PATH

A Comparative Safety Study of Limited versus Continuous Access High Occupancy Vehicle (HOV) Facilities

Jang, Kitae, MS
Ragland, David R., PhD
Chan, Ching-Yao, PhD
2009

The report summarizes the findings from comparative studies of safety performance between two different types of High Occupancy Vehicle (HOV) facilities in California - continuous access versus limited access. The findings show that HOV facilities with limited access offer no safety advantages over those with continuous access, whether measured by percentage of collisions, collisions per mile, collisions per VMT, or collision severity. As part of the present research, the authors investigated the relationship between HOV design features and safety performance of HOV facilities. One key...

Improving the Traffic Census and Highway Performance Monitoring System (HPMS) Programs

Mauch, Michael, PhD
Skabardonis, Alex, PhD
2020

The objective of this research study was to support the Traffic Census and Highway Performance Monitoring System (HPMS) Programs in identifying locations for motorized traffic data collection on public roads in California. The study analyzed the traffic census count locations for each District to determine at which Census count locations the automated and continuously collected Caltrans Performance Measurement System (PeMS) data could be used in lieu of manual traffic counts. Next, this research identified and evaluated count locations for motorized traffic data collection on non-State...

Why Its Projects Should Be Small, Local And Private

Weissenberger, Stein
1998

In this paper, the author contends that in order to produce and capture useful knowledge, early Intelligent Transportation Systems (ITS) projects should be local, small, and focused on realistic goals. The importance of cooperative networks that support knowledge acquisition and diffusion is stressed. Additionally, the author promotes the usage of private industry, especially to perform tasks for which they are best qualified.

Analysis, Design And Evaluation Of Avcs For Heavy-duty Vehicles

Yanakiev, Diana
Kanellakopoulos, Ioannis
1996

In this report, the authors develop two new nonlinear spacing policies, variable time headway and variable separation error gain, designed to all but eliminate the undesirable side effect of large steady-state intervehicle spacings. This disadvantage is pronounced in heavy-duty vehicles, which require larger time headways due to their low actuation-to- weight ratio. The first policy significantly reduces the transient errors and allows for the use of much smaller spacings in autonomous platoon operation, while the second one results in smoother and more robust longitudinal control.

Integration Of Fault Detection And Indentification Into A Fault Tolerant Automated Highway System

Douglas, Randal K.
Chung, Walter H.
Malladi, Durga P.
Chen, Robert H.
Speyer, Jason L.
Mingori, D. Lewis
1997

This work focuses on vehicle fault detection and identification. It also describes a vehicle health management approach based on analytic redundancy. It describes a point design of fault detection filters and parity equations that are developed for the vehicle longitudinal mode. A preliminary design of a range sensor fault monitoring system is outlined as an application of a new decentralized fault detection filter. This system combines dynamic state information already generated by the existing filter designs with inter-vehicle analytic redundancy

Vehicle Traction Control And its Applications

Kachroo, Pushkin
Tomizuka, Masayoshi
1994

This paper presents a study of vehicle traction control and discusses its importance in highway automation. A robust control strategy is designed for slip control, which in turn controls the traction. It is shown how traction control can be used to satisfy different objectives of vehicle control. The importance of traction is further emphasized by comparing its performance to passive controllers in a simulation study in which an impulse-like wind disturbance is introduced. The comparative study shows that the system under traction control is stable in the presence of external disturbances...

Event-based ATIS: Practical Implementation and Evaluation of Optimized Strategies

Jayakrishnan, R.
Tsai, Wei K.
Oh, Jun-Seok
Adler, Jeffrey
2001

This project further adapt and enhance the previous research of relevance to event-based Advanced Traveler Information Systems (ATIS) and implement the algorithms for traffic management in Anaheim. This study is also answering some basic questions in ATIS implementation associated with routing strategies, driver’s compliance and network performance. This research develops algorithms for static and dynamic optimal Changeable Message Signs (CMS). The optimized CMS schemes are based on performance evaluations using a traffic simulation-based evaluation model, DYNASMART (Dynamic Network...

Integrating a Comprehensive Modal Emissions Model into ATMIS Transportation Modeling Frameworks

Barth, Matthew
Malcom, Carrie
Scora, George
2001

Intelligent Transportation Systems (ITS) have generated considerable enthusiasm in the transportation community as a potential means to improve roadway safety, reduce congestion, enhance the mobility of people and goods, and reduce energy consumption and vehicle emissions. In order to estimate these potential benefits, new and improved analytical techniques and simulation models are being developed for ITS. In terms of environmental effects, the University of California, Riverside, College of Engineering-Center for Environmental Research and Technology (CE-CERT) has developed a...

SmartAHS and SHIFT Enhancements, Persistence and Query Interpretation

Misener, Jim
2000

We have enhanced and "tuned" SmartAHS and SHIFT to address a wide variety of functional and user needs. SmartAHS has become an important microsimulation tool for design, analysis and evaluation of AHS - and "pre-AHS" or AHS deployment - concepts and scenarios in dimensions of system performance (i.e., throughput and travel time), safety and comfort. The SmartAHS/Hybrid Systems Tools Interface Format (SHIFT) is the basis for SmartAHS, and it is the general hybrid systems simulator for user-defined AHS architectures.

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

Golob, Thomas F.
Recker, Wilfred W.
2003

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 both to the flow of traffic and to 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...