فصلنامه مهندسی حمل و نقل
سال ششم شماره 2 (پیاپی 22، زمستان 1393)

Restricting passenger cars in congested urban areas is one of the conventional methods for pollution reduction and demand management. Although enforcement of plate number rationing scheme in Tehran (Even- Odd Zone) was in order to manage the traffic demand، this scheme is currently inappropriately controlled manually by police visual surveillance at the entrances. In this way، some problems such as low flexibility of policemen and a significant number of violations due to human error stress the necessity of using mechanized control for enforcement of plate number rationing zone. In this research، the authors have attempted to maximize violation detection by locating cameras at the entrances. The suggested model in this research is a binary model and covers various constraints such as budget constraints، staffing and minimal number of roads in a different road hierarchy. Because the number of streets that should be controlled by cameras is related to allocated budget، the sensitivity analysis of this budget is done and violation detection is presented. The results of sensitivity analysis indicate that violation detection would be increased significantly up to the approximate cost of 6. 55 trillion Rials. The results of this research and violation detection per different allocated cost would be an effective tool for authorities to allocate funds for this project.

Any substance that damages the people، equipment and the environment may be considered as hazardous material. Consequences of an accident during transport of hazardous materials can affect the human health and led to death or injury، environmental impact، traffic problems، etc. Increasing the transportation of these materials results the risk of increscent of accidents and damage caused by these accidents. Due to the last accidents occurred in this issue and unfortunately financial، environmental loss and above all life loss have been occurred، evaluation of the material transportation accidents is required. Considering that the most hazardous materials transportation takes place in roads، the purpose of this paper is the spatial assessment of road accidents caused by transportation of hazardous materials. Assessment of hazardous materials in road transportation accidents requires a range of data، statistical data، analysis، modeling and spatial decision-making at different levels of location. For this purpose، Geospatial Information System (GIS) can facilitate the process of problem solving by its instrument and competences. In this paper effects of toxic gases were evaluated. In the case of toxic gases the Gaussian or Heavy Gas model is used because its ability to consider the effects of wind speed and direction and atmospheric conditions.

Accident risk equal to the number of accidents for a given exposure index is an appropriate measure to evaluate the effects of various factors on the occurrence of the accident. The main exposure index used to calculate accident risk، vehicle- kilometers are traveled. The main problem of vehicle-kilometers covered by this lack of information، especially when exposed to a specific group of users of the transport system (eg young drivers) or special circumstances (e. g. during the night) is to be doubled. The researchers therefore indirect measures of exposure such as the induced and the quasi-induced exposure to solve this problem have been proposed. In this studyinfluence of human factor (age) and environmental factors، including location (urban، rural)، site geometry (straight، curve horizontal) and lighting (day، night)، in risk of motorcycle driver at-fault in accident investigated. the Method was based on concept of quasi-induced exposure that based on innocent drivers /riders in two-vehicle accident with one-fault and one non-fault can be considered as a sample of the total population of drivers in time of accident. Data related to traffic accidents in 1390 in Iran which a total of 39،014 samples for analysis were. The results show that probability of at-fault younger and older drivers are more than middle-aged drivers and environmental factors، including rural (RR=1. 25، Sig<. 006)، curve (RR=1. 31، Sig<. 012) and day (RR=1. 12، Sig<. 026) increase probability of at-fault motorcycle drivers. Also effects of environmental factor on young drivers are most of the other drivers and lighting effect in urban and direct routes are less than rural routes and horizontal curves. Finally construction special routes in rural routes for motorcycle،more monitoring in inspection of the motorcycle lighting system، practical training in increasing skills and education of drivers about the dangers of motorcycle to reduce risk of motorcycle accidents are suggested.

Planning and operation improvement of urban bus systems are closely tied to the ability to measure the spatial and temporal performance of it. Since the subject of urban bus system is public، paying attention to their needs and expectation plays a vital role in its performance success، also encourage them to use bus service. The main challenge of public participation in measuring performance of public transportation is the lack of an integrated infrastructure and subsequent inability to collect adequate and timely data. Recent promotions in Web2. 0، social networks and location-aware technologies such as the global positioning system، mobile-phone tracking، and Wi-Fi positioning system create new forms of the geo-collaboration for public. Volunteer geographic information (VGI) can be easily and quickly produced and shared in a dynamic، interactive، multimedia and distributed environment by users of different knowledge levels. Noting that urban bus system is considered as one of the most frequent modes of public transportation، in this paper a system is developed by using the advantages of Web2. 0 technology، volunteer geographic information and geo-tagging based on three-tire architecture to facilitate public participation in bus performance measurement. The system provides useful and updated information about bus lines، positions of stations and time-table schedules. Moreover، such a system is capable to collect different data types including quantitative، qualitative، spatial، and multi-media by stakeholders (current and potential passengers، professionals and employees) in any space and time consuming less time and cost. Then، by utilizing TOPSIS method، the performance of each line is calculated. The final result is presented using geo-visualization technique and Google­map­API. In this paper five bus lines in Tehran Municipality Region 4، are examined. Results of performance evaluation showed that Shahrak – e -Pars– Resalat­ Square has the highest performance rate.

In this study، the train scheduling problem in double track railway lines with makespan criteria is investigated. In order to maximize the use of railway capacity، trains should be scheduled as close as possible، subject to safety and operational constraints. An integer programming model is presented for maximize the use of existing capacity of a railway line. The main decision variables are the sequence of dispatches from origin station، headway time between successive trains، assignment of trains to tracks in stations and stop schedule for praying services in order to minimize the makespan criteria. Trains travel the railway line in the same direction with no permission to overtake. Stopping schedule of trains for performing praying services is unknown and should be determined as decision variables، but other services such as passenger load and unloading، refueling and water supplying are predetermined operations. The capacity of station is considered by the number of tracks and platforms existed for stop and pass of trains in the mathematical model. Some valid inequalities are developed to decrease the computational time. The performance of the integer programming model is tested on small، medium and large size randomly generated problems and two real cases of IRAN railway network. The output results show the effectiveness of the proposed valid inequality in reducing the CPU time for solving the small and medium size problems by CPLEX. The CPLEX can also solve the real size problems in reasonable time when the sequence of dispatch is known.

The main objective of this research is to analyze the fatigue life and resistance against fatigue cracks of asphalt mixtures modified by nanosilica at intermediate temperatures. In this research،4 % and 6 % nanosilica (by weight of base binder) was added to binder. We made use of resilient modulus، indirect tensile strength and 4-point bending beam fatigue experiments to evaluate the modified asphalt mixture resistance and fatigue life. The results showed that the nanosilica modified asphalt binder significantly improved the fatigues life and the resistance of the asphalt mixture against fatigue cracks at intermediate temperatures. Adding nanosilica led to a significant increase in the indirect tensile strength and resilient modulus. The results of the 4-point bending beam fatigue test showed that the addition of nanosilica increased the fatigue life of the asphalt mixture. Therefore، it can be safely stated that adding nano-silica reduces fatigue cracks، and increases fatigue life and resistance of asphalt mixtures at intermediate temperatures.

Cities are designed and built by human for human. Different components of a city، such as buildings and roads are all designed and built purposefully. Horizontal and vertical expansion of today’s cities is a necessity which has brought motorization and automobile dependence and consequently the expansion of roads became a requirement and not a choice. But cities can only be sustainable and viable if there is a balance in infrastructures and uses. Traditional and common thoughts based on demand can no longer be an appropriate answer to providing accessibility and human needs in the cities. That is why cities may be turned into parking lots and lose their efficiency and quality. One of the important impacts of automobile dependency is expose of cars on the city spaces. In other words، the city becomes a car-oriented city، where people are at the service of cars، not cars at the service of people. Modern ideas and plans are trying to make the city and transportation more and more human-oriented. One of these plans in the area of urban and transportation planning is called “Complete Street”. The complete street plan is a strategy which can simultaneously provide neighborhoods with safety، convenience and easy accessibility for pedestrians، bikers، drivers of public transport and the drivers. This paper is intended to first introduce the concept of complete street، and then to study the feasibility of implementing the plan in Iranzamain street، a street in Shahrak-e Qods in north east of Tehran. Research method in this project is both qualitative and quantitative. The analysis of the quantitative data is done by using SPSS software. Three different designs of turning the street into a complete street are introduced and the best design based on the scores of sustainable development is chosen. Findings show that Iranzamin Street has the appropriate capacity to become a “complete street” according to the sustainable development criteria.

60 percent of motorcyclist fatalities in traffic accidents of Iran are due to head injuries. Using motorcycle safety helmet is the main solution to prevent probable head injuries of motorcycle riders. Although، helmet-use law approved in Iran 12 years ago، the prevalence of helmet-use among motorcyclists remains low. This study investigates factors associated with helmet-use among motorcycle riders of Mashhad city based on data collected through face-to-face interviews. Confirmatory factor analysis was used for data reduction and identification of behavioral factors. Ordered and multinomial logit were applied to statistically describe helmet-use as a non-deterministic behavior. According to the statements of motorcyclists، rate of helmet-use is 47 percent، but in 14 percent of cases helmets were not used properly. In addition، 5 percent of motorcyclists believed in malicious impact of helmets on their safety. Norms، attitude toward helmet-use، risky traffic behavior and awareness of traffic rules were found to be the key determinants of helmet-use، while no appropriate significance was found for perception of enforcement strictness. Duration of daily trips with motorcycle، riding experience and type of job were affecting helmet-use. Results indicate that training and cultural programs to improve social norms and attitudes toward the use of motorcycle helmets beside effective law enforcement techniques possibly increase proper use of helmets between Iranian motorcyclists. In addition، special safety courses should be approved for motorcyclists who have committed traffic violations.

Thermite welding is a chemically reaction welding process. The weld joint is produced by pouring of superheated molten metal around the joint to be welded، applying with or without of pressure. the importance of mechanical properties and microstructure of thermite welded components، this paper studies the effects of Mn (it is one of the available choices to improve mechanical properties of steels microstructure) on mechanicaland metallurgical properties (hardness، impact resistance، tensile strength، elongation and wear resistance) of St49 steel in thermite welding process. The results show that with the increases of Mn in welded metal، tensile strength and impact resistance are increased but when the Mn content exceeds a certain level (% 2. 5)، the characteristic values ​​of the welded metal is reduced. Also، results show that with the increases of Mn wear resistance and the hardness of the welded metal were increased and the highest hardness in the railhead is 700 (Bhn) and in of rail web is 600 (Bhn).

One of the major problems caused by construction and demolition of buildings and highways is the environmental pollution due to the produced waste materials. Therefore، in addition to the protection of environment، the recycling and reusing of the waste materials is an economical measure. One of the applications of the waste materials is for highway construction. In order to investigate the applicability of the waste materials in pavement structure، as base or subbase layer، in this research، the compaction and mechanical properties of recycled asphalt and concrete stabilized by cement and reinforced by steel fibers have been studied. Different combinations of the recycled concrete and asphalt have been stabilized by various cement and steel fiber contents، and the compaction properties and the compressive and bending strength have been investigated. The results show that، in all the combinations، the optimum moisture content and the maximum dry density increase with increasing the cement content. In addition، it is found that، up to 9% of cement content، the compressive strength increases with increasing the cement content، and beyond that، the compressive strength decreases with increasing the cement content. Also، the compressive strength of the mixtures increases by addition of steel fiber، with the highest compressive strength at 1% of fiber content. The results also show that، the bending strength of the mixtures increases by increasing the cement and steel fiber content.

A Multi-depot Heterogeneous Vehicle Routing Problem with Time Windows (MDHVRPTW) is a variant of the Vehicle Routing Problem (VRP)، in which the vehicles do not necessarily have the same capacity and they belong to different depots. Therefore، the MDHVRPTW involves designing a set of vehicle routes، each starting and ending at the depot، for a heterogeneous fleet of vehicles which services a set of customers with known demands. Most problems presented in this field are single-objective problems with the aim of minimizing the cost; however، the complexity of real problems usually doubts the use of single-objective problems. This paper considers not only the minimum travel cost، but also the distance travelled by the used vehicles and their loads. Since this problem is NP-hardness، the use of a meta-heuristic algorithm is obligatory. Therefore a meta-heuristic algorithm based on Multi-Objective Differential Evolution (MODE) is proposed. In addition، to show the efficiency of the proposed MODE، a number of test problems in small and large sizes are considered and then solved. The associated results are evaluated with the results obtained by the ε-constraint method and results showed that the gained function gap was less than 3. 5% in all the solved problems. Furthermore، to run the proposed MODE، a real-case study in an oil distribution company is carried out. Finally، the obtained results are reported and discussed.

Today، cities as a place for human life and activities are faced with serious challenges in providing human needs. Population growth، increasing vehicle ownership and development of communication has caused increasing complexity of the transportation system and its consequent problems such as congestion، pollution and consumption of nonrenewable energy resources. Due to the unique benefits and advantages of cycling as a mode of urban transportation، and its role as a transportation demand management strategy، this simple، cheap and pollutant-free non-motorized vehicle has become of crucial importance. Previous studies have shown that changes in supply level are impressive on passengers changing modes and selecting cycling. Most such studies are based on logit model and structure and little attention has been paid to categorizing these supply factors. This paper analyzes the supply level impacts on cycling in work and study trips، based on factor analysis techniques. Supply level factors on cycling demand are determined based on a field survey of 608 Tehran citizens in municipality district number eight for work and study trips. Results of maximum likelihood factor analysis classify the variables into two categories: improved bicycle facilities and changing travel conditions. Results indicate، the greatest impact on work trips is changing travel conditions، while the key factor influencing study trips is improving cycling facilities.

Among the concrete bridge deck sections، single-cell box girder is one of the most common sections. Single box arrangements are efficient for both longitudinal and transverse designs، and they produce an economic solution for most medium and long span bridges. Design of prestressed concrete bridges involves many variables which are related to each other. So it leads to a wide variety of acceptable designs. Since bridge designers conventionally use trial and error method along their experiences، optimality of the design depends significantly on designers'' experiences. Thus these structures have significant potential of cost optimization. In this study، optimization of simply supported، post-tensioned prestressed concrete box girder bridges using Genetic Algorithm (GA) is presented. Genetic algorithm is an iterative procedure maintaining a population of structures that are candidate solutions to specific domain challenges. During each temporal increment (called a generation)، the structures in the current population are rated for their effectiveness as domain solutions، and on the basis of these evaluations، a new population of candidate solutions is formed using specific genetic operators such as reproduction، crossover، and mutation. They efficiently exploit historical information to speculate on new search points with expected improved performance. Iran bridge loading code is considered for loading the bridge and AASHTO standard specifications for highway bridges are used for designing the bridge. Various variables considered are cross-sectional dimensions of the girder، number of tendons، number of strands per tendon، tendons arrangement، reinforcements of slabs and prestressing force. Constant design parameters are bridge width، span length and material properties. It is concluded that optimization using new algorithms like GA is an appropriate alternative for traditional bridge design process which will result in saving in time، cost and human effort.