PATH

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...

Improving Operations Using Advanced Surveillance Metrics and Existing Traffic Detectors

Coifman, Benjamin
Varaiya, Pravin
2002

1 OVERVIEW Because travel time provides information over an extended freeway link, rather than at a single point, it is a key parameter for ATIS applications and it is a powerful tool for ATMS. Under PATH sponsorship, we have already developed a prototype travel time measurement system that utilizes existing dual loop speed traps and "model 170" controllers. This research has advanced the work by improving the vehicle reidentification algorithms (Sections 2 and 3) and applying the travel time measurement system over seven freeway links in real-time (Section 4). This latter work was...

Evaluation of Wet Weather Accident Causation Criteria

Oh, Soon Mi, MS
Ragland, David R., PhD
Chan, Ching-Yao, PhD
2010

This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP).The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the notable...

Intelligent Diagnosis Based On Validated And Fused Data For Relilability And Safety Enhancement Of Automated Vehicles In An IVHS

Agogino, Alice
Chao, Susan
Goebel, Kai
Alag, Satnam
Cammon, Bradly
Wang, Jiangxin
1998

Vehicles in an IVHS system rely heavily on information obtained from sensors. So far, most control systems make the implicit assumption that sensor information is always correct. However, in reality, sensor information is always corrupted to some degree by noise which varies with operating conditions, environmental conditions, and other factors. In addition, sensors can fail due to a variety of reasons. To overcome these shortcomings, sensor validation is needed to assess the integrity of the sensor information and adjust or correct as appropriate. In the presence of redundant information...

A System Review of Magnetic Sensing System for Ground Vehicle Control and Guidance

Chan, Ching-yao
2002

This report contains research results of studies on magnetic marker systems that are used as a posi-tionreference system for Advanced Vehicle Control and Safety Systems. Effects of external objectsand earth background fields on such systems are investigated with experimental measurements inPart I. The results show that signal processing techniques must be adopted in field applications toimprove the accuracy and robustness of sensing algorithms. Part II of the report contains experimen-talresults from an evaluation study of PATH marker system and 3M Tape system. The objective isto identify...

Clean Hydrogen for Transportation Applications: Report

Miller, Marshall, PhD
Weinert, Jonathan
Nicholas, Michael
2006

The California Department of Transportation, as part of their involvement in the California Hydrogen Highway initiative, is planning to construct a hydrogen station at their new maintenance facility in Sylmar, CA (Shop 7, at the junction of I-5 and I-405). This report was written to provide Caltrans information on the design and cost of various hydrogen station types. This information will be used to guide decision-making in choosing the station type and size to meet the anticipated hydrogen vehicle demand at their new facility.

Evaluation of Truck and Bus Automation Scenarios: Operations Cost Analysis

Botha, Jan
Day, Jennifer E.
Adibhatla, Nagabhargavi
2004

Automated bus and truck systems hold the potential to improve road safety by eliminating some human error, increase the vehicle throughput by allowing vehicle convoying to shorten headways, and reduce costs associated with infrastructure, user time, and drivers. In this study, an automated bus system (ABUS) was compared with more-conventional light rail and bus-on-dedicated-lane (BDL) alternatives. A cost comparison (excluding accident costs) was also made among an automated freight trucking system (AHS-Truck), a no-build base condition, and configurations involving the addition of a...

Coordinating Automated Vehicles via Communication

Bana, Soheila Vahdati
2001

This dissertation addresses the coordination of automated vehicles in an Auto- mated Highway System (AHS). Tra c in an AHS is organized as tightly spaced platoons to increase road capacity and safety. Vehicles in AHS are automated and their safe interaction is the subject of this research. This dissertation discusses issues in the design and imple- mentation of a controller for automated vehicles that coordinates the interaction between vehicles. We rst de ne a formalism for safe interaction of automated vehicles and then design a controller algorithm for an individual vehicle that...

Assessing the Benefits and Costs of ITS Projects: Volume 2 An Application to Electronic Toll Collection

Gillen, David
Li, Jianling
Dahlgren, Joy
Chang, Elva
1999

The Carquinez Bridge ETC project is a pilot project of a statewide toll bridge improvement project undertaken by Caltrans. Caltrans owns and operates nine toll bridges statewide. Over the last five years, traffic on all area bridges has increased from 129 million vehicle crossings in Fiscal year (FY) 1992-93 to 140 million in FY 1996-97, with an average annual rate of 2 percent as indicated in Figure 1. However, the toll facilities are antiquated. The bridges use a toll collection system known as Toll Registration, Audit and Collection (TRAC) installed in the early 1980s, and tolls have...