Intelligent Transportation Systems

In analogy to the flow of fluids, it is expected that the aggregate density and the velocity of vehicles in a section of a freeway adequately describe the traffic flow dynamics. The conservation of mass equation together with the aggregation of the vehicle following dynamics of controlled vehicles describes the evolution of the traffic density and the aggregate speed of a traffic flow. There are two kinds of stability associated with traffic flow problems - string stability (or car-following stability) and traffic flow stability. We make a clear distinction between traffic flow stability...

This report documents the development of a preliminary specification for a transit bus frontal collision warning system, based on a system engineering approach. The research efforts included: 1) a literature review, 2) detailed analyses of the five-year safety records of a group of California transit properties to identify the causes of their safety problems, 3) an in-depth data collection and analysis from instrumented buses serving San Mateo County, CA, and 4) development and testing of three generations of transit bus frontal collision warning systems, incorporating enhancements to meet...

Deployment is at the forefront of current activity in California in the field of intelligent transportation systems. It is important to understand the multitude of issues associated with such deployment to increase the likelihood of a successful deployment initiative. A review and synthesis of the literature on deployment issues have been performed. This served as a basis for development of a proposed decision-oriented framework that may be used to recognize and organize issues for the deployment of intelligent transportation systems. The applicability of this framework to intelligent...

This document summarizes the microscopic traffic simulation models used in the project entitled Using Cooperative Adaptive Cruise Control (CACC) to Form High-Performance Vehicle Streams. The major components of the microscopic traffic model include the vehicle dispatching model, human driver model and ACC/CACC model. The vehicle dispatching model determines how a modeled vehicle enters the simulation network and the distribution of different types of vehicles across the multi-lane highway. The human driver model and ACC/CACC model specify the car following and lane changing behaviors of...