Roads/Highways

Freeway Safety as a Function of Traffic Flow: The FITS Tool for Evaluating ATMS Operations

Golob, Thomas F.
Recker, Wilfred W.
Alvarez, Veronica
2002

Understanding the benefits of improved traffic flow (reduced congestion) is critical to the assessment of investments in infrastructure or traffic management and control. Improved flow should lead to reductions in travel time, vehicle emissions, fuel usage, psychological stress on drivers, and improved safety. However, the manner in which safety is improved by smoothing traffic flow is not well understood. The documented research is aimed at shedding light on the complex relationships between traffic flow and traffic accidents (crashes).

Vehicle To Roadside Communications Study

Polydoros, Andreas
Dessouky, Khaled
Pereira, Jorge M. N.
Sun, Chung-ming
Lee, Kuo-chun
Papavassiliou, Thomas D.
Li, Victor O. K.
1993

The objective of this study is to address the communication system design issues of Intelligent Vehicle Highway Systems (IVHS). The focus of Phase I of this research is the design for California Advanced Driver Information Systems (CADIS). The emphasis is on the architecture and topology aspects of the physical link and access layers connecting the moving layers with the fixed infrastructure. The work is divided into the following categories: Automatic Vehicle Identification (AVI), IVHS communications survey and functional requirements, modeling of IVHS fading channels, multiple-access...

Determining the Effectiveness of HOV Lanes

May, Adolf D.
Leiman, Lannon
Billheimer, John
2007

This document is the final report for the two-year PATH Project “Determining the Effectiveness of HOV Lanes”. It has been supported by the California Department of Transportation (Caltrans). The primary objectives of this project have been to evaluate freeways having on-freeway HOV lanes in terms of vehicle-travel, person-travel, occupancy distribution, shape and duration of the peak period, congestion patterns, and air quality both in the HOV lane and the adjacent mixed-flow lanes.Based on a comprehensive literature review an extensive list of reference was developed, along with summaries...

Sensor-Friendly Freeways: Investigation of Progressive Roadway Changes to Facilitate Deployment of AHS

Misener, James A.
Griffiths, Paul
Johnson, Lee
Segal, Andy
2001

Intelligent "driver assistance" systems which utilize in-vehicle forward-looking sensors can be supplemented by vehicle-vehicle and vehicle-highway cooperative elements to comprise a "sensor-friendly" highway environment that would enhance the operational efficiency, and ultimately, the safety benefits of these systems. In our research, we have identified the current limitations of autonomous sensing systems in target/background discrimination with cluttered highways. Based upon this, and by limiting ourselves to "sensed" (and not wireless) systems, we have conceived relatively inexpensive...

Real-time Density Estimation on Freeway with Loop Detector and Probe Data

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

Density, speed and flow are the three critical parameters for traffic analysis. Traffic management and control with high performance require accurate estimation/prediction of distance mean speed and density for large spatial and temporal coverage. Speed, including time mean speed and distance mean speed, and flow estimation are relatively easy to be measured and estimated in the practical site, but accurate density estimation is very difficult. Inductive loop detector systems have been widely deployed, it makes better sense to fully adopt available infrastructure to achieve required...

Models, Simulation, And Performance Of Fully Automated Highways

Varaiya, Pravin
1994

The research findings presented in this report deal with the modeling, simulation and performance evaluation of fully automated highway systems ( AHS). The report begins with a brief reconstruction of the history of the AHS concept, and a particular AHS proposal that has been intensely studied in PATH. The next section summarizes the principal findings of AHS performance. This is followed by an overview of the simulation program SmartPath. An outline of the current work on SmartPath and plans for the immediate future are given. This section also proposes an object oriented distributed...

Implementation and Evaluation of Automated Vehicle Occupancy Verification

Chan, Ching-Yao
Bu, Fanping
Singa, Krute
Wang, Huili
2011

Vehicle occupancy verification is a principal impediment to more efficient HOV/HOT lane enforcement. However, no automated solution has yet been developed for permanent field implementation. Given widespread plans for development of HOV and HOT lanes in a number of metropolitan areas, improved vehicle occupancy verification techniques urgently need to be explored as well as the legal and institutional barriers to their implementation.A research project to evaluate the technologies for vehicle occupancy verification was conducted by California PATH of University of California at Berkeley....

The Prospects for High Occupancy/Toll (HOT) Lanes: Where Should They Be Implemented

Dahlgren, Joy
2001

There is increasing interest in building new high occupancy toll (HOT) lanes and in converting high occupancy vehicle (HOV) lanes with unused capacity to HOT lanes. Like HOV lanes, HOT lanes provide an incentive for travelers to use HOVs, but unlike HOV lanes, they can always be well utilized by varying the toll over the congested period, thus providing more congestion relief than an HOV lane with unused capacity. This report provides guidelines regarding the circumstances in which HOT, HOV, and mixed flow lanes are most appropriate. Using a queueing model combined with a mode choice model...

Safetrip-21: Connected Traveler

Sengupta, Raja
Misener, Jim
Ahern, Katherine
Chan, Ching-Yao
Gupta, Somak Datta
Jariyasunant, Jerry
Li, Jing-Quan
Long, Christopher
Mai, Eric
Manasseh, Christian
Nowakowski, Christopher
O’Connell, Jessica
Rezai, Shahram
Steelhorst, Michael
Zhang, Liping
Zhang, Wei-Bin
Zhou, Kun
Zhou, Xeusong
2010

The US DOT RITA Volpe Center entered into a cooperative agreement with the California Department of Transportation (Caltrans) to establish the inaugural SafeTrip 21 field test site in the San Francisco Bay area [named Connected Traveler]. Specifically, the site encompasses I-880 from Oakland to San Jose on the east bay and from San Jose to just south of the San Francisco International Airport, along U.S. 101 and California State Route (SR) 82. The site includes the SR-84 Dumbarton Bridge toll crossing, which links I-880 and U.S. 101. Caltrans's partners include the Metropolitan...

Causes of Freeway Productivity Decline and the Opportunities for Gain: A Quantitative Study

Varaiya, Pravin
2008

Work done under TO 5306 led to three accomplistments. First, a measure of freeway productivity was proposed. Second, the causes of productivity decline led to the notion of "congestion pie." Both productivity loss and congestion pie are available at PeMS applications. Third, the study entitled "An Empirical Assessment of Traffic Operations" [1] provides a detailed empirical account of congestion.