فصلنامه مهندسی حمل و نقل
سال پانزدهم شماره 2 (پیاپی 59، زمستان 1402)

The air transport fleet is considered one of the most important and strategic elements of the country's transport, which unfortunately has not been seriously considered by the government in recent years. Also, during the last decade, due to the cruel sanctions of the European and American countries, the supply and support of the country's air fleet has suffered a shortage and a crisis. This issue alone can testify to the importance of self-sufficiency in this strategic area, which should be included in the agenda of industrial development and air support of the country. In this research, the researcher tries to propose strategies by examining and analyzing the internal and external environment and factors affecting the development of this industry so that a road map can be provided for the development and improvement of these industries. This important thing should be realized through modeling and structuring of these strategies, which in this research has been planned by using the Dematel method and evaluated by a comprehensive review of the strategies from the perspective of effectiveness and influence on each other. It should be noted that the research method in this study is of qualitative type and it is done in the field of collecting and summarizing information. In the results section, the researcher has achieved to provide a strategic and comprehensive model in the field of supply and support of the country's air fleet, which can be a beacon for the strategic movement of these industries.

The bus transportation system is one of the most important urban public transportation systems and plays a major role in intracity travel and daily travel in all cities. Due to the increase in personal car travel, it’s important to determine the policy for the use of buses on intra-city trips but to achieve this goal, one must know which one of the proposed plans can increase the use of buses. The innovation of the current research is the use of the systems dynamics approach in bus transportation systems in order to achieve this goal. Factors affecting the use of buses have been identified using the content analysis method, and variables such as culture-building, intelligence, and physical-technical quality of the bus have been included in the model, which has not been considered in other studies. The model was implemented in city of Mashhad. After validating the model, two scenarios and seven types of budget policies were implemented on the model according to the experts' opinion. The results of the bus fare scenario showed that if the bus fare rate is not changed, the attractiveness of the bus will increase slightly. The scenario of increasing the budget for improving the bus organization also showed that there is not much change in the use of buses. The results of the policy review also show that the best policy is to reduce the budget for purchasing the bus fleet and increase the funding for culture and intelligence, which will increase the use of buses in the long run.

Increasing population and urbanization have been caused many problems such as: increased traffic in cities, travel time, cost, fuel consumption, air pollution and so on. In the mentioned situation, some methods are needed to increase the safety and efficiency of the transportation system. In this regard, one of the programs that can be implemented to improve transportation is the use of Autonomous Vehicles. These vehicles have attracted the attention of researchers and industries, so that many transportation experts are currently working on this field. This system can act as the basis for economic growth and countries development. In the present study, the roles of AVs in transportation system have been discussed. The main structure of this project is neural network as one of the machine learning methods. The task of this section is to learn the system and make decisions based on the current condition.  Accordingly, the combinations of Dense and Convolutional neural networks and Udacity simulator have been used. It showed that the simulator can help to speed up the process and implementation of AVs. The results indicated that there is high similarity between human driving cars and AVs which are implemented by the Udacity simulator.

This paper proposes an integer linear mathematical formulation for Vehicle Routing Problem (VRP), where the capital cost for deploying each vehicle is minimized together with other on-link transportation costs. The model has been formulated as a multi-commodity network flow model with capacity constraints. It is well known that the computational complexity to this type of problems is NP-hard. Thus, the ACO algorithm, which has been known to be a powerful meta-heuristic algorithm for solving VRPs in large networks, has been adapted to solve the problem. Although the ACO algorithm has repeatedly been used to solve the capacitated VRP, it has a drawback that cannot consider the capital cost of each vehicle along with other operational costs of the vehicles (associated with the total distance traveled within a day) in its initial form. More specifically, naturally it assumes that each vehicle returns to the depot if it becomes full or the demand finishes, each met first; this paper seeks to propose an adapted ACO algorithm in which this assumption is released. To assess the capability of the proposed model in large-scale networks, the case study of Mashhad city, consisting of 253 traffic analysis zones and over than 3800 links, has been considered. Results show that the proposed algorithm converges to near-to-optimal solutions within two seconds of cpu time, which is encouraging.

Shared bicycle systems are proposed to respond to urban mobility challenges as a healthy, efficient and relatively cheap means of transportation. Although these systems are widely implemented around the world, there are still challenges for implementation. The implementation of shared bicycle projects represents an important innovation in urban public transportation. These plans have spread rapidly and now exist all over the world in cities with different economic, environmental and structural conditions. Developing strategies through which to attract new members to join the plan and retain existing members is a fundamental requirement for the success of the plan. The purpose of this research is to identify the effective criteria on citizens' acceptance and use of shared bicycles with the method of synthesis research. The unit of analysis in this research is all English-language articles published in reputable foreign journals with quantitative analyzes on the identification of these factors. By searching in various scientific databases and carefully examining the articles, finally 30 articles related to the topic were found. The seven-step model of Sandelowski and Baros was used to analyze the obtained articles. The results show that the most important criteria affecting the acceptance of shared bicycles by citizens are perceived ease of use, perceived usefulness, attitude, facilitating conditions, cost, service quality, infrastructure, user satisfaction, environmental concern, social effects. , mental norms and the theory of planned behavior.

One of the most important issues in traffic safety is assessing the stability of the fatalities trend. In order to evaluate the effectiveness of the road safety plan to achieve a specific goal or policy objective, it is necessary to measure the stability of the number of fatalities and injuries. The purpose of this study is to study the changes in trend of the fatalities in the provinces of the country, to investigate the ability to model the optimal trend in road safety and also to identify provinces with poor performance with the aim of investigating the causes of a steady upward trend in casualties. In this study, in order to evaluate the safety stability of rural roads in the provinces of Iran, the development of simple trend lines and exponential trend lines has been considered. These trends were developed for the number of casualties on the rural roads of the province, as well as due to the shocks and fundamental changes in the volume of road traffic in recent years for the number of fatalities to the exposure (multiply the length of the road and the volume of traffic) in the province. Based on the results and findings, the provinces of Khorasan Razavi, Kurdistan, Gilan, and Hamedan are the provinces that have had a good performance in terms of reducing the number of casualties caused by accidents on rural roads. Therefore, the best experiences, plans and, documents of the mentioned provinces can be used in order to strengthen and improve the level of road safety in other provinces. Sistan and Baluchestan province also has a steady increasing trend in fatalities due to rural accidents and therefore needs special attention and detailed planning to investigate the causes of this trend.

In today's world, the air transport industry is considered one of the most important axes of development of countries. In Iran, the growth of economic and social activities and the ever-increasing demand have made the development of this sector an inevitable necessity. However, this industry in our country has always been in a challenge during recent decades due to facing many turbulences, which sometimes has led to air accidents. Considering that the media has a significant role in the crisis management process, the air transportation industry has been unsuccessful in using the media capacities to manage the crisis of accidents. The aim of this research is to design a media model for air accident crisis management. In order to identify the factors and investigate the conditions, with proper planning and creating unity in the ‘’informing command’’, media capacities are used in the event of an air accident. For this purpose, in the interpretation paradigm based on qualitative methodology, Strauss and Corbin's data base theory method has been used. 22 in-depth and semi-structured interviews were conducted using theoretical sampling and snowball technique with managers, professionals and experts in the fields of aviation, media and communication industry. By coding and analyzing the content of semi-structured interviews with experts, 515 open codes were extracted. After collecting the codes, 94 subcategories and 46 categories were identified in the form of the main theme. Based on the analysis of the findings, the main theme of causal conditions includes 11 categories, contextual conditions of 9 categories, intervention conditions of 5 categories, strategies of 15 categories, and positive and negative consequences of 6 categories. The findings of this research show that due to the lack of benefiting from systematic communication at the time of air accident, the media's waiting time in order to receive an answer has been prolonged, and by leaving the first narrative of the news to the unofficial media, rumors start to spread and trust level declines, posing a challenge to the process of crisis management in this sector.

Factors such as socio-economic factors, population density, land use, availability of vehicles affect the emergence of urban trips. In this article, an attempt was made to plan the transportation network of 22 districts of Tehran metropolis by using the transportation database. For this purpose, using real data and the LUTI model, the relationship between the effective factors in the mentioned model was investigated using SPSS software and correlation coefficients were obtained in statistical tests, and the correlation level of household variables, accessibility and transportation was also calculated. Then, factor analysis of variables was used to investigate their relationship. Based on the analysis of the real data of 2013 and 2015 collected using descriptive statistics of the variables including mean, standard deviation, skewness and kurtosis, the normality of the variables was obtained and its distribution is symmetrical. It is for these users, in fact, they have a lot of dependence on each other to create a trip. According to the transport density index and based on the travel distance, which are important parameters, different land uses have been investigated and the results have been obtained for the regions. In the travel production part, there is a relatively strong correlation of office, residential and educational uses compared to other uses, which shows the value of the coefficient of determination equal to 0.447, which indicates that 44% of the total traffic changes depend on the 5 relevant factors. Also, in attracting travel, 49% of all traffic changes are related to administrative, residential, and educational uses, and in transportation and with administrative, residential, and educational uses, 53% of all traffic changes are related to administrative, residential, and educational uses. In other words, with the transportation and employees of the administrative department and the education department of Tehran, 53% of the trips and as a result the traffic in the 22 districts of Tehran can be reduced.

Mode choice models and the factors affecting it is one of the most important things that can help planners in this area to make appropriate decisions to improve the quality of traffic for citizens and especially the academic community. The main purpose of this research is to model the mode choice of members of Razi University Kermanshah in their daily trips to the university. For this purpose, the effect of various demographic, socio-economic variables and characteristics of the means of travel on the mode choice of university members was evaluated. In this regard, a questionnaire was used to collect the required data. Instrument choice modeling was done using binary Logit and multinomial Logit discrete choice models. According to the analyzes carried out for the multinomial mode, the most effective factors on the choice means include the available vehicle, the distance from the residence to the university, being a native and having a driver's license, and for the binary Logit variable, which is defined as the use or non-use of public transportation. The most influential factors on the mode choice model were access to a private car with a coefficient of 1.28, use of the bus in ideal conditions with a coefficient of -3.51, and the distance from the residence to the university with a coefficient of 2.59 in the utility function.

In this study the effect of aggregate source on the ageing of asphalt binder ageing in asphalt mixtures has been investigated. Limestone and siliceous aggregates have been used for making specimens with the same binder and aggregate gradation. The mixtures were tested after subjecting to short and long term ageing, and the properties of the mixtures after each ageing condition have been evaluated and compared.  Marshall Stability, flow and Marshall Quotient (MQ), indirect tensile strength (ITS) and moisture susceptibility have been investigated. Results reveal that the mixture made by limestone aggregates has higher Marshall Stability, Marshall Quotient, and indirect tensile strength than the mixture made by siliceous aggregates, while the mixture made by siliceous aggregates has higher moisture susceptibility. The difference between the moisture susceptibility of the mixtures is more after ageing. Results also show that ageing results in increase of Marshall Stability, Marshall Quotient, the ITS in dry condition, and decrease of Marshall flow and tensile strength ratio.  It was found that long term ageing condition of 7 days at 85°C, results in 13 and 62% improvement in Marshall stability and ITS, respectively, in the mixture made by limestone aggregates, while these values for the siliceous aggregates are 17 and 32%. The effect of ageing on the Marshall Properties and moisture susceptibility for the mixture made by siliceous aggregates is higher than that for the mixtures made by limestone aggregates. However, the effect of ageing on the ITS in dry condition is higher for the mixture made by limestone aggregates.