Roads/Highways

This research project included work in several areas related to the operation of traffic signal systems in oversaturated traffic conditions. Quantitative measures were developed that characterize the intensity of oversaturated conditions and can be calculated based on high-resolution data from advance detectors and second-by-second phase timing data. The technique measures the length of the overflow queue at the beginning of the red light and estimates the amount of green time that is wasted either by dispersing this overflow queue or by vehicles that cannot proceed due to a downstream...

California’s Freeway Service Patrol (FSP) is a congestion mitigation program managed in partnership with metropolitan planning organizations (MPOs), CHP and Caltrans on California’s urban freeways. The program utilizes a fleet of roving tow and service trucks designed to reduce traffic congestion by efficiently getting disabled vehicles running again, or by quickly towing those vehicles off of the freeway to a designated safe location. Quickly removing motorists and their disabled vehicles from the freeway reduces the chances of further incidents caused by onlookers and impatient drivers....

Modeling the impact of air quality requires estimating vehicle volumes and average travel speeds in order to estimate air pollutant emissions. Relatively accurate estimates of average vehicle travel speeds can be obtained from existing traffic operations models. However, when the travel demand impacts of the highway project extend over many miles of the freeway and arterial street network, it is not feasible to apply these detailed traffic operations models to the entire area of impact because of their extensive data requirements. Planners then must resort to areawide planning models to...

This paper presents a new modeling approach in which the WATSim simulation model is interfaced with dynamic traffic assignment algorithms in order to simulate vehicles with route guidance/information systems. This enhanced model can generate origin-destination and path matrices from observed turning movement counts. It also provides comprehensive statistical, graphical and animation outputs of the vehicle movements. The model was applied to the downtown San Francisco Embarcadero network and is shown to be useful in evaluating the effectiveness of Advanced Traffic Management and Information...