Roads/Highways

A Proposed Analytical Technique for the Design and Analysis of Major Freeway Weaving Sections

Cassidy, Michael James
1990

Weaving occurs when merging traffic streams entering a freeway from an on-ramp cross over diverging traffic streams exiting the freeway via a nearby off-ramp. The intense lane-changing activity which typically occurs in weaving areas can create significant operational problems. Thus, weaving sections often represent bottleneck locations in urban freeway systems. The prevalence of weaving areas on U.S. freeways warrants the need for analytical techniques which can reliably analyze and/or design these critical freeway components. However, previous research at the Institute of Transportation...

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...

Causes And Effects Of Phase Transitions In Highway Traffic

Daganzo, C. F.
Cassidy, M. J.
Bertini, R. L.
1997

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. Furthermore, all the evidence indicates that bottlenecks cause these transitions in a predictable way, and no evidence is found that stoppages (jams) appear spontaneously in free flow traffic for no apparent reason. The most salient phenomena observed at all locations are explained in terms of a simple theory specific to traffic.

Design Of A Machine Vision-based, Vehicle Actuated Traffic Signal Controller

Cassidy, Michael
Coifman, Benjamin
1998

This project presents a signal controller algorithm to capitalize on the extended information provided by wide-area detection at isolated intersections. Using computer simulation, different control strategies are evaluated and the performance of the proposed wide-area detection system with conventional signal controllers is compared. The results indicate that wide-area vehicle actuated (VA) control can yield significant improvements over conventional VA control strategies.

Driver Memory: Motorist Selection and Retention of Individualized Headways in Highway Traffic

Cassidy, Michael J.
Windover, John R.
1998

The paper presents evidence that (1) drivers have different personalities in that they follow vehicles at different headways, and (2) drivers retain their personalities in that each driver tends to maintain his headway over space and, in some instances, drivers return to their headways after being forced by a traffic disturbance to alter them temporarily. This attribute, which we term driver memory, is revealed by visual inspection of modified curves of measured cumulative vehicle arrival number versus time.

Traffic Flow And Capacity

Cassidy, Michael J.
Hall, Randolph W.
1999

The design of highways, runways, ports or any transportation facility is guided by knowledge and theory of the traffic streams they serve. A facility’s scale, its geometry and its control measures are selected to affect certain properties of its traffic, such as the travel delay, the separation between vehicles, etc. In the case of highway traffic, the emphasis of this chapter, these are usually properties that are collected from, or averaged over, some number of vehicles. This is because the behavior of one driver differs from that of another, sometimes in complicated or even unexpected...

Some Observations of Highway Traffic in Long Queues

Smilowitz, Karen R.
Daganzo, Carlos F.
Cassidy, Michael J.
Bertini, Robert L.
1999

The arrival times of vehicles traveling southbound along a two-lane, bidirectional highway were recorded at eight neighboring locations upstream of a bottleneck caused by an oversaturated traffic signal. Cumulative curves constructed from these observations describe completely and in great detail the evolution of the resulting long queues. These queues formed directly upstream of the signal when the signal’s service rate fell below the southbound arrival rates, and never formed away from the bottleneck. The predictability of bottlenecks like the one studied here can be exploited to manage...

Some Traffic Features at Freeway Bottlenecks

Cassidy, Michael J.
Bertini, Robert L.
1999

Observations from two freeway bottlenecks in and near Toronto, Canada indicate that the average rate vehicles discharge from a queue can be 10% lower than the flow measured prior to the queue's formation. Absent any influences from downstream, the queue discharge flows exhibited nearly stationary patterns that alternated between higher and lower rates. These alternating flow patterns were especially evident at one of the two sites, although the feature occurred at both sites during periods that immediately followed the onset of upstream queueing; i.e. a queue's formation was always...