فصلنامه مهندسی حمل و نقل
سال یازدهم شماره 2 (پیاپی 43، زمستان 1398)

The increasing rate of traffic congestion, air pollution especially in developing countries, in addition to, the decreasing levels of physical activity have motivated walking as a non-motorized mode choice to decision makers. The study aimed to explore predictors of influencing factors on walking time duration and its choice among individuals in daily trips. For this reason, logit and duration models have been applied. The data used in this study have been gathered for updating the comprehensive transportation plan of Mashhad. The results indicate that various variables such as larger household size, younger people, and higher residential density have a positive relationship with longer walking duration and higher share of walking trips among all daily trips. Findings also indicate that men and well-educated people walk more compared to the competing groups (women and low-educated people, respectively). The results for various groups of occupations show that in general, students tend to walk more than others. Provision of required infrastructures and setting incentive policies to encourage walking in governmental organizations and private firms can promote walking especially among employees.

In this paper, a new method for a vehicle routing problem (VRP) with reducing the fuel consumption and maximizing customers’ satisfaction. To reduce the hazardous effects of transportation like land usage, resource and energy consumption, air pollution, global warming, damage to ecosystems and human health, researchers developed optimization models like vehicle routing problem (VRP) and its variants. Generally, the amount of pollution emitted by a vehicle over an arc (i,j) depends on many factors like vehicle load, travel speed, travel distance, road slop and etc. Vehicle load has a major effect among other factors on amount of emissions and influences the route selection. On the other hand, this paper considers customers’ satisfaction via considering earliest and latest service time in customer nodes. It is proven that VRPs belong to the category of NP-Hard problems thus due to the complexity of VRP with exact methods in large-scale problems, a meta-heuristic method based on bee algorithm (BA) is proposed. Furthermore, to show the efficiency of the proposed BA, a number of test problems in small and large sizes are solved. Finally, the obtained results are evaluated with the results obtained by GAMS and PSO algorithm. On the other hand, this paper considers customers’ satisfaction via considering earliest and latest service time in customer nodes. It is proven that VRPs belong to the category of NP-Hard problems thus due to the complexity of VRP with exact methods in large-scale problems, a meta-heuristic method based on bee algorithm (BA) is proposed. Furthermore, to show the efficiency of the proposed BA, a number of test problems in small and large sizes are solved. Finally, the obtained results are evaluated with the results obtained by GAMS and PSO algorithm.

Railway superstructure availability is a clear precondition for presenting railway services. As public demands does not accept any interrupt in the planned railway services, superstructure failure prediction will be very important in maintenance. Among the superstructure elements, the track circuits with direct influence on track availability, has the most complex behavior to predict its failures. Recent literature has not provide any failure time estimation for general conditions of equipment specifications, maintenance and utilizations. Most of the research activity has been devoted to evaluating signaling system in a limited space of models for operational conditions. The basic predictive model is founded on the estimation of probability distribution and reliability functions over large number of real events with the validation of basic probability theorems on estimation and standard statistical test. Tehran railway station track circuits are selected as a general track circuit for the case study, to estimate its cumulative distribution function of failures by analyzing ten years experience of operation in past. The estimation is fitted on the Weibull distribution function to obtain the shape, scale and threshold parameters of the model. Experimental results indicates that the track circuit, with the mean time between failures as 2.7 days, is foreseen to operate correctly for the next 1.7, 7.5 and 11 days after starting with the probability of 50%, 10% and 5%, respectively.

Traffic accidents are a major cause of fatality in developing countries, especially Iran. Today, this issue has become one of the critical issues facing traffic engineers and transport planning managers. The human factor is the most influential in determining the level of road traffic safety, amongst the three types of environment, vehicle and human factors. The driver’s status including mental, moral and risk-taking conditions directly affects driving. These conditions are variable and rarely predictable and may lead to unsafe situations. The risk-taking level of drivers is an important human factor in driving, which affects traffic safety. In recent years, a study on drivers’ behavior based on personality traits using field observations and self-reporting questionnaires has contributed greatly to traffic safety research. This study investigates the level of driver’s anger in the traffic behavior within a sample of drivers in Tehran and its relationship with traffic safety and accidents, which has been rarely noticed. Correlation analysis shows a significant relationship between the drivers’ age and driving years and the level of anger and also between the driver’s level of anger and the conflicts in traffic accidents. A comparison of the results of the study with those of other countries indicates that the rate of anger among Iranian drivers is lower than that of Indian drivers and higher than that of European drivers.

Bus urban public transport is one of the most considered systems and the buses have received more attention because of their special privileges compared to other systems. In most cities, the bus system is responsible due to the lack of advanced transportation systems such as subways, trams, and light-rail. Due to the positive attributes and advantages of this system, the improvement of their capabilities needs planning and consulting with experts. In this paper, a linear programming model for optimizing the public bus transportation system is proposed to minimize the total cost of setting up the lines, maintenance costs and fuel consumption as well as minimizing the bus arrival times in order to increase the welfare of the passengers. The proposed model is simulated in GAMS software and the sensitivity analysis is performed over the parameters. Due to the time complexity of the proposed model, a hybrid meta-heuristic method based on the Ant Colony Optimization (ACO) and Particle Swarm Intelligence (PSO) name PS-ACO is also developed and simulated in Matlab for solving the proposed model. The computational results show that the fuel cost and distance between stations have the most effect on operational cost, and the time distance between the stations is the most effective parameter on the passenger's welfare. Besides, the number of the stations highly affects the model complexity and solution time.

Stone Mactic Asphalt (SMA) has been considered by road makers due to its many advantages. From the advantages of this asphalt is improving the rutting resistance of asphalt mixtures, reducing the growth of cracks, improving the slip resistance, reducing the noise pollution caused by vehicle traffic. In this study, SBR polymer (Styrene Butadine Rubber) was used to improve the functional properties of stone mastic asphalt mixtures. This polymer was used as solid polymer which was mixed to the bitumen and liquid polymer which was mixed directly to asphalt mixture. For this purpose, the Marshall tests, indirect tensile fatigue, Wheel track and moisture sensitivity tests were performed on SBR-modified SMA specimens. The results indicated that the use of mixed SBR polymer in bitumen had a positive effect on fatigue and rutting resistance of SMA mixtures. However, the polymer did not have any substantial effect on moisture sensitivity of SMA mixtures comparing to the control mixture.

One of the most important steps in conducting transportation studies or implementing transportation improvement actions is to determine the importance and priority of the city's transportation goals. In general, two types of targets can be defined in transportation studies: goals and objectives. This article seeks to provide a method for the prioritization of the transportation goals, in such a way that the opinion of all people (officials, operators and experts) related to the transportation issue is taken into account in this priority. In the proposed method, after receiving the opinion of all people about the scores and priority of each goal, an integrated prioritization from the general viewpoint will be achieved through a proposed parametric model. The proposed parametric model is built upon adapting the well-known Multi-Objective Parametric Optimization model. The idea had been that given the dispersion of the scores within different people, the dominance structure should also be considered in addition to the average relative scores of the goals. The proposed method has been applied to prioritize the transportation goals of the city of Mashhad. Results show that if the dispersion of scores is not considered (and one uses the Simple Additive Weighting method, which prioritize the goals just simply based on the average relative scores), it will be accompanied by a decision error. The results of this study indicate that the first three goals obtained from both simple weighting method and the proposed method are analogous in Mashhad, but the fourth priority are different.

According to the fact that one of the most significant reasons for pedestrian accidents in signalized intersections is the crossing violation of pedestrian, therefore, the evaluation and investigation of factors affecting pedestrian violations have always been a concern for traffic safety activists. The aim of this study was to evaluate the external factors affecting pedestrian violations, especially factors related to geometric design and traffic condition. The behavior of 1590 pedestrians was captured in 10 crosswalks of 6 intersections in Mashhad, and the effect of 15 unique variables on each pedestrian was evaluated. Binary Logistic Regression used for data analysis by using SPSS software. Finally, the variables of the number of pedestrians on the side, the number of violating pedestrians on the side, the waiting time, the gap of the vehicle, the length of the crosswalk, the width of the median and the time of the pedestrian light was found to be effective on the pedestrian decision to cross. The analysis shows that increasing number of pedestrians would reduce the probability of violation 20.7%. Moreover, if the number of violating escorting pedestrians increases, the probability of violation would increase 81.4%. The increase of one unit in “pedestrian’s waiting time”, “length of the crosswalk”, “width of median” would result in violation reduction of 13.2%, 18.5%, and 14.6%, respectively. On the other hand, an increase of one unit in “vehicles’ headway” and “duration of red light” would increase the violations 17.8% and 2.8%, respectively.

Finding new solutions to improve the resistance of cold mix asphalt mixture to moisture susceptibility and prevent damages resulting from penetration of water into the mixture is essential and inevitable. In this study, calcium carbonate sedimentation on the cold mix asphalt aggregates by a bacterial agent was employed to create a surface of CaCo3 sediment. This thin layer of CaCo3 makes the surface layer of aggregates hydrophobic and thus improves the bitumen coating and resistance to moisture damage of cold mix asphalt. Biological curing was carried out for 31 days on the aggregates retaining on #50 sieve. X-ray diffraction and Fourier-transform infrared spectroscopy were utilized to determine the formation of calcium carbonate precipitation on the surface of aggregates. The results of these two tests confirmed the formation of calcium carbonate precipitation. Then, two types of cold mix asphalt mixtures were prepared using conventional natural aggregates (CMA) and cured aggregate with the bacterial agent (B-CMA). The modified boiling water test was performed along with the image processing technique on the surface of aggregates to quantitatively investigate the effect of the bacterial agent on the moisture susceptibility. Moreover, the ultrasonic test was done to examine the stiffness and dynamic modulus of the cold asphalt mixtures. Furthermore, statistical t-test was performed at 95% confidence level to evaluate the effect of the bacterial agent sedimentation on the results. Findings revealed that B-CMA mixture has better coatings of aggregates by bitumen, less stripping in the modified boiling test, and higher dynamic modulus than CMA mixture.

Nowadays, transportation plays a major role in the political, economic, and social development processes. In this regard, railway industry is of higher priority over other transportation types due to various features including less fuel consumption, reduced environmental pollution, higher safety, less land use, and more passenger and commodity transfer rate. Therefore, focusing on its improvement and necessity of preventing the crises resulted from threatening grounds are among the inevitable requirements in this area [1, 2]. Since penetration of quicksands into railway tracks results in sand deposition on the tracks, track obstruction, train derailment, track flexibility damage, failure of railway fleet and electrical signs, and in fact leads to crisis, the present study is aimed to investigate the traditional and modern methods as well as an innovative method for reducing the penetration of sands into the tracks and reducing their accumulation on railway tracks. In addition to the currently existing solutions, the present study is focused on an approach for creating sand passage channels in embankments, modifying the hump-shaped geometrical form of the track sleepers, and providing an optimal channel design for easy movement of sands and leaving the sand passage path open for quick movement of the sands from the railway track area.

Attention to public transportation systems is becoming increasingly apparent as the advent of negative results of the use of personal vehicles. Therefore, the quantitative and qualitative development of Subway network in metropolises is considered as one of the main strategies in urban management. As the Subway network is expanded, it should also address the needs and expectations of people to increase the share of Subway network usage towards private cars by increasing people's satisfaction. Therefore, in this research, by analytical-interpretive method, the indicators of quality assessment and location of subway stations from domestic and foreign sources have been extracted and then a questionnaire based on the Likert spectrum is set. Then 150 questionnaires were completed with the help of the people at the subway station of Elmo Sanat. After that, data were analyzed by SPSS software and analyzed by factor analysis and linear regression model. The results show that the main factors explaining the quality of subway stations are respectively include "Accessibility", "Aesthetics", "Basic Welfare Facilities", "Positioning & Locating", "Secondary Welfare Facilities" and "Maintenance". Also, based on more detailed results, priority actions to increase people's satisfaction about the subway station of Elmo Sanat are related "Bicycle and motorcycle parking", "Wall paintings and graffiti" and "access and mobility of physical disability persons".

The adhesion between composite pavement layers plays a significant role in the long-term performance of these pavements. The purpose of this study is to investigate the effects of tack coats and their rate of usage on shear strength of interface between reinforced concrete and asphaltic pavements. In order to measure the adhesion properties, the direct shear test was used and also to measure the roughness of the surface of the concrete pavements containing the steel slag, the British pendulum and abrasion tests were applied in accordance with EN 1338. The results of the experiments indicated that the replacement of 50% of steel slag with aggregate caused an increase in mechanical properties and also in accordance with the abrasion standard of EN 1338 it was in appropriate range in terms of wearing. In addition, the results of the composite pavement shear strength test showed that with increasing the rate of tack coat application, the shear strength increased to reach the optimum point and then gradually decreased. The optimum rate of applying tack coat was varied from 0.6 to 0.9 liters per square meter depending on the type of tack coat. Considering the optimum rate of the shear strength ranking for different bitumen between composite layers was as follows: emulsion bitumen< control bitumen< crumb rubber with zeolite modified bitumen.

In the current century, the pattern of competition in production and services has shifted from competition among independent firms to competition among supply chains. Meanwhile, the issue of strategic design of the supply chain is one of the key issues in the field of supply chain management. In these issues, the aim is generally to provide a number of manufacturing facilities and distribution centers at the candidate sites (in different geometrical areas) in order to cover the demand for various products in the customer’s area. In the proposed model, demand for each product in customer areas is achieved through a number of distribution centers, while these distribution centers provide products from manufacturing factories, and these factories must purchase the requirement components to design and produce each product from suppliers. Here, a single-objective mathematical model of mix integer linear programming is proposed that simultaneously considers the facility location problem in addition to the design of the multi-level supply chain. In this model, there are various objectives, such as minimizing the costs of the procurement and production of components, the preparation and production of products, storage and dispatch the products to distribution centers, sending to customer areas and the cost of building factories and distribution centers. To evaluate the proposed model, the mathematical model is first coded with GAMS optimization software, and then solved for large-scale problems with particle swarm optimization algorithm and imperialist competitive algorithm. Statistical analysis of the results indicates the quality of the model and the proposed solving procedure.

In the study, the safety of students passing through the street by the slowdown of vehicles was examined. To this end, two plans were introduced as traffic tools near a school in Babol, Mazandaran province. The studies of before and after the speeds showed that the implementation of the cross-passage of pedestrians on the route (the first plan) resulted in a mean average speed of all vehicles of 3.66 mph, while the average speed reduction for the second plan "The school text" on the pavement (reported at a rate of 5.26 km / h). The rate of 85% reduction in all vehicles with the implementation of the first plan was 3.36 km / h, but the reduction of 6.86 km / h for the 85% speed of vehicles after the implementation of the second plan indicated the greater impact of the implementation of this plan. Also, the speed reduction rates differed from one gender to another. For male drivers, the average speed reduction after the first and second plans was respectively 3.97 and 5.27 km / h, respectively, while these figures were reported to be 3.78 and 6.21 km/ h for female drivers.