Traffic Operations and Management

Evaluation of Traffic and Environment Effects on Skid Resistance and Safety Performance of Rubberized Open-grade Asphalt Concrete

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

Wet pavement-related collisions represent a significant traffic safety concern, due in part to the lack of adequate friction between tire and pavement, known as skid resistance. State agencies employ a skid number (SN) system, based on a standard test procedure in which a locked wheel is towed at 40 mph and the skid number (SN40) is calculated from the measured resistance. SN40 is used as a reference value for speeds both greater than and less than 40 mph. For most Departments of Transportation (DOTs) in the nation, excluding California, pavements for which the SN40 is below 30 are deemed...

Improving Mobility Through Enhanced Transit Services: Case Studies for Transit-Taxis

Widmann, Joshua H.
Miller, Mark A.
2006

This report, an interim deliverable for Task Orders 5408 and 6408: “Improving Mobility through Enhanced Transit Services”. Thus far in the study we have performed a review of the literature and conducted a small number of site-specific case studies for transit agencies in North America identified from the literature review as either currently having or in the past having had transit-taxi service implemented in their agency’s jurisdiction. We initially classified alternative concepts of transit-taxis into a typology of three service design options based on a review of the literature: 1)...

Dynamic Path-Based Equilibrium Assignment With Microscopic Traffic Simulation

Liu, Henry
Lianyu, Chu
Recker, Will
2005

This report summarizes research work conducted under TO4158 at the California ATMS Testbed of the Institute of Transportation Studies at the University of California, Irvine. Under this task order, the California ATMS testbed hosted two full-time PATH research postdocs (Henry Liu and Lianyu Chu) whose general responsibilities are focused on applications of ATMS in the Testbed environment. They are generally responsible for ensuring that the functional capabilities of the Testbed are designed, developed and maintained in a manner that complements and enhances the ATMS research objectives of...

Medium Access Control Protocol Design for Vehicle-Vehicle Safety Messages

Xu, Qing
Mak, Tony
Ko, Jeff
Sengupta, Raja
2005

We propose a Medium Access Control (MAC) protocol design for a vehicle to send safety messages to other vehicles. We develop a QoS model for safety messages consistent with the active safety systems literature. Each message has a range and useful lifetime. The QoS target is to have each message be received with high probability within its specified lifetime by each vehicle within its specified range. The protocol design is based on rapidly re-broadcasting each message multiple times within its lifetime in combination with the 802.11 DCF. This makes the design compatible with the emerging...

Driver/Pedestrian Behavior at Marked and Unmarked Crosswalks in the Tahoe Basin

Mitman, Meghan Fehlig
Cooper, Douglas
DuBose, Brooke
Pande, Swati
2010

For more than thirty years, pedestrian safety studies have considered pedestrian-vehicle collision history and pedestrian and driver behavior at marked and unmarked crosswalks at uncontrolled crossings. From 2005-2007, the UC Berkeley Traffic Safety Center, in a study funded by the California Department of Transportation (Caltrans), focused on developing a better understanding of driver and pedestrian behavior and safety in both marked and unmarked crosswalks in an effort to recommend more informed crosswalk policies. As a part of these efforts, a 2007 paper, “The Marked Crosswalk Dilemma...

Mixed Manual/Semi-Automated Traffic: A Macroscopic Analysis

Bose, Arnab
Ioannou, Petros
2001

The use of advanced technologies and intelligence in vehicles and infrastructure could make the current highway transportation system much more efficient. Semi-automated vehicles with the capability of automatically following a vehicle in front as long as it is in the same lane and in the vicinity of the forward looking ranging sensor are expected to be deployed in the near future. Their penetration into the current manual traffic will give rise to mixed manual/semi-automated traffic. In this paper, we analyze the fundamental flow-density curve for mixed traffic using flow-density curves...

Congestion-Responsive On-Ramp Metering: Recommendations toward a Statewide Policy

Lu, Xiao-Yun
Amini, Zahra
Mauch, Michael
Skabardonis, Alexander
2019

The objective of this project was to develop recommendations toward a statewide policy of congestion responsive freeway ramp metering (CRRM) operation. The research has been performed in the following approaches: First an empirical “before” and “after” freeway corridor performance evaluation was performed on a selected set of California’s freeway corridors that had implemented congestion responsive ramp metering. Next, other important policy and operational factors that impact the effectiveness of extended hours ramp metering were evaluated: traffic detector health and data quality and...

Integrated Ramp Metering Design and Evaluation Platform with Paramics

Chu, Lianyu
Recker, Will
Yu, Guizhen
2009

Ramp metering has been recognized as an effective freeway management strategy to either avoid or ameliorate freeway traffic congestion by limiting access to the freeway. California has applied ramp metering widely in major metropolitan areas. Currently, California has three major ramp metering systems: San Diego Ramp Metering System (SDRMS), Semi-Actuated Traffic Management System (SATMS), and Traffic Operations System (TOS). Although the ramp metering algorithms that underlay these systems are based on relatively simple theoretical concepts, these real-world ramp metering systems are...

Development and Testing of Field-Deployable Real-Time Laser-Based Non-Intrusive Detection System for Measurement of True Travel Time on the Highway

Cheng, Harry H.
Shaw, Ben
Palen, Joe
Hu, Xudong
Lin, Bin
Larson, Jonathan E.
Van Katwyk, Kirk
2001

We have developed a field prototype of a laser-based non-intrusive detection system for real-time measurement of delineations of moving vehicles for highway testing, based on our previous research on the laboratory prototype of the system. The primary goal of this project is to develop a roadway detection system that can be used to gather reliable travel time data non-intrusively. The system uses a laser line that is projected onto the ground as a probe. The reflected light is collected and focused into a photodiode array by an optical system. Vehicle presence is detected based on the...

Expedited Crash Investigation - With Use of Technologies for Documentation and Processing

Chan, Ching-Yao
Lian, Thang
Ko, Jeff
2007

The mobility and efficiency of California highways are impeded by the recurrent and non-recurrent congestion on a daily basis. Roadway incidents, especially collisions, often result in traffic congestion and travel delays. This project is initiated to explore the use of technologies that will potentially bring direct and immediate benefits to the law enforcement officers and other personnel who are involved in the handling of collision sites and subsequent investigations. The work carried out in this project includes three major components: (1) The experimentation of integrated vehicular...