Analysis of Freeway Improvements for Express Bus Service

Document Type

Journal Article

Publication Date


Subject Area

operations - traffic, infrastructure - vehicle, infrastructure - bus/tram lane, ridership - forecasting, ridership - forecasting, place - urban, mode - bus, mode - carpool


Urban areas, Travel forecasting, Traffic simulation, Traffic forecasting, San Francisco Bay Area, Performance, Paramics (Computer model), Motorways, Microsimulation, Improvements, HOV lanes, High occupancy vehicle lanes, Freeways, Express buses, Controlled access highways, Case studies, Carpool lanes


In many urban areas, high-occupancy vehicle (HOV) lanes have been provided to permit carpools and express buses to bypass congestion and offer a significant travel time advantage to commuters willing to share a ride or take transit. In many locations, however, HOV lanes are incomplete because of difficulties in securing right-of-way or funding. In other locations, because existing HOV lanes are underutilized, express buses are undersubscribed, or both, questions about their value arise. In this research it is shown how a PARAMICS microscopic traffic simulation model can be used to analyze proposed HOV lanes and their effects on express bus operation along an urban freeway corridor. A PARAMICS application is developed for Interstate 580 in the San Francisco Bay Area and used to test alternative ways of providing HOV lanes. The performance of the corridor is evaluated under plausible scenarios of traffic growth. Traffic simulation models are usually used for detailed operations management. The case study shows that traffic simulation can be an effective preliminary planning and scenario testing tool for evaluating the likely performance of an infrastructure or operations improvement on express bus service.