Traffic Operations and Management

Reduce Emissions and Improve Traffic Flow Through Collaborative Autonomy

April 30, 2024

Authors: Anthony D. Patire, Ph.D., Research and Development Engineer, PATH, University of California, Berkeley; Francois Dion, Ph.D., Research and Development Engineer, PATH, University of California, Berkeley; and Alexandre M. Bayen, Ph.D., Associate Provost for Moffett Field Program Development, University of California, Berkeley.

Abstract:

This report explores opportunities for employing autonomous driving technology to dampen stopandgo waves on freeways. If successful, it could...

Reduce Emissions and Improve Traffic Flow Through Collaborative Autonomy

Patire, Anthony D., PhD
Dion, Francois, PhD
Bayen, Alexandre M., PhD
2024

This report explores opportunities for employing autonomous driving technology to dampen stop-and-go waves on freeways. If successful, it could reduce fuel consumption and emissions. This technology was tested in an on-road experiment with 100 vehicles over one week. Public stakeholders were engaged to assess the planning effort and feasibility of taking the technology to the next level: a pilot involving 1000+ vehicles over several months. Considerations included the possible geographical boundaries, target fleets of vehicles, and suitable facilities such as bridges or managed lanes. Flow...

Vehicle Reidentification and Travel Time Measurement on Congested Freeways

Coifman, Benjamin
Cassidy, Michael
2002

The paper presents an algorithm for matching individual vehicles measured at a freeway detector with the vehicles’ corresponding measurements taken earlier at another detector located upstream. Although this algorithm is potentially compatible with many vehicle detector technologies, the paper illustrates the method using existing dual-loop detectors to measure vehicle lengths. This detector technology has seen widespread deployment for velocity measurement. Since the detectors were not developed to measure vehicle length, these measurements can include significant errors. To overcome this...

Freeway On-Ramp Metering, Delay Savings, and Diverge Bottleneck

Cassidy, Michael J.
2003

An effort was made to clarify certain issues concerning freeway onramp metering and its potential for saving commuter delay. Simple analogies were used to show that delay is reduced if ramp metering increases the rates at which commuters exit the freeway. Contrary to what is frequently reported in the literature, higher travel speeds and flows on links within a freeway system are not evidence of diminished delay and this too was made clear by the analogies. The discussion explains why a metering scheme should be specially tailored to the freeway it serves, and why no single metering logic...

Validation of Daganzo's Behavioral Theory of Multi-Lane Traffic Flow: Final Report

Banks, James H.
Amin, Mohammad R.
Cassidy, Michael J.
Chung, Koohong
2003

A study was conducted to verify C. F. Daganzo's behavioral theory of multi-lane traffic flow (1, 2). This study was conducted by teams from San Diego State University and the University of California at Berkeley who worked independently on a series of case studies to test predictions derived from the theory. The results of the study suggest that some of the phenomena predicted by Daganzo do occur, but not at all locations, and that the underlying behavioral assumptions are oversimplified. Specifically, the types of flow- density (or flow-occupancy) relationship assumed by Daganzo were...

Stationary Models of Unqueued Freeway Traffic and Some Effects of Freeway Geometry

Cassidy, Michael J.
Anani, Shadi B.
2003

Occupancies and flows were jointly sampled from numerous freeway segments in nearly stationary, unqueued traffic. The data from one segment were typically averaged across all lanes there and plotted. Each plot was compared with one sampled at a neighboring freeway segment, with the two segments differing only in their number of travel lanes. Such comparisons were repeated for a total of five pairs of segments on five freeways in and near Toronto, Canada and in California. All occupancy-flow relations were piece-wise linear in form for average flows up to about 2,000 vehicles per hour per...

Stationary Models of Unqueued Traffic and Number of Freeway Travel Lanes

Anani, Shadi B.
Cassidy, Michael J.
2005

Occupancies and flows were jointly sampled from freeway segments in nearly stationary, unqueued traffic. When plots of occupancy per lane versus flow per lane were normalized by n (the number of travel lanes in the freeway segment from which a data set came), the plots took shapes that were piecewise linear in form (except for conditions that were near capacity) and were clearly influenced by n. Drivers adopted a higher speed (for a given occupancy) while traveling on segments of greater n. Yet, the speeds on these wider segments exhibited greater sensitivity: drivers began decelerating at...

TRICEPS: An ATMIS Field Implementation for Control and Evaluation: Final Report

McNally, M. G.
Rindt, C.
Logi, F.
2002

This report summarizes a comprehensive research project directed toward the development and implementation of an Advanced Transportation Management and Information System (ATMIS) as part of the Caltrans Advanced ATMIS Testbed Program at the Institute of Transportation Studies, University of California, Irvine. The primary goal of this project was to implement this prototype ATMIS, designated TRICEPS (Testbed Realtime Integrated Control and Evaluation Prototype System), in the Irvine sub-area of the Advanced Testbed network. This sub-area represents a well-defined freeway corridor with a...

On-Ramp Metering Experiments to Increase Freeway Merge Capacity

Cassidy, Michael J.
Rudjanakanoknad, Jittichai
2005

Observations of two freeway/on-ramp merges unveil the mechanism that causes their capacities to diminish when queues form just upstream. Field experiments at one of the sites demonstrate that by responding to occupancies measured near the merge, ramp metering can reverse this mechanism, or postpone its occurrence, and thereby generate higher merge capacities. Detailed observations at the second site imply that higher merge capacities can also be achieved using traffic control schemes that regulate inflows to the merge from the freeway shoulder lane. Collectively, the findings point to...

Empirical Reassessment of Traffic Operations: Freeway Bottlenecks and the Case for HOV Lanes

Cassidy, Michael J.
Daganzo, Carlos F.
Jang, Kitae
Chung, Koohong
2006

An earlier empirical study of San Francisco Bay Area freeways concluded that HOV lanes unfavorably affect freeway traffic by creating congestion. That study attributed the observed congestion to HOV lanes and tentatively recommended their elimination over the full lengths of the freeways it examined; and even from all Bay Area freeways. It recognized, however, that its analysis is fragmentary and recommended further work to solidify its conclusions. This is logical since the study lacks a spatiotemporal analysis to pinpoint where and how congestion first forms (at bottlenecks).The present...