فصلنامه مهندسی حمل و نقل
سال سیزدهم شماره 2 (پیاپی 51، زمستان 1400)

The issue of transportation is one of the issues that has always been an integral part of the country's macro and strategic plans due to its connection with the country's macroeconomic and social infrastructure and the interaction between them. Examining and analyzing the opinions of those involved and stakeholders in the field of road transport for policy-making in this sector is the most important indicator of external road transport evaluation, which shows important issues such as evaluating delays and the impact of travel time on system utility. The study method is the design of a questionnaire, although part of it is apparently a pairwise comparison questionnaire (fuzzy AHP), but in the initial layer, the classification of variables of this questionnaire has been done with the help of rotating analysis included, which is a new method. In the first part, the inquiries from the passengers were made directly in the terminals of the west, east, south and Beyhaqi of Tehran due to the restrictions in four consecutive days and in the other twenty selected terminals with the help of local representatives. The system is optimized and improved with the help of suggested solutions. The most important results obtained from weighting are the indicators that have been considered for evaluation and pairwise comparisons; Dynamics of incentive policies (categories 1-0.27); System traffic performance (category 2-0.26); Safety (categories 2-0.39), welfare services (categories 1-0.21) and intelligent systems (categories 2-0.16). Therefore, from the results of weighting, it can be seen that the dynamics of incentive policies and policy types can with a high coefficient of micro and macro indicators to increase the share of public road transport and also focus the users' proposed solutions to increase the share of transportation. The general approach has been to policy-making, optimizing travel time, increasing the level of safety and quality of services that interact with the comparison method. Priority is given to the implementation of infrastructure projects in the field of public road transport, development of intra-terminal and in-terminal welfare services complexes, development and modernization of intelligent transport infrastructure, and acceleration of fleet modernization.

Qualification and assessment of job competencies of drivers increase productivity and reduce the rate of bus accidents. Among the important benefits of pre-employment qualification is the increased level of job compatibility of urban bus drivers. This paper aims to design a competency model for urban bus drivers in Tehran. The research method is quantitative and applied in terms of purpose. The statistical population includes 2000 private-sector drivers of urban buses in Tehran. The quantitative sampling method is simple random due to the homogeneity of the statistical population. The relevant questionnaire was distributed through probability sampling based on Cochran’s equation among 321 drivers. The results were obtained by analyzing data through confirmatory factor analysis using the factor loading rotated matrix. The weight factors for the the codes were calculated between 0.702 and 0.990 and for the categories between 0.841 and 0.980. The results confirmed all the seven dimensions, which had been obtained previously from the qualitative grounded theory through in-depth and semi-structured interviews with experts. These dimensions include general competencies, physical health, psychological health, driving knowledge, driving skills, communication skills, and cognitive ability.

In this study, the waste polybutadiene rubber was used for the first time to improve the bitumen performance at intermediate  and low temperatures. The 85/100 bitumen samples were prepared using a high-shear mixer with 1, 2, 2.3, 3, 4 and 5% polymer. The rotational viscometer, softening point, penetration and ductility tests were first performed on the polymeric bitumen. The initial results of the study showed that polybutadiene rubber increases the viscosity and softening point and increases  the penetration index. In the ductility test, by increasing the amount of polymer, the cohision property of modified bitumen is decreased, and for the percentages greater than 2.3%, the ductility level is less than 100 cm. Therefore, the 2.3% level was selected as the maximum amount of polybutadiene rubber in the subsequent tests. Then, the dynamic shear rheometer test at the medium temperatures and the bending beam rheometer test at low temperatures were conducted on the modified bitumen sample for the 1, 2 and 2.3% polymer. The results of the study showed that this polymer improves the bitumen performance at the medium and low temperatures and can improve the low bitumen temperature up to 1°. In order to evaluate the role of this polymer in the asphalt mixture, the semi-circular bending test was performed at low temperature. The results of the asphalt mixture test showed that polybutadiene rubber at 2.3 wt% of bitumen increases the fracture toughness by 65% at -10 °C.

In the past decades, many researchers have tried to improve the properties of bitumen and use such bitumen in asphalt mixtures. Adding rubber powder to bitumen and producing rubber asphalt creates desirable properties for the asphalt mixture, which will be a step towards moving towards sustainable development and environmental protection. The main disadvantage of this type of asphalt mix is ​​the increase in mixing temperatures and density, thereby increasing construction costs and difficulty of execution. In this research, the effect of semi-hot paraffin additive on reducing the mixing temperature of rubber asphalts has been investigated. Bitumen was mixed with two different percentages of 8 and 16 percent of rubber powder and modified with three different percentages of 1, 2 and 3 percent by weight of paraffin additive asphalt mixture. Also, samples of asphalt mixture were prepared and then compacted at two mixing temperatures of 130 and 150 degrees by Marshall method. To evaluate the performance of the asphalt samples, Marshall tests (strength and fluidity), dynamic creep and resilience modulus were performed. The results of modulus test showed that by adding rubber powder to asphalt mixtures as well as increasing the fiber modulus, the modulus increases. The results of dynamic creep test also showed that at a mixing temperature of 150 °C the furrowing resistance was better than the control samples. However, at a mixing temperature of 130 °C, the grooving resistance is reduced. The results also showed that increasing the percentage of parafiber improves the corrosion resistance of rubber asphalts.

Allocating the largest share of waste management costs to the collection sector on the one hand, and the necessity for operational efficiency of this system by reducing the spent time on the other hand, highlights the importance of optimization of waste collection and transport system as a principle in waste design and management. The importance of this issue is that even little improvement in the collection system could have a considerable impact on reducing total costs. Therefore, in order to develop a management system for (fleet collection and transportation), this paper presents an appropriate model for vehicles (truck) routing that determines the appropriate truck route, timetable, starting point, destination, and routes of each truck. The main innovation of this paper is the application of WebGIS and the development of optimal routing for waste collection vehicles with an emphasis on spatial parameters and features. To obtain an appropriate answer, routing vehicles with limited waste collection capacity were used in order to minimize the travel time and consider limiting parameters including, 1- maximum total allowable travel time and 2 – maximum allowable covered distance of vehicles. With the aim of optimal management of waste collection, features such as the amount of waste in each trash bin, the amount of time required to discharge each trash bin, the direction of network traffic, vehicle operating hours, road speed limits, time impedance and distance impedance of each edge were considered. The results show that in comparison to the current fleet, the proposed approach reduces travel time, distance, and fuel consumption by 14%, 24%, and 35%, respectively. User satisfaction with the WebGIS was also assessed indicating that 89% of the users are satisfied with this system.

Bus dwell times on urban bus operations play a critical role in correct scheduling and punctuality. Dwell time, since it is the amount of time at which boarding and alighting processes are performed, can account for the vast majority of the total travel time. Under peak load conditions, dwell time can experience a remarkable rise due to the friction existing between on-board passengers. The purpose of this study is to provide a number of strategies which are able to reduce the amount of dwell time. To do this, the previous studies in which the dwell time has been modeled by taking account of on-board crowding are investigated. Moreover, the present study simulates the flow of passengers by means of simulation tools to determine the optimal bus layout, including the optimal number of doors and their width. Being able to predict how a bus design affects passenger flow would consequently be highly valuable during bus development. The results show that the increase in bus doors can lead to a sharp decline by 37.6 percent in dwell time over considering three scenarios. Furthermore, increasing the width of doors and improving boarding policy can reduce bus dwell time.

In recent years, the extension of cities and cars has led to some crises such as increased fuel consumption, air pollution and urban traffic. Often a significant amount of vehicle energy is wasted as a result of sequential braking in high-traffic cities. Thus, the recovery and reuse of braking energy reduces fuel consumption and reduces air pollution. In this paper, we have estimated the average amount of energy and power lost in automobiles in Tehran due to braking in front of traffic lights according to statistics of 2014 and then have calculated the daily amount of energy that can be recycled. Comparing the recoverable energy from these brakes with the daily energy produced by the Parand power plant and the electricity consumption of the houses shows that only this type of braking can save 3% of the energy produced by the Parand power plant, which is equivalent to the electricity consumption of 96,000 residential houses. He searched. The results of the calculations can significantly tempt and justify the design and use of energy regenerative braking systems.

Walking between school and home is a good opportunity for students to reach the recommended level of physical activity during the day. The paper aims to investigate the effect of individual and family factors on the walking of primary school students to school. The study students (n: 1503) were randomly selected from 18 primary schools in Shiraz. The questionnaire included the student's travel type, their individual characteristics (age and gender), family characteristics (parental occupation and education, average income and so on) were completed and analyzed using the binary logistic regression model. Findings showed girls have less tendency to walk. In addition, increasing the father's level of education reduces walking among students. Moreover, an increase in the number of children in the family, having active daily trips by mothers and Improving parents' attitudes toward the quality of passages will increase students walking to school. Meanwhile, car ownership, the number of family members with driving licenses, average income, and parental attitudes toward traffic accidents and parental perception toward the walking time to school were indirectly related to a student walking. The present study highlights the importance of individual and family factors on students' walking rates for urban planners and policymakers. One of the important results of this study is that by changing the pattern of mother daily trips from personal vehicles to active trips, students will be more likely to walk to school.

Nowadays, it is necessary to understand the factors affecting accidents, especially on rural roads. In this study, in order to determine the most effective factor in the occurrence of accidents, analysis and modeling of effective factors on rural roads of Guilan province in 1392 to 1397 have been conducted. First, frequency analysis was used to evaluate the variables and their frequency. Then, Friedman test was utilized to prioritize the factors and exploratory factor analysis was used to determine the most effective factor in the occurrence of vehicle accidents. Finally, multiple logistic regression models were used to predict the probability of the occurrence of accidents. Based on Friedman test results, weather conditions, road surface conditions and the type of vehicle accident were identified as the first to third factors affecting accidents, respectively. Exploratory factor analysis showed that five factors as the main factors are involved in accidents that the variables of weather conditions and road surface conditions as an environmental factor were recognized as the first effective factor in accidents. Also, multiple logistic regression models with more accuracy in predicting the severity of accidents (84.7%) showed that cloudy weather, dry road surface and wet road surface had the highest effect on occurrence of accidents, respectively. Results of accident sensitivity analysis also showed that logistic regression (with the area under the curve 0.932) was much more accurate than factor analysis (with the area under the curve 0.849), which shows the high power of this model in predicting and evaluating of accidents severity.

It is of great importance to select the estimation and payment methods in construction projects. The cost estimation is one of the most important stages in project management especially during budget determination. Considering the newly emerged Unit Rate Price Schedule by Budget and Planning Organization and lack of comprehensive studies and researches about this subject we tried to show weaknesses and strengthens of this newly introduced method compared to other ones.The research method was a qualitative one using structured interviews by means of MAXQDA10 software for results collection and analysis. The results of research are road oriented as the case study was a road construction one.From the results it is concluded that the most important advantages of this research are relative reduction of payment risk for the contractor, possibility of payment to the contractor for delayed statements compensation and lack of payment to the contractor for the transportation of in-site materials. Simultaneously, the most disadvantages are project start before satisfying tender requirements such as budget allocation, delay of land acquisition and drawings, uselessness in tunnels and underground works as well as the limit of delayed statements compensation to the contractor.

Speed violation is one of the main causes of accidents. High speed not only increases the probability of occurrence of accidents but also increases the severity of accidents. So a vital point is trying to prevent the occurrence of speed violations. In this study, the hourly average traffic speed for Khorramabad to Arak highway is predicted for the future. If the predicted speed is near or exceeds the permitted speed, it is necessary to consider arrangements and preparations to reduce the average speed of traffic by users or the transportation network operators. In order to predict hourly average traffic speed, related traffic data was recorded in recent years. Many new features that affect traffic speed are extracted and used in predictive models. Three machine learning methods, including support vector machine, artificial neural network, and recurrent neural network, have been used. All three methods have the ability to analyze big traffic data, and in addition, the recurrent neural network has more consistency with the time-series nature of data. The results show that for both directions of this highway, by using only calendar and weather features, the mean absolute percentage error of the models is varied between 2.8 to 5.1 percent. Models can predict speeds over 80 kilometers per hour with precision over 80 percent. By adding the observed speed of the previous 3 to 8 hours as predictive features, the mean absolute percentage error of the models is decreased to 2.5 to 4.6.