Sharif Digital Repository

Optimizing highway alignment requires a versatile set of cost functions and an efficient search method to achieve the best design. Because of numerous highway design considerations, this issue is classified as a constrained problem. Moreover, because of the infinite number of possible solutions for the problem and the continuous search space, highway alignment optimization is a complex problem. In this study, a customized particle swarm optimization algorithm was used to search for a near-optimal highway alignment, which is a compound of several tangents, consisting of circular (for horizontal design) and parabolic (for vertical alignment) curves. The selected highway alignment should meet... 

This paper studies the transit network scheduling problem and aims to minimize the waiting time at transfer stations. First, the problem is formulated as a mixed integer programming model that gives the departure times of vehicles in lines so that passengers can transfer between lines at transfer stations with minimum waiting times. Then, the model is expanded to a second model by considering the extra stopping time of vehicles at transfer stations as a new variable set. By calculating the optimal values for these variables, transfers can be better performed. The sizes of the models, compared with the existing models, are small enough that the models can be solved for small- and medium-sized... 

Estimanon of the origin-destination trip danad matrix (O-D) plays a key role in travel analysis and transportation planning and operations. Many researchers have developed different O-D maths estimation mediods using traffic counts, which allow simple data collection as opposed to die costly traditional direct estimation methods based on home and roadside interviews. In mis papet, a new fuzzy O-D matrix estimation model (FODMEM) is proposed to estimate die O-D matrix from traffic count. A gradient-based aigoridnn. containing 3 fuzzy rule based approach to control die estimated O-D matrix changes, is proposed to solve FODMEM Since link data only represents a snapshot situation, resulting in... 

Railway managers have a strong economic incentive to minimize track maintenance costs, while maintaining safety standards and providing adequate service levels to train operators. The objective of this study is to apply a procedure for making optimal maintenance decisions in Iranian Railways. This study consists of two parts. First, a cumulative damage model, based on a Markov process, is applied to model the deterioration of the track. For this reason, tracks are categorized into six classes, so that those tracks with similar traffic loads and geographical location are collected into one class. The track survey data from 215 blocks (4,228 km) of the ten divisions of the Iranian Railway... 

Traffic assignment is one of the primary steps in the urban transportation planning process. There are several parameters that affect on drivers route choice. These factors arenot shown completely in the classic traffic assignment techniques so, these methodes donot have acceptable accuracy in the link volume estimating. Therefore many researchers have been tried to use fuzzy set theory in order to gain more precise approximation in traffic assignment. In this paper, we intend to propose a new fuzzy assignment model which has more flexibility relarive to driver behavior characteristics. At first, our assumptions are cited and then we illustrate how the membership function of the travel time... 

This paper applies the genetic-fuzzy and neuro-fuzzy systems to analyze a disaggregate mode choice problem for work trips. These two artificial intelligence methods have been widely used in many complex engineering problems recently. Some key points in developing genetic-fuzzy and neuro-fuzzy systems to analyze the mode choice problem for a large city are explained. Shiraz urban trips database is applied to prepare the data needed for the models. Results show that the developed models have good ability to estimate the existing situation and also to present reliable predictions for the future conditions of an urban transportation system  

The Population Growth, Land-use Development and the Increase in Vehicle Ownership in big cities have caused an increase in Travel Demand and the volume of vehicles passing through Urban Routes. Travel Time in the urban route network due to increase in congestion in one of the most important problems in Metropolises. A considerable part of Travel Time in the Metropolitan routes network is related to delay time in intersections. Thus, controlling methods for intersections in order to decrease such delays is of a great importance. The application of Fuzzy Logic as a control basis in engineering issues has a proper background. In this study, a method for controlling such signalized intersections...