PATH

Empirical Comparison of Travel Time Estimation Methods

Zhang, Xiaoyan
Rice, John
Bickel, Peter
1999

In this paper, we conduct an empirical comparison of travel time estimation methods based on single-loop detector data. The methods of concern are the regression method based on an intuitive stochastic model as proposed by Petty et al. in [7], and the conventional method of using an identity relating speed, flow and occupancy with the assumption of a common vehicle length. The analysis is tailored to fit in the limitations imposed by available field data sets. We also introduce several variations of the regression method and give examples which suggest directions for future work to further...

Demonstration of Automated Heavy-Duty Vehicles

Shladover, Steve E.
Lu, Xiao-Yun
Song, Bongsob
Dickey, Susan
Nowakowski, Christopher
Howell, Adam
Bu, Fanping
Marco, David
Tan, Han-Shue
Nelson, David
2006

This project was created in order to continue progress toward a future in which vehicle automation technologies are able to improve transportation operations. In the wake of the termination of the National Automated Highway Systems Consortium (NAHSC) program in 1998, the California Department of Transportation (Caltrans) created The Phoenix Project to bring together the organizations that remained interested in this future vision. The discussions within The Phoenix Project focused on the opportunities that could be gained from earlier deployment of automation technologies on transit buses...

Address Resolution in One Lane Automated Highway Systems

Bana, Soheila V.
Varaiya, Pravin
1999

Address Resolution Protocols (ARP) are used in Automated Highway Systems (AHS) to establish communication among vehicles. The purpose of the ARP is to determine the network address of neighboring vehicles. We are proposing an innovative solution that takes advantage of the automated road infrastructure. For providing addresses initially and uses the communication network itself for updating the network communication addresses in a one lane automated highway system. The protocol has been modeled using PROMELA [1], and simulated and verified by SPIN [2]. SPIN is a tool for analyzing the...

Aerodynamic Forces on Truck Models, Including Two Trucks in Tandem

Hammache, Mustapha
Michaelian, Mark
Browand, Fred
2001

The present wind tunnel experiment describes 6-component force and moment data measured for both the cab and the trailer of a simplified model truck. Forces and moments are presented in coefficient form. The cab is sufficiently smooth that no flow separation occurs at zero yaw. The trailer has rounded forward vertical edges and sharp upper and lower edges. Both cab and trailer have wheels. The test matrix includes variation of the cab-trailer gap, and the yaw angle between the model plane of symmetry and the axis of the wind tunnel. The yaw angle is meant to account for the presence of an...

Freeway Performance Measurement System (PeMS)

Chen, Chao
2003

The freeway Performance Measurement System (PeMS) collects real time traffic data from sensors and generates performance measures of vehicle miles traveled, hours traveled, and travel time. This project is sponsored by the California Department of Transportation (Caltrans). PeMS provides tools and reports for traffic planners, operators, and engineers. It has a Web interface. Growing traffic demand in metropolitan areas has far outpaced increases in freeway lane-miles in the United States. The solution to congestion lies in increasing the efficiency of existing infrastructure. Performance...

Evaluation of Portable Automated Data Collection Technologies: Interim Report, Work Accomplished During Fiscal Year 2005-2006

Banks, James H.
2006

This report documents work accomplished during Fiscal Year 2005-2006 as a part of a research project entitled “Evaluation of Portable Automated Data Collection Technologies.” Major activities during this period included a literature survey, surveys of potential users and vendors, preliminary evaluation of portable data collection technologies to select candidate systems for demonstration, and development of demonstration plans. There is demand for portable automated data collection systems for uses related to planning, traffic operations, traffic census, and traffic surveillance functions...

Field Experiments Demonstrate Fuel Savings for Close-Following

Michaelian, Mark
Browand, Fred
2000

There are only two ways to increase the throughput of vehicles on a highway—either construct more freeway lanes, or accommodate a shortened average spacing between individual vehicles (while maintaining speed). Providing a rational means for close-following is an attempt to accomplish the latter. The maximum throughput for a typical freeway lane is about 2000 vehicles/hour, and is roughly independent of the attributes of any particular freeway. The number is remarkably inelastic varying little over the past twenty years in spite of great improvements in the design of freeways and in the...

New Approach to Bottleneck Capacity Analysis: Final Report

Banks, James H.
2006

A capacity analysis approach intended as an alternative to the traditional Highway Capacity Manual (HCM) method was evaluated. One- and two-stage models of pre-queue and queue discharge flow (each of which might be thought of as representing “capacity” in some sense) were developed and compared with one another and the HCM method. Two-stage models related capacity flows to intervening variables, including average time gaps (average time separations between the rear of a vehicle and the front of one following it) in the critical lane (that with the highest flow rate) and the critical lane...

Transient Aerodynamic Effects on a Four-Car Platoon During Passing Maneuvers: Data Summary

Tsuei, L.
Hedrick, J. K.
Savas, O.
1999

In order to provide reliable control algorithms on PATH automated highway system, knowledge of the transient aerodynamic forces is important from the point of the controlla- bility of the platoon and individual vehicles. In a passing maneuver, the platoon members may experience severe aerodynamic forces and yaw moment when another vehicle overtakes. Similar phenomenon can be seen in our daily life as one car passes the other but much more complicated flow field is expected when the interaction involves in a multi-vehicle platoon. It is the purpose of this study to quantify the unsteady...

Safety Performance and Robustness of Heavy Vehicle AVCS

Taylor, R. Jemonde
Yih, Paul
Gerdes, J. Christen
2005

Dynamically, heavy trucks are inherently different than passenger cars. In addition to the increase rollover risk arising from an elevated center of gravity height, heavy trucks possess additional failure modes such as jackknifing and excessive trailer swing. As a response to these issues, significant research has been performed in the last three decades to establish safety metrics for heavy trucks based on dynamic testing. This research has had an impact on determining acceptable size and weight restrictions for heavy vehicles and on the actual design of heavy trucks for increased safety...