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zokaei-ashtiani--hedayat
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Total 328 records
A Heuristic Method for Coordination of Signalized Intersection
, M.Sc. Thesis Sharif University of Technology ; Zokaei Ashtiani, Hedayat (Supervisor)
Abstract
Signal coordination is one of the strategies to decrease the delay times in transportation networks. The application of dynamic traffic assignment has been made possible the modeling of flow loading in network links, and queue formation and dissipation in signalized intersections. In this thesis, signal offset set which produce the minimum total travel time in a network is determined, using a cell-based dynamic traffic assignment which is based on the cell transmission model. Genetic algorithm has been implemented to reach the suboptimal offset set. The application of the algorithm on a small test network shows that it can reach to an offset set with 1% error to the optimal offset set, by...
Solving Electric Vehicle Traffic Assignment Problem Considering Time-Dependent Energy Consumption
, M.Sc. Thesis Sharif University of Technology ; Zokaei Ashtiani, Hedayat (Supervisor)
Abstract
Battery Electric vehicles (BEVs) are turning into a more well known type of transportation because of their energy effectiveness, further sustainability, and the arrangement of government support through motivation programs. However, BEVs have a constrained driving range due to their limited battery capacity. This limited battery capacity leads to a fear of exhausting energy in the middle of route which is referred to as range anxiety. The range anxiety affects BEV users’ travel choices such as route choice. Hence, BEV users should consider their vehicles’ remaining range while trying to minimize their travel times. This concern consequently changes the equilibrium flow on the transportation...
Simultaneous Traffic Assignment Model for Autonomous Vehicles and Regular Vehicles with Different Route Choice Criteria in Transportation Network
, M.Sc. Thesis Sharif University of Technology ; Zokaei Ashtiani, Hedayat (Supervisor)
Abstract
With the arrival of autonomous vehicles in the fleet of the transportation network and the change of some travel parameters such as travel time, mode choice models, as well as route choice models, will also change. These types of vehicles will be able to move less distance from the front vehicle compared to regular vehicles. Also, due to the exchange of information between the vehicle and the infrastructure, we will see an increase in the capacity of the transportation network and its safety. The period of complete transition from regular vehicles to self-driving vehicles will be relatively important and therefore it is necessary to see these two phenomena together. It is assumed that...
Usage-based Nonlinear Pricing on Traffic Zones
, M.Sc. Thesis Sharif University of Technology ; Zokaei Ashtiani, Hedayat (Supervisor)
Abstract
Nowadays, the necessity of management tools for controlling the ever increasing congestions in transportation networks has been increased. Pricing is one of these tools for mitigating congestions in transportation networks. In this regard, different pricing models have been developed for transportation networks. By considering the advancement in technologies and possibility of recording the vehicles’ traveled distance in the tolling areas, the amount of toll each user pays could be a nonlinear function of the distance traveled inside tolling areas. As a result, the generalized travel cost of each path may not be link-wise additive; therefore, the resulting shortest path problem cannot be...
Routing and Schedueling for Hazardous Materials Shipment
,
M.Sc. Thesis
Sharif University of Technology
;
Zokaei Aashtiani, Hedayat
(Supervisor)
Abstract
Shipment of hazardous materials has got an important role in the world of today. Nowadays, sustainable development has got serious attention, and human health and environment are one of the sustainable development bases. The risk of hazardous materials for human health and environment, and also importance of this kind of materials in the industrial economy, make necessity of programming for shipment of hazardous materials more serious. This thesis, presents an optimiziation model for routing and scheduling for shipment of hazardous materials. This model is a multi criteria time varing mixed integer programming (MIP). The presented model, finds the optimal routs and scheduling of movement...
Network Pricing Using Path Flow Information
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
The toll pricing problem has been investigated in the literature for the cases of link, cordon, and facility (bridge, tunnel and etc.) pricing. Taking advantages of new technologies, nowadays it is possible to track the path of individual vehicles and collect the tolls by means of electronic devices. In this regard, we concerned the problem of path pricing. In this thesis, a variety of models for path pricing is proposed, the models are solved for the Hearn network and the results are compared to the results of link pricing models. In addition to the models, one exact solution method and two heuristic methods are proposed for the model of path pricing with the minimum total toll....
Comparing Meta-Heuristic Algorithms for Solving Transportation Network Design Problem
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Discrete network design problem is selecting a set of feasible projects among a set of candidate projects, considering a budget constraint in which user's cost is being minimized. Network design problem is one of the complicated problems in transportation science, since it is a bi-level problem in which the lower level is a traffic assignment problem and the upper level is finding the best set of arcs. Meta-heuristic algorithms can be used to solve this problem. Although, there is no guarantee to find the optimal solution by Meta-heuristic algorithms, but they find good solutions in short times. The purpose of this study is comparing the efficiency of three Meta-heuristic algorithms for...
Solving Traffic Assignment Problem with Side Constraints
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
In recent years, traffic assignment problem with side constraints has been considered because of the importance of transportation supply management. Side constraints which are appeared due to imposing the traffic control policies are usually represented in form of link, node or district capacity constraints. Although link capacity constraint has been extensively studied, only a few papers on the other types of constraints such as capacity constraint on inflow to a district of city exist in the literature. In this research a method based on dynamic penalty function (DPF) is presented to solve traffic assignment problem with side constraints. Solution algorithm has been coded in a programming...
Creating Bus Timetables with Maximum Synchronization
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Improving synchronization in a bus network has a profound effect on reducung waiting times and increasing satisfaction of system’s users. By doing so, the scheduler create a more attractive transit system that generates the opportunity for increasing the number of riders. In this research, the problem of creating timetables with maximum synchronization is modeled as a mixed integer programing (MIP) problem. The objective of this model is to minimize the total waiting times of passengers at transfer nodes. For this purpose, the model take advantage of uneven headways. Some of features that distinguish this research are more realistic objective function, and considering adjacent departures...
Solving Congestion Pricing and Network Design Problem Simultaneously for Conventional and Automated Vehicles
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
In this dissertation, transportation networks with two classes of vehicles, including conventional vehicles and autonomous vehicles, have been studied. Four problems, including traffic assignment problem with two classes, congestion pricing problem for conventional vehicles, network design problem for autonomous vehicles, and simultaneous congestion pricing and network design problem, have been modeled and algorithms to solve them are presented. In this study, a dynamic penalty function algorithm is used to solve the congestion pricing problem, and a heuristic algorithm is used to solve the network design problem. Besides, the two-class traffic assignment problem is solved using the...
Locating Gas Stations in Urban Areas
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Control and managing of fuel consumption is one of the most important issues facing man kind today. Locating gas stations has a great effect on fuel consumption. The gas station locating problem consists of selecting the optimal choice between the candidate nodes for constructing gas stations in such a way that minimizes the excess travel time that results from the gas station not being located on daily travel paths. The gas station locating model is presented for two conditions of either considering and not considering the gas station capacity. In the case of not considering the gas station capacity, a compact model is presented, too. Softwares for medium sized networks and the Simulated...
Applying Signal Coordination in Dynamic Traffic Assignment
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Signal Coordination is one of the appropriate methods for delay reduction in intersections. Static Traffic Assignment is unable to reflect the impacts of Signal Coordination in a network. One proper way to overcome this difficulty is to use Dynamic Traffic Assignment (DTA) that can model complex properties of traffic flow. This thesis presents a method to apply Signal Coordination in Cell Transmission Model. Neguin network is tested for different intersection's green start times. The results show that Signal Coordination has great influence on total travel time and route choice in this network. Finally, the results have been checked with AIMSUN NG, a microsimulator software.
Estimation of Origin-Destination Matrix from Traffic Counts and Cellphone Network Data (Case Study: Shiraz City)
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
The trip demand information in the form of the origin-destination (OD) matrix is of significant importance in the transportation studies. Obtaining such a matrix by conventional methods requires a considerable amount of time, cost, and human resources. Traffic count and cellphone network data are two relatively inexpensive data that can be used for estimation of OD matrices as well as correction of prior matrices. The trip demand estimation problem is a bi-level model, and the gradient algorithm is one way to solve it. This study, by generalizing the gradient algorithm, attempts to a better use of the available data. In this algorithm, a complementary algorithm is used to solve the traffic...
A Trip-Chain Based Traffic Assignment Model of Electric Vehicles
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
The goal of this research is to solve the traffic assignment of electric vehicles with considering trip chains. Limited driving range of electric vehicles is considered as one the most important obstacles for the development of these cars. The worry that the battery will run out of power before the destination is an important issue regarding the electric cars and people usually experience it more in trip chains. In this research, a complementary model and a linearization method is used for traffic assignment. In determining shortest paths in the traffic assignment, in addition to considering the travel time and the distance limit, the constraint of passing through activity nodes is...
Autonomous Vehicles Network Design To Improve Network Performance
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
Nowadays, with the advent of Autonomous Vehicles(AV), Researchers in different areas focused more on this type of vehicle. Research shows that autonomous vehicles are faster and more precise than Human-driven vehicles(HDV). So if all the users in a road use autonomous Vehicles, the road’s capacity increases; this Thesis develops a mathematical approach for designing AV exclusive lanes for a time horizon in which there are two types of AVs and HDVs on the road. Considering each type of vehicle’s relative performance for an OD pair in the given year, the demand for that OD pair for the next year calculates with a diffusion model. Designing AV exclusive lanes problem is formulated in a bi-level...
Design and Implementation of an Internet-Based Survey on Route Choice Characteristics
, M.Sc. Thesis Sharif University of Technology ; Zokaei Aashtiani, Hedayat (Supervisor)
Abstract
It is assumed in many traffic assignment models that people choose their path based on shortest travel time. Few empirical studies of revealed route characteristics have been reported in the literature. In this study, first, an innovative internet-based survey using Google map has been designed and implemented. The sample includes the people who commute to Sharif University of Technology in the morning peak hours. Next, observed routes in 134 valid questionnaires have been analyzed by using Tehran network database and VBA programming. Besides the length and travel time of each path, other characteristics of the observed route such as the number of right, left, and U-turns, number of...
Stochastic Traffic Assignment Based on Discrete Choice Models
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Accurate and realistic forecasts of traffic pattern in the networks can affect many decisions of urban transportation planning. In recent years, traffic assignment (TA) using stochastic models have received more attention by researchers of this field. Stochastic approach of route choice modeling using random utility theory has specifically developed to relax restrictive assumptions of traditional deterministic model and to address randomness nature of travelerʼs behavior. Together with development of discrete choice theory, more advanced models have been utilized to better represent route choice behavior. Although there have been considerable researches in the context of stochastic traffic...
Multi Modal Traffic Assignment with Mode Choice Models
, M.Sc. Thesis Sharif University of Technology ; Zakai Ashtiani, Hedayat (Supervisor)
Abstract
Traffic congestion is one of the most important issues facing modern societies that causes many impacts such as environmental pollutions and waste of physical and spiritual energies. One of the traffic congestion mitigation strategies is network management, which encompasses a diverse range of tools. Efficient management of urban transportation network requires the transportation network information. Traffic equilibrium in the transportation network is one of the fundamental information that is required for most of network management tools. In this study, a multi-modal traffic assignment model with complementarity structure is proposed that can determine the multi-modal traffic equilibrium...
An Approach for Solving CordonPricing Problem with Two Classes of Vehicles
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Nowadays the increasing congestion in transportation networks has made the managerial methods for controlling the congestion more important. Cordon pricing is one of the managerial means for reducing congestion. Therefore, accurate modeling methods that are consistent with reality and efficient traffic assignment algorithms play important roles in solving this problem. In this research several multiclass traffic assignment algorithms were examined and simultaneous complementarity algorithm was recognized to be able to yield equilibrium solution faster than other algorithms examined in this study. The aim of this thesis was also to analyze the effects of cordon pricing on networks with...
Nowadays the increasing congestion in transportation networks has made the managerial methods for controlling the congestion more important. Cordon pricing is one of the managerial means for reducing congestion. Therefore, accurate modeling methods that are consistent with reality and efficient traffic assignment algorithms play important roles in solving this problem. In this research several multiclass traffic assignment algorithms were examined and simultaneous complementarity algorithm was recognized to be able to yield equilibrium solution faster than other algorithms examined in this study. The aim of this thesis was also to analyze the effects of cordon pricing on networks with...
Optimal Deployment of Electric Vehicle Charging Stations
, M.Sc. Thesis Sharif University of Technology ; Zakaei Ashtiani, Hedayat (Supervisor)
Abstract
Limited oil resources, increasing rate of oil consumption, and environmental concerns related to burning fossil fuels promote the use of alternative fuel vehicles. Electric vehicles are common among alternative fuel vehicles which decrease greenhouse gases emission and fossil fuel dependence. To increase electric vehicle market share, some challenges need to be overcome including range anxiety. Limited driving range is one of the main challenges for battery-powered electric vehicles. The distance limit inevitably changes electric vehicle drivers’ travel behavior. Given the scarcity of charging stations, consumers perceive this driving range limit to be a potential worry. Therefore,...