Traffic Operations and Management

Vehicle-based Control Computer Systems

Auslander, David M
1995

This report is presented in two parts: the first part describes a design and implementation methodology for real time software suitable for control of mechanical systems such as vehicles. This method provides for a design description of the system, a means of capturing the system structure in such a way as to modularize the software writing job, and a portable implementation method. The second part is concerned with a particular problem in the mechanical system control: estimating velocity when the even rate from a digital encoder is lower than the controller's sample time. Methods are...

Evaluation of Caltrans District 10 Automated Warning System: Year Two Progress Report

MacCarley, Art
1999

District 10 of the California Department of Transportation (Caltrans) encompasses an area of seasonal fog and dust-related visibility problems that have been the cause of numerous multi-car traffic collisions, many fatal. In 1990, motivated by the expansion of State Route 120 (SR 120) connecting Interstate Highway 5 (I-5) and State Route 99 (SR 99), Caltrans proposed a sophisticated multi-sensor automated warning system as a means for reducing incidents in this high-traffic area. This proposal, and the significant development effort that followed, culminated in the implementation of Phase...

Adaptive Throttle Control For Speed Tracking

Xu, Z.
Ioannou, P.
1994

In this paper, the authors design an adaptive control scheme for electronic throttle that achieves good tracking of arbitrary constant speed commands in the presence of unknown disturbances. The design is based on a simplified linear vehicle model which is derived from a validated nonlinear one. The designed control scheme is simulated using the validated full order nonlinear vehicle model and tested on an actual vehicle. The simulation and vehicle test results are included in this paper to show the performance of the controller. Due to the learning capability of the adaptive control...

Effects of Cooperative Adaptive Cruise Control on Traffic Flow: Testing Drivers' Choices of Following Distances

Shladover, Steven E.
Nowakowski, Christopher
Cody, Delphine
Bu, Fanping
O’Connell, Jessica
Spring, John
Dickey, Susan
Nelson, David
2009

A Cooperative Adaptive Cruise Control (CACC) system has been developed by adding a wireless vehicle-vehicle communication system and new control logic to an existing commercially available adaptive cruise control (ACC) system. The CACC is intended to enhance the vehicle-following capabilities of ACC so that drivers will be comfortable using it at shorter vehicle-following gaps than ACC. If this is shown to be the case, it offers a significant opportunity to increase traffic flow density and efficiency without compromising safety or expanding roadway infrastructure.This report describes the...

Intelligent Cruise Control Systems And Traffic Flow Stability

Darbha, Swaroop
Rajagopal, K.r.
1998

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...

Effectiveness of Adaptive Traffic Control for Arterial Signal Management: Modeling Results

Skabardonis, Alexander
Gomes, Gabriel
2010

This study identifies and selects the most promising existing adaptive control algorithms for arterial streets, evaluates performance through simulation, and develops a plan for field testing of the most promising algorithms on a real-world arterial. A section of Highway 1 in the city of Lomita, California was selected as the test site for evaluation of adaptive signal control strategies. A methodology was developed to obtain a time-varying origin-destination (OD) matrix from the system loop detector data at the test site. The calibrated OD matrix was applied to a microscopic...

Development of Requirement Specifications for Transit Frontal Collision Warning System

Wang, Xiqin
Chang, Joanne
Chan, Ching-Yao
Johnston, Scott
Zhou, Kun
Steinfeld, Aaron
Hanson, Matt
Zhang, Wei-Bin
2004

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...

A Machine Vision Based System for Guiding Lane-change Maneuvers

Malik, Jitendra
Koller, Dieter
Luong, Tuan
1995

We propose a new approach for vision based longitudinal and lateral ve-hicle control which makes extensive use of binocular stereopsis. Longitudi-nal control - i.e. maintaining a safe, constant distance from the vehicle infront - is supported by detecting and measuring the distances to leadingvehicles using binocular stereo.A known camera geometry with respect tothe locally planar road is used to map the images of the road plane in thetwo camera views into alignment.Any significant residual image disparitythen indicates an object not lying in the road plane and hence a potentialobstacle....

Relieve Congestion and Conflicts Between Railroad and Light Rail Grade-Crossing Intersections

Zhang, Wei-Bin
Li, Meng
Wu, Guoyuan
Zhou, Kun
Bu, Fanping
2010

This report specifically summarizes the work that the PATH team has performed at this stage of Task Order 6407 in continuation of previous Task Order 5407. We have conducted an in-depth study of problems associated with grade crossingsfor this project.We started from the system design based on the proposed adaptive trolley signal priority (ATSP) system. The system is designed for large-scale field implementation of the ATSP system. It consists of three sub-systems: onboard sub-system, roadside control sub-system and central control sub-system. The system input and output diagram is based...

A Functional Architecture For Automated Highway Traffic Planning

Tsao, H. S. Jacob
1994

This report defines an architecture for Automated Highway System (AHS) capacity-optimizing traffic planning functions. It identifies major traffic planning functions useful for optimizing the capacity of one or more major AHS operating scenarios and organizes them in a robust architecture that is modular, hierarchical, complete, expandable and integratable.