Traffic Operations and Management

Two Proposals to Improve Freeway Traffic Flow

Karaaslan, Ufuk
Varaiya, Pravin
Walrand, Jean
1990

The following two proposals are presented: (1) Vehicles are organized in platoons in which the lead car is manually driven and the other cars are under automatic spacing (headway) control. A plausible model of the resulting flow of traffic indicates that, for an average platoon size of 20, the capacity of the freeway increases by a factor of four. (2) A macroscopic model of freeway traffic congestion along with a control law for reducing congestion is presented. Simulation of the resulting closed loop model indicates a dramatic reduction in congestion.

Turning Movement Estimation in Real Time (TMERT)

Martin, Peter T.
1995

This report describes the development of a new model that can monitor system performance and derive management and control strategies in real time. It presents the TMERT (Turning Movement Estimation in Real Time) model, a method of estimating turning movement flows from link detected flows at small recurrent intervals, in real time.

TravInfo Evaluation (Technology Element) Traveler Information Center (TIC) Study (September 1996 - June 1997)

Miller, Mark A.
Loukakos, Dimitri
1998

TravInfo is a Field Operational Test of advanced traveler information systems for the San Francisco Bay Area, sponsored by the Federal Highway Administration (FHWA). The project involves a public/private partnership which seeks to compile, integrate and broadly disseminate timely and accurate multi-modal traveler information through commercial products and services. The public sector component centers on the Traveler Information Center (TIC), which collects and integrates both static and dynamic traveler information. The TIC began operations in September 1996 and will operate as an FOT...

Traffic Management Systems Performance Measurement: Final Report

Banks, James H.
Kelly, Gregory
1997

This report documents a study of performance measurement for Transportation Management Centers (TMCs). Performance measurement requirements were analyzed, data collection and management techniques were investigated, and case study traffic data system improvement plans were prepared for two Caltrans districts.

Driving Safely in Smart Cars

Puri, Anuj
Varaiya, Pravin
1995

This paper considers the issue of safety in Automated Vehicle Highway Systems (AVHS). An approach is proposed for proving that a system is safe. The design for a proposed AVHS is considered and shown that if the physical controllers in the vehicles satisfy a set of constraints then the AVHS is safe. The authors contend that the problem of checking whether the controllers satisfy the constraints is equivalent to solving an optimal control problem.

Development of Integrated Meso/Microscale Traffic Simulation Software for Testing Fault Detection and Handling in AHS

Horowitz, Roberto
2004

In this report, we describe the research carried out under PATH Task Order 4208. The objective of this project was to bridge the gap between the Automated Highway System (AHS) simulators SmartAHS and SmartCAP, by implementing an integrated AHS micro-meso simulation environment for analyzing a large-scale AHS network. In fulfillment of this goal, a meso-microscale traffic simulator was developed that allows a stationary region of microsimulation to be defined within a larger, mesosimulated AHS. This simulator permits analysis of traffic behavior in situations where both vehicle-level (...

Identifying Density-Flow Relations on Arterial Surface Streets

Ahn, Soyoung
Cassidy, Michael J.
2002

A simple car-following rule was verified by studying vehicles discharging from long queues at signalized intersections. These observations indicated that the time-space trajectory of a jth vehicle discharging on a homogeneous intersection approach was essentially the same as the j−1th vehicle except for a translation in space and time. This is in agreement with a simplified theory proposed by G.F. Newell. The finding indicates that the congested branch of a density-flow curve is linear in form.

A Comparison of Traffic Models: Part 1, Framework

Lo, Hong K.
Lin, Wei-hua
Lawrence, C.
Chang, Elbert
Tsao, Jacob
1996

This report defines a framework for comparing dynamic traffic models. It emphasizes four dimensions: functionality, traffic dynamics, route choice dy namics, and overall network performance. The first dimension compares the models through a check-list of model functions. Regarding the last three comparison dimensions, a total of five networks and twelve scenarios are defined. These test scenarios are designed to accentuate model properties and differences. Also included in the report are a list of performance measures for comparison purpose, and a discussion of the interpretation of...

Bay Area Simulation and Ramp Metering Study - Year 2 Report

Gardes, Yonnel
Kim, Amy
May, Dolf
2003

As part of the California PATH program, the Paramics microscopic traffic simulation model was evaluated through a pilot application to the I-680 freeway corridor, one of the most highly congested facilities in the San Francisco Bay Area. The main objective of the project was to test the capability of the model to serve as a tool for evaluating alternative transportation planning and traffic management scenarios. HOV lanes were investigated first on a "simple" network, and later on the existing I-680 corridor. An Application Programming Interface (API) "plugin" designed by Quadstone, which...

Evaluation of On-Ramp Control Algorithms

Zhang, Michael
Kim, Taewan
Nie, Xiaojian
Jin, Wenlong
Chu, Lianyu
Recker, Will
2001

The control of a traffic corridor, which consists of two major component - freeway system control and arterial street system control, aims to improve flows on both freeway and arterial streets, and has been demonstrated as an effective means to increase the level of service of a corridor system during peak periods. Ramp metering, or ramp control, has been considered to be a very important component of corridor traffic control. Ramp metering is the application of control devices such as metering signals to limit the number of vehicles entering a freeway. The fundamental philosophy of ramp...