Traffic Operations and Management

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.

Section-Related Measures of Traffic System Performance: Prototype Field Implementation

Ritchie, Stephen G.
Sun, Carlos
Oh, Seri
Oh, Cheol
2001

In this project (MOU 336),an initial phase of a field implementation was accomplished of the results of a previous research project (MOU 224),in which a vehicle reidentification algorithm based on loop signature analysis was developed using freeway traffic data.This algorithm was extended to non-freeway cases, initially using a section of 2-lane major arterial in cooperation with the City of Irvine,California.The technique was enhanced to address problems such as "irregularities " in vehicle signatures associated with trucks,tail-gating vehicles and erroneous counting of vehicles,with the...

Some Theoretical Aspects Of The Benefits Of En-route Vehicle Guidance (ervg)

Al-Deek, Haitham M.
Kanafani, Adib K.
1989

This paper concerns the benefits from vehicle route guidance in urban networks. We suppose that vehicle routes can be altered by En-Route Vehicle Guidance (ERVG) in such a way as to achieve system optimal assignment. Benefits are measured by the savings in total travel time for a given demand when comparing this assignment with the user equilibrium, which is assumed to occur in the absence of route guidance. A continuum approach is used to analyze some idealized corridors in which a freeway is superimposed over a dense grid of surface streets. Two cases are considered: in the first, the...

Enhanced AHS Safety Through the Integration of Vehicle Control and Communication

Hedrick, J. K.
Uchanski, M.
Xu, Q.
2003

In fiscal year 2002/2003 we finished the study of the effect of vehicle-vehicle/vehicle-roadside communication on the performance of adaptive cruise control (ACC) systems. Two simulation studies were finished. The first is a single ACC vehicle simulation using MATLAB/SIMULINK. A cut-in scenario and a braking scenario are tested. Communication greatly saves control effort in the former scenario, while it has little effect in the latter. The other work simulates ACC controlled highway merging using SHIFT language. The results show the beneficial effects of communication in terms of the...

The Cell Transmission Model. Part I: A Simple Dynamic Representation Of Highway Traffic

Daganzo, Carlos
1993

This paper presents a simple representation of traffic on a highway with a single entrance and exit. The representation can be used to predict traffic's evolution over time and space, including transient phenomena such as the building, propagation and dissipation of queues. The easy-to-solve difference equations used to predict traffic's evolution are shown to be the discrete analog of the differential equations arising from a special case of the hydrodynamic model of traffic flow. The proposed method automatically generates appropriate changes in density at locations where the...