Sharif Digital Repository

Network design problem (NDP) is an important problem in transportation planning, in which transit network design is one the most important problems. Public transportation means, however, can not meet urban mobility needs in the developing countries satisfactorily. Bus services are usually unsuitable, insufficient, and unreliable. Bus Rapid Transit (BRT) system, is an emerging public transport alternative designed to provide appropriate, low cost, and effective services, and improve mobility in both developed and developing countries. To design public transportation systems, existing constraints such as resources and budget have to be considered to serve estimated demand properly. Bus Rapid... 

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... 

This study is an endeavor to model the interaction between transportation and land use, as a constituent of a joint land use-network design problem defined in the context of transit oriented development (TOD). Population and employment follow a Garin-Lowry model; the endogenously determined transportation demand is administered by a joint mode choice-assignment model; and mode choice is governed by a logit model. Equilibrium of population choice of place of residence, employment choice of place of retailing, and passenger choice of mode and path, are all governed by a maximum utility principle. An algorithm is devised to reach these equilibrium states by an evolutionary process, whose engine... 

Road construction and maintenance constitute a significant part of country-wide infrastructure development budget each year. This indicates the importance of planning and design of individual road alignment in reducing the development cost. This study presents a meta-heuristic algorithm based on the concept of electromagnetism, which explores and finds a good route between two given points within a three-dimensional (3-D) context. It defines the region in a continuous 3-D surface, identifies initial routes, which are directed and shaped toward better positions by the help of local and global search. The final good solution is fine-tuned to produce a better alignment. The behaviour of the... 

Traffic volume is the most important characteristic in most traffic studies, which is regularly measured by sampling methods for a given road. Traffic volume has determining effect in specifying network origin-destination demand, improvement of roads, traffic distributions over the network, improving road parameters, air pollution and in other aspects of flow in the network. There are many ways to measure traffic volume in different situations. However, most of them are expensive to implement and in cases which take a long time to do the survey, or the number of locations are excessive, the operation would not be cost-effective. In this research we investigate using macroscopic... 

Expansions of large urban areas, as well as increase in the rate of car ownership, has given rise to the urban traffic congestion. One of the major approach to cope with the congestion issue is named Transit Oriented Development (TOD), which will cause changes in trip departure times, route choice, mode choice, and trip destinations. TOD also affects the land use in long-run periods. The goal of this study is to clarify the long-term impacts of TOD on land use and find the appropriate transit projects in order to abate the drawbacks of changes in land us. Land use/ transportation has been the subject of many recent studies. One of the previous studies investigates land use and transportation... 

Natural disasters take many lives each year and leave many others homeless, thereby occupy governments to restore previous conditions rather than deal with progress. Iran has also a worrisome record of natural disasters, and the unpreparedness of the parties involved turn each of such event into a disaster. The purpose of this study is to estimate more accurately the outcomes of severe earthquakes, and show its effect on the decisions which are made to mitigate them. The losses are classified into three groups of immediate, short-run and long-run, which are then measured by some common quantities. Using the 2003 Bam Earthquake as a reference, these quantities are used to measure the... 

The purpose of this research is to provide a method for finding a “good” solution to the network design problem with less computational efforts, faster than the existing conventional methods of solving this problem. Network design problem is the problem of selecting a subset of projects from a set of alternative projects so that to optimize the objective function (e.g., the total travel time in the network) subject to the set of existing constraints (e.g., budget). Due to the combinatorial and non-convex nature of the problem, its solution could be very cumbersome and time-consuming. Various methods have been proposed to solve this problem efficiently, providing good solutions at high... 

Resiliency is, now, recognized as a vital characteristics of every urban transportation network. This is so, because transportation network is considered as a life-line in disastrous events, such as major earthquakes. In this respect, design of networks may be considered (1) before the incident, (2) after the incident for 72 hours, and (3) from this 72 hours on. From the point of view of (1), design of the network may be considered as strengthening important links under budget constraints to withstand the design incident, in order to be able to function properly (to help the affected people, to evacuate the populated area, etc.).Design of network based on the point of view of (2), the one... 

The abstract is the most important section of the thesis because many readers limit most of their reading to abstracts, saving in-depth reading for specific theses. It should give the reader a "preview" of what's to come. The abstract should emphasize new and important aspects of the study or observations. The purpose of the abstract is to allow researchers to decide whether or not to read the whole thesis. The abstract is what researchers read first to decide if the thesis is important, interesting, and it allows them to assess the relevance of a thesis to their own research, without having to read the entire thesis. Thus, it is crucial that the abstract both summarize succinctly the key... 

The purpose of this study is to model the long-term effects of taxes on different aspects of private cars upon auto ownership and use, and thereby auto industries in producing more fit cars, so as to minimize auto emission. It involves used car market, different car demands and auto industry production. The study follows some previous studies in this area and tries to enhance the various aspects of the model by directing it toward a more real situation. In order to visualize the effects of the model, it has been applied on the case of Shiraz in 1378. It has been shown that the model was able to reduce air pollution and fuel consumption by 90% and 50%, respectively, as compared to the “Do... 

This study is part of a bigger project which models Transit-Oriented-Development in deteriorated land use area in order to transfer the residents of the unsafe buildings to new apartments built by the Bus Rapid Transit system, and at the same time increase transit patronage. Residents in the deteriorated land use area (R) trade their land for equivalent value of the new apartment floor area, built by the Private Sector (P). P, in return receive the permission to build equivalent value of “commercial” floor area on the land freed from R. P Builds this new commercial area, Operates it for a life-time (30 to 50 years concession period) and then Transfers it to the City Government, thus a BOT... 

Air pollution is known as one of the most important problems of large cities. The main reason for such air pollution is the increase in using private vehicles. There are some solutions for controlling and reducing air pollution. One efficient way to achieve this goal is by imposing taxes on aspects of private vehicles. The purpose of this study is to investigate the effect of taxes on different aspects of private cars to reduce city air pollution, by (1) promoting users to purchase smaller and higher vehicle technology including electric cars, and drive less, and (2) forcing local car manufacturing companies by market demand mechanism to improve technology in their products. This study is a... 

Throughout history, natural and unnatural disasters have caused great financial and human losses to human beings. Although these incidents are sometimes unpredictable and inevitable, with proper management, the casualties can be reduced. To optimally manage disaster response operations, it is essential to understand people’s vehicular movements in chaotic situations. This can be achieved by examining previous earthquakes. In the post-earthquake conditions, as the network experiences sudden and heavy loading, not only the debris falling on the roads but also the traffic congestion caused by the scared people will cause the links to close, and this will disrupt the relief and rescue... 

Deteriorated old urban neighborhoods usually have no access to appropriate municipal services, and have small-sized buildings, densely populated areas, and earthquake-prone structures. Residents in these areas do not have the will and financial ability to renovate their aged properties. A questionnaire survey of the citizens living in the deteriorated areas of the City of Tehran showed that 80% of households do not have a positive monthly financial balance and cannot afford the cost of reconstructing their properties. Serious drawbacks of previous attempts to renovate deteriorated areas, including lack of adequate government funding, and adding to the dependence of local citizens on... 

Road network expansion is a well known problem in the world, particularly in developing countries. One approach in financing this development is to charge the users for the services rendered. Recent studies prove the merits of private sector participation in road investment and revenue collection. Public sector may cooprate with private sector in permitting it to build the roads, operate and maintain them for certain period of time, while taking advantage of the revenues collected. The road will, then, be transferred to the public sector when that period of time is over. This study presents an extension to a previous model in this area. It presents a bi-level programming network design... 

Data collected from street networks show that travel time in urban street networks is a stochastic variable, whose range of variation increases with the congestion level. Work and school trips comprise the major part of morning peak volumes, whose common characteristic is that they need to be made on time. For this reason, these travelers are pessimistic in their route choice, and try to choose routes which are more reliable. Travel time standard deviation is one of the common measures for estimating travel time reliability that is related to properties of day-to-day travel time distribution on a particular route. Based on the empirical data collected from Tehran street network, this paper... 

Chaotic Flow in transportation networks has been the subject of several studies. Evolutionary models have been employed to simulate traffic flows. This study takes advantage of an existing evolutionary model of traffic assignment to show that chaotic phenomena arise when the model’s driving force is speed or density, of traffic flow. It has been observed that drivers show higher sensitivity when the network is more loaded.

 

A large number of construction projects include repetitive projects. Many researchers have presented different methods (such as Non-Unit-Based method) for scheduling this class of projects in order to overcome the inabilities of network-based scheduling techniques. Despite the advantages of Non-Unit-Based method over others, it has failed to gain considerable attention. This paper aims to develop this method to enhance its efficiency in scheduling repetitive projects. The first objective of the paper is to develop Non-Unit-Based method in the following aspects :(1) scheduling the project based on the latest start time of crews in addition to the earliest start time of crews;(2) obtaining the...