Sharif Digital Repository

Recent studies show that energy consumption of battery electric vehicles (BEVs) increases in traffic congestion. Therefore, it is important to consider the effect of link flow on BEV energy consumption. The flow-dependent energy consumption changes the route choice and user equilibrium conditions. In this paper, some shortcomings of available BEV flow-dependent energy consumption user equilibrium models are shown first. Then, “sufficient” as well as “sufficient and necessary” user equilibrium based on the generalized travel time of each path and sub-path penalties are defined and modeled for flow-dependent energy consumption. While it is difficult to solve the sufficient and necessary model,... 

The choice of technology to transport passengers in large metropolitan areas is an important issue everywhere. There are many factors involved in this choice. This paper deals with the possibility of the objective use of available information in the analysis of the suitability of a rail public transport system for a city. A database has been made from publications on public city transportation and country level information. Logit models of choice have been calibrated by the maximum likelihood and nonlinear least square methods based on the acquired information. Each city is treated as an "individual", choosing rail or non-rail modes for its trips. Only cities with a population of more than... 

The transit assignment process applied as part of the development of the Tehran transportation model is described. The process includes development of various models Tor dwell time as a function of transit volume. Dwell time is the time a transit vehicle spends at a stop to allow passengers to alight and board. This method was implemented by using EMME/2 transportation planning software. The calculation of dwell time is necessary in modeling transit assignment because an accurate estimation of dwell time will lead to more precise transit assignment results. The area analyzed in the model comprises various transportation analysis zones in the city of Tehran. The model output was shown to be... 

Braess' phenomenon, also known as Braess' paradox, is a phenomenon that has received considerable attention in transportation engineering and planning, as well as in other fields. It has an important implication in the area of investment in transportation networks, namely that adding a new link in a network may increase the cost to the users of that network. In this paper we show this phenomenon in a new environment. Unlike traditional examples, which involve the physical addition of a link to a network (a 0/1 integer decision variable), an example is presented where the decision variable is continuous in nature. Moreover, this example conveys two new messages. First, it is shown that some... 

In transportation literature, User Equilibrium (UE) has been widely studied since early 1950's, many studies of which define equilibrium flow of traffic for uncapacitated networks based on Wardrop's first principle, implying also a Nash Equilibrium (NE). Although, in general, the two equilibria (UE and NE) are not explicitly the same, they are shown to be equivalent under special conditions for uncapacitated UE, when volume delay functions are separable, continuous, non-decreasing and non-negative. A good deal of research is devoted to explain UE in capacitated networks based on Wardrop's first principle and the concept of generalized costs. However, UE for capacitated networks, even under... 

The trip demand information in the form of the origin-destination (OD) matrix is an essential input to the transportation studies. Obtaining such a matrix by conventional methods needs considerable amount of time, cost, and manpower. Since obtaining traffic volume data for the links of the transportation network is easy, recently many researchers have tried to obtain trip demand matrix by using this information. Among them, Spiess introduced the gradient method which is applicable for real large scale networks. The gradient method is an iterative procedure which starts from an initial O-D matrix and at each iteration tries to reach a matrix which generates flows closer to the observed flows... 

The vehicle routing problem (VRP) is one of the most complicated optimization mathematical models; the school bus routing problem (SBRP) is an important and practical branch of this problem. Because the number of variables and equations is vast, finding the exact solution for this problem under real conditions is difficult; only heuristic and metaheuristic algorithms can be used to solve it. Recently, the ejection chain method (ECM) has been introduced as a heuristic algorithm that efficiently finds a new neighbor solution. In a case study in developing countries, efficiency of several heuristic algorithms including ECM along with one metaheuristic algorithm-tabu search algorithm (TSA)-is... 

Improving the service quality of the public transport systems has always been an interesting research area in the field of transportation planning. Public transit system expansion and enhancement has been known as a recognized way to improve congested metropolitan areas. In order to make a transit system more attractive to people, both long and short term management strategies should be considered. Fleet re-assignment to a bus network, a noticeable component of the public transit system, was the focus of this study. It was introduced as a short term management strategy to help the operators maintain service quality without confusing the users by abrupt changes in the system. The proposed... 

In transportation literature, User Equilibrium (UE) has been widely studied since early 1950's, many studies of which define equilibrium flow of traffic for uncapacitated networks based on Wardrop's first principle, implying also a Nash Equilibrium (NE). Although, in general, the two equilibria (UE and NE) are not explicitly the same, they are shown to be equivalent under special conditions for uncapacitated UE, when volume delay functions are separable, continuous, non-decreasing and non-negative. A good deal of research is devoted to explain UE in capacitated networks based on Wardrop's first principle and the concept of generalized costs. However, UE for capacitated networks, even under... 

The equilibrium signal-setting problem is stated and subsequently formulated as a continuous equilibrium network design problem. The bilevel formulation is nonconvex and therefore cannot be solved for global optima by using descent solution algorithms. Therefore, a lower bound using a system optimal flow pattern is proposed that will be quite tight in both uncongested and highly congested network traffic situations. A solution algorithm based on the standard steepest-descent method is proposed for the lower-bound problem. Performance of the solution algorithm on a network problem is reported