Sharif Digital Repository

Natural disasters claim major losses in human lives and belongings, as well as national infrastructures. Taking major earthquake as an example, the study has considered two sides of the problem, both before and after the incident. The former side is formulated as a multipartite optimization problem, in which each party’s activities are directed toward the long-term solution of the original problem. A heuristic method to solve the multipartite problem, and solve three example problems to show the applicability of the method was proposed. The solutions of example problems show that a directed problem solution reaches a better solution (in terms of the objective function value) than the... 

Congestion is the inseparable part of everyday life in large transportation networks. Expansion of road networks especially in downtown area is next to impossible and it is resulting multiplicative congestion problems. Congestion imposes private and public costs. Therefore, restricting policies on road use through cordon-based or area-based pricing is proposed to reduce the negative impacts of traffic, travel demand management and optimal use of transportation systems. This would produce better resource allocation through transportation network optimization. Implementation of congestion pricing policies induces short-term and long-term effects. In this thesis, it is attempted to determine... 

This research deals with pricing private automobiles entering a congested area in urban CBD to reduce auto-related air pollution. There are two factors affecting the pollution level: car volumes, and the weather condition. A Markov decision process is employed to find the optimal tolls and determine the prices for different states of the system, under several weather conditions. The demand for travel is elastic. It is assumed that users change modes in the short run. In longer terms, the part of the demand with shopping, recreation, or similar flexible trip purposes change the respective demand levels according to the price level. The study attempts to estimate elastic demand functions for... 

Traffic assignment model, as the last step to the well-known four-step planning models, have been under a special research focus to better capture the uncertainty in the decision-making process of the users. Researchers' use of fuzzy cost for travel time and stochastic assignment models have each aimed at considering the variation in perception of users and uncertainty in their route choices. This thesis has proposed two route-based stochastic assignment models that exploit the fuzzy theory to model network users' perception of travel time and stochastic assignment to model their route choice process. A simulation approach has been exploited to generate the routes prior to the assignment... 

Travel time estimation is a central issue in the urban transportation industry and is the basis of many analyses and services in businesses related to this area. In the past few years, various statistical approaches have been devised to solve this problem. The purpose of this dissertation is to review existing methods by focusing on segment-based approaches for urban travel time estimation. A big challenge is the small amount of data in hand compared to the size of the urban network. Exploring historical data and extracting correlation between urban network segments leads to modeling the urban traffic condition and travel time estimation in one specific time interval of the day  

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... 

Nowadays more than half of the world’s population lived in urban areas. That proportion is set to rise to 67% by 2050. This will cause urban mobility with serious problems. The concept of Urban Air Mobility (UAM) is proposed to avoid the problem to become a catastrophy. Due to environmental issues and also high operating costs, using copters as an air-taxi was not justifiable. As the technology in e-VTOL flourished, the desire of using of these vehicles in such a transportation system was increased. In this paper, besides previous investigations, the e-VTOL’s performance parameters’ influence on the characteristic of a civil air-taxi network is under investigation. In addition, this paper... 

Because of severe weather events (such as floods and storms), transportation infrastructures are directly and indirectly damaged, which may cause many undesirable economic and social losses for people and cities. Among various severe events, flood is known as an important factor in the breakdown (closure of roads and bridges) of the components of the transportation network. Evaluating the performance of the city's road transport network against flood events leads to a better understanding of the network's condition and allows decision-makers to identify the weaknesses in the system and reduce potential damages as much as possible. In this research, with the aim of investigating the... 

Transportation Network Companies (TNC) like Snap and Tap30 are ride sharing platforms that connect drivers and passengers in real time using simple mobile phone applications. The most interesting feature of these platforms is that they do not hire drivers and allow them to choose when and where to offer a ride. Dynamic and fluctuating supply and demand, the necessity to forecast the changes, implementing them in ride pricing and driver-passenger assessment are considered as important challenges for such systems. In this research, first, we want to analyze the spatial structure of TNCs and then forecast network changes more precisely. The method used for forecasting is LASSO which is a... 

Cloud manufacturing (CMfg) as an emerging service–oriented manufacturing paradigm integrates and manages geographically distributed manufacturing resources such that complex and highly customized manufacturing tasks can be performed cooperatively. In this study, a prospective conceptual model for CMfg was developed which can overcome or mitigate the issues and risks associated with supply chain processes on a global scale. Morever, three important problems in CMfg were investigated in this work: 1) Service Composition and Optimal Selection (SCOS), 2) Service Selection Optimization and Scheduling (SSOS), and 3) Sustainable Service Selection and Scheduling (4S). We proposed a new mixed–integer... 

Origin-destination (OD) matrix is one of the most important sources of information used in planning and management of transportation networks. Estimation of a precise OD matrix is a fundamental component for enabling the administrative authorities to optimize the use of their transportation network. Traditionally, urban planners use direct approaches including household questionnaires to estimate OD matrices. These methods are time-consuming and costly. Strategies that are more recent like Bluetooth, Wi-Fi, and RFID scanners and detectors include deficient precision and the additional cost of accessories. Exploiting GPS technology in spite of its high locating accuracy, due to user... 

The road authorities of a city have the responsibility of constantly assessing how well their city performs when traffic conditions are taken into account. In many metropolises around the world, if not taken preventive measures, there will be observed a density above the network capacity and a noticeable decrease in the level of service, especially in the morning and evening peak hours. Also, the dynamic congestion pricing of certain areas based on the traffic condition has always been considered significant by urban planning officials. Since this is not possible except by constantly assessing the current traffic state, a variety of methods have been used to predict the future traffic...