Traffic Operations and Management

PATH ITS Research Digests

Chira-Chavala, Ted
2001

Ramp meters are commonly used to relieve congestion on freeways. What is the value of these systems? Ramp metering can alleviate recurrent, regular traffic congestion, such as that caused by the daily commute. The goal is usually to maintain uninterrupted freeway flow at a certain acceptable level, but it transfers delay to the entrance ramp, where excess demand is forced to wait. This report summarizes ramp metering technologies, reviews the algorithms commonly used with them, and uses a traffic simulation model to identify the benefits and costs of using these systems. We used a...

Database Environment for Fast Real-Time Simulation of Urban Traffic Networks with ATMIS

Jayakrishnan, R.
Sheu, Phillip
Wang, Taehyung
Xu, MinHua
2000

This project develops the environment for using the ATMIS simulation software developed under previous PATH projects (MOUs 39, 84, and 170) for real-time traffic simulation and scenario analysis with feedback from the real urban network. keywords: traffic simulation, databases, object-relation databases, dynasmart

Evaluation of Potential ITS Strategies Under Non-Recurrent Congestion Using Microscopic Simulation

Chu, Lianyu
Liu, Henry X.
Recker, Will
Hague, Steve
2003

This report presents a micro-simulation method to evaluate potential ITS applications. Based on the commercial PARAMICS model, a capability-enhanced PARAMICS simulation environment has been developed through integrating a number of plug- in modules implemented with Application Programming Interfaces (API). This enhanced PARAMICS simulation can thus have capabilities to model not only the target traffic conditions and operations but also various potential ITS strategies. An evaluation study on the effectiveness of potential ITS strategies under the incident scenarios is conducted over a...

"Study of Traffic at a Freeway Merge and Roles for Ramp Metering"

Cassidy, Michael J.
Rudjanakanoknad, Jittichai
2002

Traffic data measured near the junction of a single-lane on-ramp (with metered inflows) and a three-lane freeway were carefully studied for four days during the rush. The data showed the area around this merge junction became a bottleneck each day when the on-ramp's meter allowed its inflows to rise in the presence of high flows arriving from the freeway. Detailed study during these times further showed that queueing actually arose some distance downstream of the merge and that these queues were caused by drivers who, having just entered the freeway's shoulder lane from the on-ramp, slowed...

Median Light Rail Crossing: Accident Causation And Countermeasures

Coifman, Benjamin
Bertini, Robert L.
1997

This paper focuses on accident causation and countermeasures at arterial median light rail grade crossings. It synthesizes accident causation and prevention literature from several fields, including traffic engineering, human factors and cognitive psychology, as it relates to the complex LRT grade crossing.

Travinfo Evaluation: Institutional Element Phase 2 Results

Hall, R.
Loukakos, D.
Weissenberger, S.
Yim, Y. B.
1996

This report presents the results of year two of the institutional evaluation of the TravInfo Field Operational Test (FOT). Numerous core participants and committee members were interviewed. The second year was dominated by TravInfo implementation issues, chief among which were: resolution of public/private controversies in the design of TravInfo and the attempt to ensure the completion of Caltrans' Traffic Operations System (TOS) for meeting the TravInfo schedule. Based on the interviews, the TravInfo organization is viewed at having been effective in resolving these issues.

Data For Transportation Modeling In The Santa Monica Corridor

Dahlgren, Joy
1998

The City of Los Angeles and Caltrans would like a simulation testbed for testing alternate traffic management strategies in the Santa Monica corridor. This study assesses the data available for such a simulation and describes data needs, potential sources, and data preparation required. It presents a work plan and resource requirements for acquiring the necessary data. The Appendix analyzes the conditions under which a simulation testbed is worthwhile. This study supported another PATH project, Los Angeles Smart Corridor Simulation Feasibility Study (MOU 270), which analyzed candidate...

Impacts of Computer-Mediated Communication on Travel and Communication Patterns: The Davis Community Network Study

Balepur, Prashant Narayan
1998

This report examines the interactions among different forms of communication, where travel is also considered a form of communication. Data for this study comes from 148 respondents to the "Activity Diary" survey instrument of the Davis Community Network (DCN) project, which obtained information on 636 uses of DCN. Generation, elimination and modification were considered to be the three major potential results of the present DCN communication and the five major types of communication considered were: in-person, physical object, electronic, in-person with travel, and physical object with...

The Economics Of Traffic Information: A State-of-the-art Report

Malchow, M.
Kanafani, A.
Varaiya, P.
1996

This working paper is a preliminary review of the state of the art in the study of theeconomics of traffic information. The focus is on the different methods used to model thedecision process of drivers in a traffic system, and on the effect of traffic information on thisprocess. In addition, the review includes the characterization of information in terms of contentand accuracy. The purpose is to develop an understanding of the market for different types oftraffic information. The paper also includes some preliminary models that can be used to modelthe demand and supply of traffic...

On the Numerical Treatment of Moving Bottlenecks

Daganzo, Carlos
Laval, Jorge A.
2003

This report is part of PATH Task Order 4141 and shows how moving obstructions can be modeled numerically with kinematic wave theory. It shows that if a moving obstruction is replaced by a sequence of fixed obstructions at nearby locations with the same "capacity", then the error in vehicle number converges uniformly to zero as the maximum separation between the moving and fixed bottlenecks is reduced. This result implies that average flows, densities, accumulations and delays can be predicted as accurately as desired with this method. Thus, any convergent finite difference scheme can now...