Traffic Operations and Management

Empirical Analysis of Traffic Breakdown Probability Distribution with Respect to Speed and Occupancy

Chow, Andy H.F.
Lu, Xiao-Yun
Qiu, Tony Z.
2009

From an operation viewpoint, traffic breakdown (from free-flow) was defined as when the average speed of traffic drops below a certain threshold. It is known that traffic breakdown is a stochastic phenomenon which can happen even when the traffic flow is below the capacity. The capacity has many definitions, such as that in HCM or the average of maximum daily flow. This study investigates the probability of breakdown at certain locations of freeway. The motivation is to find a practical capacity for each freeway section for active traffic control/operation purposes, which could be...

Alternative Traffic Signal Illumination

Cohn, Theodore E.
Greenhouse, Daniel
Knowles, Richard
1998

New technologies have enabled the production of traffic signals that have significant advantages over standard incandescent signals, including greater energy efficiency and lower maintenance costs. Before the new signals are installed in the field, it is important to assure that they as visible as the older signals. We have developed a quality index we term the usability factor (UF) which can be used to evaluate the visibility of a new device relative to that of a standard reference lamp. We have measured UF's of a variety of new types of lamps by means of heterochromatic flicker...

Extracting More Information from the Existing Freeway Traffic Monitoring Infrastructure

Coifman, Benjamin
2006

This report presents the results of TO 5302, Extracting More Information from the Existing Freeway Traffic Monitoring Infrastructure. This report represents significant advances in the PATH sponsored research into vehicle reidentification from conventional loop detectors, first by extending the methodology across major merge and diverge freeway sections. Second, it extends the methodology to single loop detectors. The report also extends the understanding of traffic phenomena impacting both traffic flow and the performance of the reidentification algorithms. It examines the impacts of lane...

Hybrid Data Implementation: Final Report for Task Number 3643

Khan, Sakib Mahmud, PhD
Fournier, Nicholas, PhD
Mauch, Michael, PhD
Patire, Anthony D, PhD
Skabardonis, Alex, PhD
2020

This report investigates how Caltrans may incorporate third-party vendor data into its established system for performance measurement to improve accuracy of vehicle hours of delay (VHD) estimates and to enable smarter deployment of point-based sensors, such as loops. Methods are evaluated to project data from multiple sources, including multiple vendors and internal data feeds, onto the same domain of analysis so as to compute performance metrics with high fidelity. The recommended VHD estimation method depends on the infrastructure type and the data available. Overall a hybrid approach...

Using Cooperative Adaptive Cruise Control (CACC) to Form High-Performance Vehicle Streams:Simulation Results Analysis

Liu, Hao
Kan, Xingan (David)
Shladover, Steven E.
Lu, Xiao-Yun
2018

This document contains detailed simulation results analysis and discussion for the Federal Highway Administration (FHWA) Exploratory Advanced Research (EAR) project entitled Using Cooperative Adaptive Cruise Control (CACC) to Form High-Performance Vehicle Streams. The objective of this study is to obtain authoritative predictions of traffic impacts of ACC and CACC at various market penetrations and define the CACC operation strategies that create the most capacity and throughput improvement in the freeway traffic stream. A microscopic traffic simulation environment has been developed for...

Enhancements To A Simulation Framework For Analyzing Urban Traffic Networks With Atis/atms

Jayakrishnan, R.
Rathi, U.
Rindt, C.
Vaideeshwaran, G.
1996

This report focuses on the DYNASMART simulation program presents a model that is capable of simulating large urban networks under various Advanced Traffic Management Systems (ATMS) and Advanced Traveler Information Systems (ATIS) strategies. It includes modules for driver responses to information and for capturing the dynamics of the network paths. The research also included the simulation study of a network in Orange County, California, where the benefits from candidate ATIS and ATMS strategies were evaluated. The DYNASMART model has evolved into a flexible tool that can be applied to...

Spatial and Temporal Utility Modeling to Increase Transit Ridership

Church, Richard L.
Noronha, Val
Lei, Ting
Corrigan, Wils
Burbidge, Shaunna
Marston, Jim
2005

The objective of this research project was to develop a better understanding of the possible alternatives that a large employment center, like the University of California at Santa Barbara, can adopt in order to better utilize transit, mitigate traffic, and reduce demand for on-site parking. Although this project was oriented to the UCSB campus, the techniques and approaches developed in this project were designed to be equally applicable elsewhere. There were three major elements of this project: 1) develop an understanding of commuting employees through the use of a survey, 2) identify...

Travel Times on Changeable Message Signs: Pilot Project

Chen, Chao
2004

We describe a system to display real time travel times on Changeable Message Signs (CMS) in California. CMS's show dynamic information and allow the Traffic Management Center (TMC) to communicate to drivers information about traffic diversion, incidents, and delays. This type of service is deployed in other parts of the country and world and has been shown to be useful. For this project, we implemented a system that uses existing algorithms for travel time estimation and prediction.

Effectiveness of VMS Using Empirical Loop Detector Data

Huo, Hong
Levinson, David
2006

This study employs traffic data and incident data from the Twin Cities of Minneapolis and St. Paul, Minnesota. The conclusion in this study provides guidance on making policy about investing in VMS systems.Few studies utilize empirical traffic data. They either use costly surveys or conduct traffic simulation, which are expensive and may not conform well to reality. This study uses empirical traffic flow and occupancy data on both mainline and ramps, collected every 30 seconds to estimate the effectiveness of VMS. The variation of diversion rate before and after warning messages is...

Feasibility Study Of Advanced Technology Hov Systems: Volume 1: Phased Implementation Of Longitudinal Control Systems

Chira-Chavala, Ted
Yoo, S. M.
1992

This study investigates issues concerning the implementation and impacts of lateral guidance/control systems and the phased implementation of these systems in exclusive-access High Occupancy Vehicle (HOV) lanes. The study is divided into 5 volumes. The objectives of each volume are as follows: Vol. 1: identify strategies for early deployment of longitudinal control technologies on the highway, and to evaluate potential impacts of these strategies on traffic operation, highway capacity, and traffic accidents. Vol. 2A: assess the feasibility of early deployment of Roadway Powered Electric...