Traffic Operations and Management

An Electronic Surveillance and Control System for Traffic Management on the Borman Expressway. Part II, Calibrating a Simulation Model

Wang, Mu-Han
Cassidy, Michael J.
1995

This report presents a project whose purpose was to calibrate a freeway simulation model to emulate traffic operating conditions on the Borman Expressway. The computer simulation model can then be used to predict impacts created by a host of possible conditions including incident occurrences, maintenance, reconstruction and the deployment of various freeway control and management strategies. The results of the simulation model can be used as a decision-making tool for adopting suitable policies to address operating needs.

Improved Strategies for Deploying Vehicle-Actuated Control at Isolated Signalized Intersections

Cassidy, Michael
Chuang, Yu-Hao
Vitale, Jeff
1995

This research has sought to demonstrate potential benefits from deploying enhanced vehicle actuation strategies at isolated signalized intersections. The work has exploited microscopic, stochastic simulation to evaluate impacts of enhanced vehicle-actuated (VA) control schemes for an array of operating conditions. Simulated outcomes (i.e. average vehicle delays) generated under the enhanced strategies were compared with outcomes resulting from more “conventional VA control policies. Findings from this work suggest that substantial delay reduction generally occurs by exploiting VA...

Evaluating Steady-State Assumption for Highway Queueing System

Son, Young Tae
Cassidy, Michael J.
Modanat, Samer M.
1995

Stochastic queueing methods are often applied to highway systems to estimate performance characteristics such as delay and queue length.

Unique Bivariate Relationships in Highway Traffic

Cassidy, Michael J.
1996

Decision-Making System for Freeway Incident Response Using Sequential Hypothesis Testing Methods

Madanat, Samer M.
Cassidy, Michael J.
Teng, Hua-Liang
Liu, Pen-Chi
1996

Recent research in advanced traffic management systems has emphasized incident detection and response to mitigate nonrecurring congestion. Existing incident response decision-making algorithms do not account for the expected losses associated with false alarms, undetected incidents, and delayed incident response. A freeway incident response decision-making system based on sequential hypothesis testing techniques is presented. The primary feature of this decision-making system is that it minimizes the sum of the expected losses associated with false response, nonresponse, and delayed...

Application of Ordered Probit Techniques to Analyze Ratings of Blissymbol Complexity

Soto, Gloria
Cassidy, Michael
Madanat, Samer
1996

This paper explores the application of ordered probit modeling, an econometric technique commonly used for the analysis of rating data in situations when respondents are asked to rate items (e.g., an object, service, or product), one at a time. To demonstrate the application of this methodology, an existing data set, originally collected to measure the perceived complexities for an array of Blissymbols, was used. Findings from the use of the ordered probit model are compared with those resulting from the earlier research that used regression procedures. Results from the use of ordered...

Reexamining Vehicle-Actuation Strategies at Isolated Signalized Intersections

Cassidy, Michael
Chuang, Yu-Hao
Vitale, Jeff
1996

This paper uses simulation to assess intersection performance under enhanced vehicle-actuated signal control. The enhanced strategies seek to: (1) terminate green time in such a way as to promote use of the clearance interval by discharging vehicles.

Bivariate Relations in Nearly Stationary Highway Traffic

Cassidy, Michael J.
1998

This paper demonstrates that reproducible bivariate relations exist among traffic variables, such as flow and occupancy, when traffic conditions are approximately stationary. The inspection of cumulative curves of vehicle arrival number and vehicle occupancy has revealed that sustained periods of nearly stationary conditions do arise in the traffic stream. By plotting average values of the data corresponding to each nearly stationary condition, well-defined relations are observed. These scatterplots of near-stationary data are contrasted with plots of data that were measured over...

Possible Explanations of Phase Transitions in Highway Traffic

Daganzo, C. F.
Cassidy, M. J.
Bertini, R. L.
1999

It is shown that all the phase transitions in and out of freely flowing traffic reported earlier for a German site could be caused by bottlenecks, as are all the transitions observed at two other sites examined here. The evidence suggests that bottlenecks cause these transitions in a predictable way, and does not suggest that stoppages (jams) appear spontaneously in free flow traffic for no apparent reason. It is also shown that many of the complicated instability phenomena observed at all locations can be explained qualitatively in terms of a simple Markovian theory specific to traffic...

Observations at a Freeway Bottleneck

Cassidy, M. J.
Bertini, Robert L.
1999

Using transformed curves of cumulative vehicle count and cumulative occupancy, a study was conducted of traffic upstream and downstream of a bottleneck on a freeway in Toronto, Canada, located more than a kilometer downstream of a busy on-ramp. After diagnosing its location and the times that it remained active each day, the study focused on the traffic patterns that arose in each travel lane. It was observed that prior to the bottleneck's activation, vehicle lane-changing trends created extraordinarily high flows in the median (i.e., left-most) lane and that these high flows were...