scholarly journals System Optimum Fuzzy Traffic Assignment Problem

2019 ◽  
Vol 31 (6) ◽  
pp. 611-620
Author(s):  
Gizem Temelcan ◽  
Hale Gonce Kocken ◽  
Inci Albayrak
Keyword(s):  
Travel Time ◽  
Assignment Problem ◽  
Road Network ◽  
Traffic Assignment ◽  
Triangular Fuzzy Numbers ◽  
System Optimum ◽  
Average Speed ◽  
Traffic Assignment Problem ◽  
Path Lengths ◽  
Link Travel Time

This paper focuses on converting the system optimum traffic assignment problem (SO-TAP) to system optimum fuzzy traffic assignment problem (SO-FTAP). The SO-TAP aims to minimize the total system travel time on road network between the specified origin and destination points. Link travel time is taken as a linear function of fuzzy link flow; thus each link travel time is constructed as a triangular fuzzy number. The objective function is expressed in terms of link flows and link travel times in a non-linear form while satisfying the flow conservation constraints. The parameters of the problem are path lengths, number of lanes, average speed of a vehicle, vehicle length, clearance, spacing, link capacity and free flow travel time. Considering a road network, the path lengths and number of lanes are taken as crisp numbers. The average speed of a vehicle and vehicle length are imprecise in nature, so these are taken as triangular fuzzy numbers. Since the remaining parameters, that are clearance, spacing, link capacity and free flow travel time are determined by the average speed of a vehicle and vehicle length, they will be triangular fuzzy numbers. Finally, the original SO-TAP is converted to a fuzzy quadratic programming (FQP) problem, and it is solved using an existing approach from literature. A numerical experiment is illustrated.

Trial-and-Error Procedure for Implementing a Road-Pricing Scheme

2005 ◽  
Vol 1923 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Qiang Meng ◽  
Wei Xu ◽  
Hai Yang
Keyword(s):  
Travel Time ◽  
Assignment Problem ◽  
Traffic Assignment ◽  
Road Pricing ◽  
User Equilibrium ◽  
Trial And Error ◽  
Traffic Flows ◽  
The Road ◽  
Traffic Assignment Problem ◽  
Pricing Scheme

This paper deals with a road-pricing scheme that aims at alleviating congestion phenomena or air and noise pollution in some areas of a transportation network in such a way that the volumes of traffic flow on entry links to these areas do not exceed their respective predetermined thresholds by levying appropriate tolls at these links. This paper begins to show that the road-pricing scheme is equivalent to a problem that determines optimal Lagrangian multipliers for a user equilibrium traffic assignment problem with link capacity constraints. It then proceeds to devise a novel trial-and-error procedure requiring observed traffic flows at the entry links only, to identify a solution for the road-pricing scheme when link travel time functions, origin–destination demand functions, and users’ value of travel time are unknown. The procedure is as follows. A trial on a set of given tolls is conducted, and then the resultant link flows are observed. According to these observed traffic flows, a new set of tolls for the next trial is adjusted by executing a simple projection operation. The trial-and-error procedure is, in fact, a variation of a gradient projection method for dual formulation of the traffic assignment problem, and its convergence can be guaranteed under mild conditions. Accordingly, a conjecture for the convergence of trial-and-error implementation of the congestion pricing proposed by economists is rigorously proved. Furthermore, the iterative procedure presented in this paper in practice can facilitate the estimation of such tolls by land transport authorities.

scholarly journals Competitive Traffic Assignment in Road Networks

2016 ◽  
Vol 17 (3) ◽  
pp. 212-221 ◽  
Author(s):  
Alexander Y. Krylatov ◽  
Victor V. Zakharov ◽  
Igor G. Malygin
Keyword(s):  
Nash Equilibrium ◽  
Assignment Problem ◽  
Traffic Assignment ◽  
User Equilibrium ◽  
Urban Traffic ◽  
Route Guidance ◽  
Theoretic Approach ◽  
System Optimum ◽  
Traffic Assignment Problem ◽  
Route Choices

Abstract Recently in-vehicle route guidance and information systems are rapidly developing. Such systems are expected to reduce congestion in an urban traffic area. This social benefit is believed to be reached by imposing the route choices on the network users that lead to the system optimum traffic assignment. However, guidance service could be offered by different competitive business companies. Then route choices of different mutually independent groups of users may reject traffic assignment from the system optimum state. In this paper, a game theoretic approach is shown to be very efficient to formalize competitive traffic assignment problem with various groups of users in the form of non-cooperative network game with the Nash equilibrium search. The relationships between the Wardrop’s system optimum associated with the traffic assignment problem and the Nash equilibrium associated with the competitive traffic assignment problem are investigated. Moreover, some related aspects of the Nash equilibrium and the Wardrop’s user equilibrium assignments are also discussed.

scholarly journals A Mixed Integer Linear Program for the Single Destination System Optimum Dynamic Traffic Assignment Problem with Physical Queue

2012 ◽  
Vol 22 (4) ◽  
pp. 245-249 ◽  
Author(s):  
Shuguang Li ◽  
Qing-Hua Zhou ◽  
Yongfeng Ju
Keyword(s):  
Assignment Problem ◽  
Traffic Assignment ◽  
Dynamic Traffic Assignment ◽  
Dynamic Network ◽  
Linear Program ◽  
Mixed Integer ◽  
Dynamic Traffic ◽  
System Optimum ◽  
Mixed Integer Linear Program ◽  
Traffic Assignment Problem

In order to solve the system optimum dynamic traffic assignment problem, the whole link model with physical queue is used to formulate the single destination system optimum dynamic traffic assignment problem as a mixed linear program. A relationship between the cumulative curves and the wave speed presented by Newell (1993) is used to present a dynamic network model in considering spillback queue. And nonlinear constrains are relaxed into mixed linear constrains; the linear program software is used to solve the system optimum dynamic traffic assignment problem. A numerical example illustrates the simplicity and applicability of the proposed approach. KEYWORDS: Dynamic System Optimum Traffic Assignment; physical queue; mixed integer linear programming

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