Traffic Theory

A Behavioral Theory of Multi-Lane Traffic Flow Part II: Merges and the Onset of Congestion

Daganzo, Carlos F.
1999

This paper examines the behavior of multi-lane freeway traffic past on-ramps, building on the continuum model of part I and focusing on the onset of congestion. The main complication with merges is that rabbits (fast vehicles) entering from an on-ramp usually stay on the shoulder lane(s) of the freeway for some distance before merging into the fast lane(s). An idealization is proposed where this distance is taken to be the same for all vehicles. As a result, the system behaves as if there was a fixed buffer zone where entering rabbits cannot change lanes. The model of part I is extended to...

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.

Critique of a Freeway On-Ramp Metering Scheme and Broader Related Issues

Cassidy, Michael J.
2002

Offered here is a critique of a simple scheme recently proposed for metering freeway on-ramps. An earlier report of this scheme's potential for reducing commuter delay is shown to be exaggerated. The discussion makes clear that to reduce delay, metering should increase the rates at which commuters exit the freeway. The scheme critiqued here, as well as other well-known metering algorithms, are shown to have deficiencies in this, particularly when the freeway is plagued by a diverge bottleneck with a congested off-ramp. Other more effective schemes for reducing the delay caused by these...

A Network Model of Departure Time Choice with Spillovers and Merging Effects. Part I: Building Block

Lago, Alejandro
Daganzo, Carlos F.
2003

This paper presents a departure-time user equilibrium model that explicitly considers the most important determinants of congestion behavior in cities during the morning commute: different commuter origins, merge interactions and queue spillovers. The proposed model combines three previous works: the departure-time equilibrium theory in Vickrey (1969), the traffic flow model of Newell (1993) and the merge theory in Daganzo (1996). The paper examines the simplest possible network exhibiting the three important features and discusses the ensuing policy implications. The solution algorithm...

Moving Bottlenecks: A Numerical Method that Converges in Flows

Daganzo, Carlos F.
Laval, Jorge A.
2003

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. The approach is more accurate than Godunov's method in situations where the latter can be applied.

Distributing Synchronous Programs Using Bounded Queues, a coordinated traffic signal application

Zennaro, Marco
Sengupta, Raja
2005

This paper is about the modular compilation and distribution of a sub-class of Simulink programs [10] across networks using bounded FIFO queues. The problem is first addressed mathematically. Then, based on these formal results, a software library for the modular compilation and distribution of Simulink program is given. The performance the library is given. The value of synchronous programming for the next generation of traffic control value is discussed. The adoption of these tools seems to be the natural candidate to address the needs of the traffic engineers. As a case study we present...

Counteracting the Bullwhip Effect with Decentralized Negotiations and Advance Demand Information

Ouyang, Yanfeng
Daganzo, Carlos
2005

This paper shows how to reduce the bullwhip effect by introducing advance demand information (ADI) into the ordering schemes of supply chains. It quantifies the potential costs and benefits of ADI, and demonstrates that they are not evenly distributed across the chain. Therefore, market-based strategies to re-distribute wealth without penalizing any supplier are presented. The paper shows that if a centralized operation can eliminate the bullwhip effect and reduce total cost, then some of this reduction can also be achieved with decentralized negotiation schemes. Their performance is...

A Variable Formulation of Kinematic Waves: Solution Methods

Daganzo, Carlos F.
2003

This paper presents improved solution methods for kinematic wave trafficc problems with concave flow-density relations. As explained in part I of this work, the solution of a kinematic wave problem is a set of continuum least-cost paths in space-time. The least cost to reach a point is the vehicle number. The idea here consists in overlaying a dense but discrete network with appropriate costs in the solution region and then using a shortest-path algorithm to estimate vehicle numbers. With properly designed networks, this procedure is more accurate than existing methods and can be applied...

Dashboard Cameras Combined with AI Provide an Affordable Method for Identifying Curb Usage

Arcak, Murat
Kurzhanskiy, Alexander
2024

The increasing reliance on transportation network companies (TNCs) and delivery services has transformed the use of curb space. The curb space is also an important interface for bikeways, bus lanes, street vendors, and paratransit stops for passengers with disabilities. These various demands are contributing to a lack of parking, resulting in illegal and double-parking and excessive cruising for spaces and causing traffic disturbance, congestion, and hazardous situations. How cities manage this public asset to support safety and the local economy relies on first understanding the usage...

Distance-dependent Congestion Pricing for Downtown Zones

Daganzo, Carlos F
Lehe, Lewis J
2014

A growing literature exploits macroscopic theories of traffic to model congestion pricing policies in downtown zones. This study introduces trip length heterogeneity into this analysis and proposes a usage-based, time-varying congestion toll that alleviates congestion while prioritizing shorter trips. Unlike conventional trip-based tolls the scheme is intended to align the fees paid by drivers with the actual congestion damage they do, and to increase the toll’s benefits as a result. The scheme is intended to maximize the number of people that finish their trips close to their desired...