فصلنامه مهندسی حمل و نقل
سال یازدهم شماره 3 (پیاپی 44، بهار 1399)

The problem of air pollution and the deterioration of air quality in metropolitan cities is one of the most critical environmental issues in today's societies, which has caused serious risks to the health of humans and the surrounding environment. The flow of traffic in urban areas, which includes several fleets, has a significant contribution to the production of air pollutants in the city. The proper management of the various traffic fleets in the inter-city transit network can have a significant effect on the faster improvement of urban air quality during the air pollution crisis. In this study, a study was carried out on the analysis and modeling of the effect of traffic volume and traffic flow variation on the urban air pollution and pollutant concentrations near the air quality control station of the 11th district of Tehran. Hourly surveys were carried out under unheated weather conditions without atmospheric instability (including atmospheric precipitation, dust and drought phenomena, etc.). The results showed that, on average, when passing traffic equal to that of the various fleets in the study, passenger diesel vehicles compared to two diesel engine fleets and personal gasoline vehicles increased the impact of pollutants production PM2.5 and SO2. However, in the case of average traffic flow, the traffic flow volumes from the target range, on average, have a greater impact on the production of PM2.5 and SO2 pollutants than other fleets of the fleet.

The importance of maintenance of any system, with worn out components,  during operation, is  clear. Railway transportation system as a global and public system, requires permanent monitoring and maintenance. Because its reliability, safety and efficiency are highly dependent on the quality of the railway tracks. Due to the fact that the length of the railway tracks and the required maintenance volume are very high, the use of human resources to implement projects is uneconomic and virtually impossible. This is done by mechanized machinery used on railways. Because of the limited number of machines and the need to implement projects as many as possible, it is necessary to develop a heuristic technique capable to take both of the objectives and the priorities and requirements of the railway into account, at the same time. In this paper, the scheduling process of railway tracks maintenance operation in Iran Railways has been studied. A heuristic method has been designed and presented to schedule this operation. In order to see better the algorithm's capabilities, the results of the algorithm has been compared with the plan prepared by Iran Railways in 2017. To validate the algorithm, a simulation model has been developed. The results show that the algorithm can significantly increase the volume of scheduled operations. Providing a plan in a very short time and meeting all of the railway requirements and priorities are the other advantages of the proposed algorithm.

An intra-city rail transport system is a system in which a train ram travels at specified stations and in a direction between the origin and the destination. In this study, a model has been developed to minimize the operation cost of transport system. Hence an integer linear mathematical model was proposed for planning on four subway lines in Tehran out of seven existing lines and optimizing the number of wagons assigned to the lines that solved using WinQSB software. The purposes of this paper is to reduce the cost of the subway network, present a planned model to encourage individuals to use this type of transportation system, and thereby reduce traffic and air pollution in the metropolis of Tehran. To evaluate the proposed model, at first the present situation is compared with the results of the proposed model. The results showed that the proposed model would reduce the average costs incurred (electric power consumption and repair costs of wagons) by 33% in a month.

Abstract The most injuries of pedestrians happen when crossings, especially at mid-block crosswalk without traffic lights. Based on this, understanding the behavior of pedestrians and finding effective parameters during crossing can be very important from the point of view of safety. In this article, we tried to analyze pedestrian’s behavior in expose to vehicles, and determine effective factors in gap acceptance at mid-block crosswalk. For this purpose, filming was performed after identify suitable locations. By analyzing videos, effective variables were considered. After analyzing the data, the relationship between the characteristics of pedestrians by with their waiting time along the street to crossing was determined. Also attempts to safety pass and gap acceptance were presented in two models. In the waiting time model, the results showed that women had lower waiting time than men. By increasing  age, the waiting time also increases. The cautiousness of the pedestrian also increases the waiting time. In the gap acceptance model, which was obtained as a probability function by using logistic regression, the distance between the pedestrian to the approaching vehicle and following mode were influential variables on the probability of accepting the distance by pedestrians. The result was shown following pedestrians are more likely to accept the distance.

Rail transit has a vital role in city’s transport system’s efficiency. On the other hand, users’ satisfaction motivates them to remain as rail transit users. Encouraging residents to use rail transit ends in less pollution and congestion. This study investigates the role of service quality and perceived value on users’ satisfaction using a data set of 363 questionnaires filled by Tehran Metro users. Using a structural equation modeling reveals that there is no enough evidence to believe in gender differences in the structure and coefficients. The final model, using the whole sample, showed that users’ satisfaction is affected directly by perceived value (0.470) and service quality (0.349). Results reveal that these two factors explain 54.3% of the variance. It also shows that the measure of "the comparison with an ideal metro" is the best measure of satisfaction, the measure of "benefits against costs" is the best measure for perceived value and "the train and the station safety" is the best measure for service quality. These measures can be used as areas of improvement to achieve a better level of service in future.

Development of sustainable transport infrastructures or cultural program is one of important questions of policymakers in developing countries such as Iran. The present study aimed to answer this question by collecting data of environmental norms (norm-activation model) and built environment characteristics in an Iranian setting. More than 1000 forms were distributed among households in Rasht. Structural equation modeling (SEM) was used to test the hypothetical relationships between latent factors and sustainable mode choice. The model showed a good fit (Χ²/df=2.87, p< 0.001, RMSEA= 0.057, GFI= 0.90). Findings indicated where the regions lack safe and integrated sustainable infrastructure, cultural program is not an efficient policy for changing mode choice travel behavior. In these regions, development of sustainable transport modes is preferred policy for reducing car use. To increase the share of sustainable travel modes policymakers could facilitate walking and bicycling infrastructures. Furthermore, initiatives targeted to increase the accessibility level of households to public transportation may also hold promise.

Identifying the effective factors in traffic accidents in terms of transport safety is one of the basic issues that researchers have been focusing on for many years. A severe incident is a comprehensive result of several variables that causes accidents. The purpose of this study is to consider the effective factors on improving traffic safety and reducing motorcycle losses. Eighty five person selected from statistical population which included 200 person with experts in the field of accidents and safety and regulations. In this research, information was collected through a library study and the data was analyzed using the AHP technique and the Expert Choice software. This practical research has been conducted by designing a main question called "Effective components on improving traffic safety and reducing motorcycle losses". The results of this research, by introducing effective components, define the importance of each component for quantitative evaluation. Accordingly, the five main components of the effective factors on improving traffic safety and reducing motorcycle losses, together with their weight, are control of the skill of motorists, frequent education and information by the media, systematic planning to reduce intra-city travel citizens with motorcycles, judiciary intervention in the discussion of motorcycle driving violations and the strict implementation of motorcycle driving laws. he results of this paper can provide an appropriate perspective on designing a model for better understanding and preventing accidents from motorcycle accidents in the future by identifying the factors affecting the promotion of transport safety and reducing motorcycle losses.

The activity-based travel demand modeling is a disaggregate and behavioral approach which has been proposed for improvement of four stage models to improve the forecasts for the implementation of transport demand management policies and has been highly discussed in recent decades. The present study attempted to develop the activity-based travel demand modelling for Isfahan city which aims to have the ability of predicting components of daily activity schedule in disaggregate level and to consider interactions between daily activities and trips. For this purpose, the activity-base data structure was provided from comprehensive studies data of the city of Isfahan in1391. Using the obtained data, based on Boston's  activity based model, daily activity schedule decisions including the selection of the daily activity pattern, the main tour time of day, the main tour mode, the secondary tour time of day and the secondary tour mode were identified & modeled. Binary and multinomial logit models were used for this reason. Since the behavior of the mode choice of the primary and secondary tours were very similar, with Presentation the new structures for mode choice models, the behavior of the mode choice was modeled once generally for all tours and once again in separate intervals of tour performance. In this research, addition to previous research indexes, the model ability in prediction of correct choices has been noticed. Identified significant variables make clear understanding from activity and travel behavior of citizenry which can be used in transportation planning decisions. For instance, family kids, type of activity pattern, the out of town destination, job and gender of person, vehicle ownership etc. were Identified as affecting factors on tour mode choice.

Speed of the motor vehicles is one of the main risk factors in traffic safety, as it can increase both the chance and the severity of a crash.  In order to achieve an improved traffic safety  by  influencing  the  speed  of  travel,  road  authorities  may decide  to  lower  the  legally  imposed  speed  limits. In this study, information from speed cameras and traffic counters installed in Ghazvin-Rasht and Bam-Kerman interstate highway were used to explore the effectiveness of speed cameras in reducing the number of speed violations. Various methods of Before-after stufy, such as Empirical Bayes, and Comparison Group methods were employed to analyze the obtained information from the speed cameras installed in the studied highway. Results obtained from the Empirical Bayes method demonstrated 90 and 94% reduction in the number of speed violations at two of the studied locations. Comparison Group method also suggested 80-95% decrease in the number of speed violations at the two study locations. Overall, speed cameras proved to be effective tools in reducing the number of speed violations in these case studies.

Design of vertical alignment with minimum earthwork cost can effectively reduce the construction costs of highways. In most past researches, the objective function has been considered as the sum of the absolute value of difference between the vertical alignment and the existing ground and due to the complexity of earthwork calculation, real costs of earthwork have been ignored. Also, to deal with constraints just the static penalty functions are employed. In case of static penalty functions, if one of the constraints is violated, a relatively large coefficient is multiplied by the objective function and as a result, many early populations are removed in the next iteration and the convergence time increases. This paper aims to compare different penalty functions for problem of vertical alignment optimization. To this end, station, elevation and vertical curve length in case of each point of vertical intersection (PVI) were considered as decision variables. The objective function was considered as earthwork cost and constraints were assumed as the maximum and minimum longitudinal slope, minimum elevation of compulsory points, and the minimum length of vertical curves. For solving of this optimization problem, the accelerated particle swarm optimization (APSO) and the colliding bodies optimization (CBO) algorithm were employed. The results illustrate that the selected penalty function greatly affects the convergence speed as well as the optimum solution (earthwork costs). This study also showed that the effective optimization of highway vertical alignment can be achieved using annealing penalty function and CBO algorithm.

The main purpose of this paper is to investigate the effect of capacity on queue parameters, in order to improve the efficiency of the road by creating a proper change in the capacity of the highway and reducing the delay caused by queuing. As a system sends a parameter out of the output at a specified time interval, in other words, the system does not have the ability to service the entire input request, the queue is created and the vehicles must wait for service. In traffic queues, in addition to reducing the quality of the trip, Undesirable effect on traffic flow safety is also pronounced. The demand for the use of the road is variable throughout the day, and unfortunately there is no possibility of storing supplies in transportation. Consequently, in many periods of time, it is not possible to use capacity. It is possible to reduce the delay in the roadway by changing the capacity at different intervals. This involves sensitivity analysis on the effect of the capacity on the delay parameters. In this study, a definite queuing model is presented that can estimate the effect of changes in freeway bottleneck capacity on user delays. The formulation of the general problem is based on the definite queue theory and is solved by numerical analysis. A sample problem is investigated using a computer program. Finally, a sensitive analysis has been made on capacity changes. The results indicate that queue performance indicators improve with increasing capacity. By analyzing each case and performing such a sensitive analysis along with applying a suitable policy that changes the capacity of the way, the delay can be reduced and the route efficiency improved. Moreover, the proposed method helps to improve understanding the failure phenomenon in the upstream of traffic jams and large queuing models, and the sensitive analysis can be used to control traffic management. Using the proposed numerical method for each log entry and exit rate, one can calculate queuing parameters in each system (even non-traffic) and calculate the appropriate capacity with expected latency parameters.

Since there are different types of transportation modes and their corresponding time cost in cities, one way for minimizing transportation cost is finding the best transportation mod out. In this paper, the factors influencing the choice of trip mode in the framework of the polynomial logit model were investigated. 384 data were obtained by random sampling of intra-city trips to Azadi Square in winter of 2017 in Isfahan. The dependent variable (traveling mode selection) has four floors: personal car, regular bus, express bus and taxi.The personal car was selected as the reference class and the other classes were compared with the reference class. According to the results, in the Logit Model, between the reference alternative and the conventional bus, the cost variables, walking time and expectation of a negative relationship and lack of access to the fastest bus, personal ownership of the car and travel time have a positive relationship with the possibility of choosing a typical bus compared to the reference alternative. In the second Logit model, between the alternate reference and the taxi alternative, the travel time, walking time and expectations of the negative relationship and the cost and ownership variables are positively correlated with the probability of choosing a taxi mode than the reference alternative. In the Logit III model, there is a positive relationship between the alternate reference and the bus of the fast-moving travel time variables, the lack of ownership of the vehicle and access to the fast-moving bus, and the cost variables, walking time and waiting time are negatively related to the possibility of choosing a bus to the alternative than the reference. The results of clustering showed that clustering increased the prediction accuracy of the model relative to the ungrouped state.

Today, turbo and modern roundabouts are the effective commonly alternatives for controlling urban at-grade intersections which are used to improve traffic conditions and delays. Because of their geometric features in selecting way and the right of way for drivers, they have better efficiency than signalized intersections. In the beginning of this study, in order to evaluate the effectiveness of turbo and modern roundabouts in reducing traffic volume, increasing capacity and also examine traffic effective parameters (radius, lane number, speed and traffic flow)), Aimsun software  was used for simulating. And then by using Surface Response, Hessian Gradient Methods and Genetic Algorithm, a mathematical relation for estimating delay time in turbo and modern roundabouts in condition of non-traffic signal control was suggested. The obtained results from this research indicate that the mixed methods of surface response – Hessian gradient and surface response- genetic algorithm are more accurate than other methods. Therefore, the obtained delay logarithm relations according to the input variables (traffic flow, speed, lane number and radius) could predict delay in turbo and modern roundabouts with proper accuracy in non-traffic signal control conditions in which these relations have acceptable sensitivity accuracy.

Aging phenomenon affects pavement performance that results in reduced flexibility of the pavement. Aging can cause asphalt binder stiffness in asphalt mixes and increases the risk of cracking. Cracks can be healed by the induction heating method. The ability of asphalt binder in flowing and filling cracks plays a dominant role in the induced healing of asphalt mixes. With this regard, activated carbon (AC) is added to asphalt concrete in order to enhance the electromagnetic radiation absorption of mixes. In order to apply age conditioning, both the control and modified asphalt concrete samples were kept in oven for 5 days at 85℃. It was found that heating rate of activated carbon modified asphalt mixes is 55 percent greater than control mixes. From the results of this study, effects of asphalt concrete aging was determined by induced healing index. In addition, repeated breaking-healing cycles were applied through indirect tensile testing to investigate the induced healing properties of asphalt mixes. This was through peak load and fracture energy criteria. In addition, effect of sample dimensions on heating rate and damage level were investigated on induced healing index of asphalt concrete. It can be concluded that increased asphalt concrete aging and increased breaking-healing cycles resulted in decreased induced healing index. Result reveals that combination effects of aging and breaking healing cycles resulted in 48 percent reduction in healing index. In addition, testing results confirmed that AC as a conductive component has potential of induction heating healing and increasing aging resistance of asphalt mixes.