Traffic Operations and Management

User Perceived Benefits with Navigation Systems

Commeignes, Hervé
1991

It has often been assumed that travel time savings are only beneficial to the users of route guidance and navigation systems. In particular, absolute travel time savings have been emphasized, but there has been little interest in relative time savings between equipped and unequipped vehicles. Part 2 of this report investigates to what extent relative travel time savings decrease as the percentage of equipped vehicles increases.In order to compensate for a possible decrease in relative time savings, some other potential services that can be provided by navigation systems are identified in...

California Transportation Management Centers Part 1. Assessment Of Existing Capabilities

Lo, Hong K.
Hall, Randolph W.
Windover, John R.
1993

Transportation Management Centers (TMCs) are focal points for monitoring and operating traffic management systems. As new technologies are developed through research in Intelligent-Vehicle- Highway Systems (IVHS), these TMCs will assume increasingly more importance as command and control centers for transportation operations. This study is aimed at developing visions for how the TMC of the future will exploit the capabilities of IVHS. Part 1 of this study, reported herein, is an assessment of existing TMC capabilities in the State of California. Part 2, to be reported later, will develop...

Relationships Among Urban Freeway Accidents, Traffic Flow, Weather and Lighting Conditions

Golob, Thomas F.
Recker, Wilfred W.
2001

Linear and nonlinear multivariate statistical analyses are applied to determine how the types of accidents that occur on heavily used freeways in Southern California are related to both the flow of traffic and weather and ambient lighting conditions. Traffic flow is measured in terms of time series of 30-second observations from inductive loop detectors in the vicinity of the accident prior to the time of its occurrence. Results indicate that the type of collision is strongly related to median traffic speed and to temporal variations in speed in the left and interior lanes. Hit-object...

The Design of a Controller for a Following Vehicle in an Emergency Lane Change Maneuver

Swaroop, D.
Yoon, Seok Min
1999

A lane change maneuver is one of the many appropriate responses to an emergency situation. The design of an Emergency Lane Change (ELC) maneu- ver for a platoon of two vehicles is considered in this paper. In response to the presence of a stationary or a slowly moving obstacle in the lane or any such emergency, the lead vehicle in the platoon designs an ELC trajectory on-line and broadcasts the trajectory curvature information in real time to its follower. The problem considered, in this paper, is the design of an integrated lateral and longitudinal controller that enables the follower to...

Safety Aspects of Freeway Weaving Sections

Golob, Thomas F.
Recker, Wilfred W.
Alvarez, Veronica M.
2003

One source of vehicle conflict is the freeway weaving section, where a merge and diverge in close proximity require vehicles either entering or exiting the freeway to execute one or more lane changes. Using accident data for a portion of Southern California, we examined accidents that occurred on three types of weaving sections defined in traffic engineering: Type A, where every merging or diverging vehicle must execute one lane change, Type B, where either merging or diverging can be done without changing lanes, and Type C, where one maneuver requires at least two lane changes. We found...

The Effects of Data Inaccuracy on the Performance of Traffic Signal Timing Plans

Lin, Wei-Hua
Liao, Lawrence C.
1998

This paper explores the performance of signal timing plans calibrated with perfect or imperfect information. The arrival information considered include arrival rates and arrival distributions. The study is conducted for different levels of arrival rates and different forms of arrival distributions under a wide range of arrival information inaccuracy, traffic intensity, and intersections with balanced and unbalanced flows.Our results indicate that the increase in delay, the number of stops, and queue length is in general insignificant when the arrival distribution used to calibrate the...

Path ATMIS/Systems State of the Research: Annual Report Fiscal Year 1997/1998

Tam, Robert
1998

This report presents a summary of California PATH Advanced Traffic Management and Traffic Information Systems (ATMIS) and Systems research for FY 1997-1998. For each project, a brief description is given of the objectives, status outline, and principal results. The report is organized into the following research topics: Surveillance Systems, Traffic Management Systems, Traffic Modeling, Traveler Information Systems, Public Transportation Systems, and System Integration and Benefit/Cost Analysis.

A Tool to Evaluate the Safety Effects of Changes in Freeway Traffic Flow

Golob, Thomas F.
Recker, Wilfred W.
Alvarez, Veronica M.
2003

This research involves the development of a tool that can be used to assess the changes in traffic safety tendencies that result from changes in traffic flow. The tool uses data from single inductive loop detectors, converting 30-second observations of volume and occupancy for multiple freeway lanes into traffic flow regimes. Each regime has a specific pattern of crash types, which were determined through nonlinear multivariate analyses of over 1,000 crashes on freeways in Southern California. These analyses revealed ways in which differences in variances in speeds and volumes across lanes...

Evaluation of On-ramp Control Algorithms

Zhang, Michael
Kim, Taewan
Nie, Xiaojian
Jin, Wenlong
Chu, Lianyu
Recker, Will
2001

The control of a traffic corridor, which consists of two major component - freeway system control and arterial street system control, aims to improve flows on both freeway and arterial streets, and has been demonstrated as an effective means to increase the level of service of a corridor system during peak periods. Ramp metering, or ramp control, has been considered to be a very important component of corridor traffic control. Ramp metering is the application of control devices such as metering signals to limit the number of vehicles entering a freeway. The fundamental philosophy of ramp...

Commuter Response To Traffic Information On An Incident

Koo, Ronald
Yim, Youngbin
1998

This paper presents and discusses how traffic information is obtained and how it affects travel behavior when a major freeway is congested. Immediately following a major highway incident south of San Francisco which caused congestion, a telephone survey was conducted of commuters who utilize the affected corridor of highway. The behavior of commuters before and during their commute at the time of the incident was determined, including obtaining traffic information and how the information influenced changes in route, mode of travel and departure time. The results of the survey suggest that...