PATH

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...

Driving Intelligence Replacement in a Decision-Oriented Deployment Framework for Driving Automation

Tsao, H.-S. Jacob
Ran, Bin
1996

What some human drivers have done wrong has been blamed for much of the problem associated with the current highway systems. For example, driver inattention, fatigue and other human errors have often been cited as major sources of safety hazard on current highways and human capabilities as major limitations on current highway capacity. Such human deficiencies and the pervasive urban traffic congestion have motivated the concept of Automated Highway Systems (AHS). The fundamental objective of AHS is to achieve user and societal benefits through replacing human driving by automated machine...

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...

Steady State Conditions on Automated Highways

del Castillo, Jose M.
Lovell, David J.
Daganzo, Carlos F.
1995

This paper is concerned with technical investigations of traffic operations on automated highways. Estimates are made of the steady-state capacity of such freeways, paying particular attention to the effect of entry and exit maneuvers. The possibility of scheduling departing vehicles appropriately into platoons to minimize extraneous maneuvers is investigated. Characteristics of urban areas likely to be candidates for automated freeways are discussed, and some shortcomings of automated freeways, vis-à-vis conventional freeways, are pointed out. Finally, some areas of future research needs...

Experimental Studies on High Speed Vehicle Steering Control with Magnetic Marker Referencing System

Tan, Han-Shue
Bougler, Bndicte
2000

This project is a one-and-half year research and experimental effort that builds on the results of as well as supplements the efforts in MOU 250, "Experimental Studies on Vehicle Control Systems." It focuses on an emerging issue of the high-speed steering control: how to conduct robust automatic vehicle steering control at highway speed based on a look-down lateral sensing system.