Traffic Operations and Management

Logistics Systems Analysis

Carlos Daganzo
2005

This expanded edition of A Logistics Systems Analysis@ includes new - search results and numerous modifications to enhance comprehensiveness and clarity. It has two new sections, a new appendix, and more than half a dozen new figures. A few references have also been added, but the bibli- raphy is not exhaustive. Much of the new material is based on work by Profs. Alan Erera (Georgia Tech), Karen Smilowitz (Northwestern U. ), and by PhD candidate Yanfeng Ouyang (U. C. Berkeley). Their help is gratefully acknowledged. The financial support of the National Science Foundation and the...

Moving Bottlenecks: A Numerical Method that Converges in Flows

Carlos Daganzo
Laval, Jorge A.
2005

This paper presents a numerical method to model kinematic wave (KW) traffic streams containing slow vehicles. The slow vehicles are modeled discretely as moving boundaries that can affect the traffic stream. The proposed scheme converges in flows, densities and speeds without oscillations, and therefore can be readily used in situations where one wishes to model the effect of the traffic stream on the bottlenecks too.

Improving City Mobility Through Gridlock Control: An Approach and Some Ideas

Carlos Daganzo
2005

This paper examines the effect of gridlock on urban mobility. It defines gridlock and shows how it can be modeled, monitored and controlled with parsimonious models that do not rely on detailed forecasts. The proposed approach to gridlock management should be most effective when based on real-time observation of relevant spatially aggregated measures of traffic performance. This is discussed in detail. The ideas in this paper suggest numerous avenues for research at the empirical and theoretical levels. An appendix summarizes some of these.

Taming the Bullwhip Effect : From Traffic to Supply Chains

Ouyang, Yanfeng
Lago, Alejandro
Carlos Daganzo
2006

Bus Lanes with Intermittent Priority: Strategy Formulae and an Evaluation

Eichler, Michael
Carlos Daganzo
2006

This paper evaluates strategies for operating buses on signal-controlled arterials using special lanes that are made intermittently available to general traffic. The advantage of special bus lanes, intermittent or dedicated, is that they free buses from traffic interference; the disadvantage is that they disrupt traffic. We find that bus lanes with intermittent priority (BLIPs), unlike dedicated ones, do not significantly reduce street capacity. Intermittence, however, increases the average traffic density at which the demand is served, and as a result increases traffic delay. These delays...

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

Michael Cassidy
Carlos Daganzo
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...

Impacts of Lane Changes at Merge Bottlenecks: A Theory and Strategies to Maximize Capacity

Laval, Jorge
Michael Cassidy
Carlos Daganzo
Schadschneider, Andreas
Pöschel, Thorsten
Kühne, Reinhart
Schreckenberg, Michael
Wolf, Dietrich E.
2007

Recent empirical observations at freeway merge bottlenecks have revealed (i) a drop in the bottleneck discharge rate when queues form upstream, (ii) an increase in lane-changing maneuvers simultaneous with this “capacity drop”, and (iii) a reversal of the drop when the ramp is metered.

Urban Gridlock: Macroscopic Modeling and Mitigation Approaches

Carlos Daganzo
2007

This paper describes an adaptive control approach to improve urban mobility and relieve congestion. The basic idea consists in monitoring and controlling aggregate vehicular accumulations at the neighborhood level. To do this, physical models of the gridlock phenomenon are presented both for single neighborhoods and for systems of inter-connected neighborhoods. The models are dynamic, aggregate and only require observable inputs. The latter can be obtained in real-time if the neighborhoods are properly instrumented. Therefore, the models can be used for adaptive control. Experiments should...

Spillovers, Merging Traffic and the Morning Commute

Lago, Alejandro
Carlos Daganzo
2007

Theoretical studies of the morning commute for mono-centric cities have ignored that drivers choose their home departure times knowing that they must compete with other drivers for road space, which becomes scarcer with proximity to the center. This paper examines two important aspects of this competition: queue spillovers caused by insufficient road space, and merging interactions caused by the convergence of trips. For maximum transparency the paper focuses on an idealized two-origin, single-destination network with limited storage space because this system exhibits all the essential...

Deploying Lanes for High Occupancy Vehicles in Urban Areas

Michael Cassidy
Carlos Daganzo
2007

Simulations and field experiments in previous works suggest that a freeway’s general purpose lanes (those not dedicated to high occupancy vehicles) discharge vehicles from bottlenecks at an equal or higher average rate when one of the lanes is devoted to high occupancy vehicles than when it is not. This result was used in these previous works to develop formulae for the total discharge rate of bottlenecks, with and without dedicated lanes, as a function of the percentage of high occupancy vehicles in the traffic stream.This present paper extends these ideas by examining the effect of...