficiency. Crossings located near freeway exits pose particularly acute problems, as long closures could result in vehicle queues that spill back onto freeway lanes. A potential solution to this problem was evaluated by investigating the use of variable message signs to divert exiting freeway traffic through non-congested alternate exits. This was done using the crossing near the Fredericksburg Road exit on Interstate 10 (I-10) in San Antonio, Texas, as a case study. In the evaluation, microscopic simulation was used to determine the impacts of train operations at the crossing and the potential benefits of a variable-message sign (VMS) system installed on I-10. These effects were gauged by considering scenarios with varying levels of train duration, traffic demand on the freeway exit, and driver compliance to the displayed messages. While little network improvements were obtained, the analysis demonstrates the capability of the INTEGRATION software in analyzing such scenarios and the extent to which exiting freeway traffic may benefit from the VMS system, as well as the need to consider fuel consumption and vehicles emissions in the evaluations.