پژوهشنامه حمل و نقل
سال هفدهم شماره 2 (پیاپی 63، تابستان 1399)

Sustainable transportation as one of the main factors affecting the economic, social and environmental characteristics of society can be used in the process of changing, transforming and evolving any society. Metro (urban trains) is clean, safe, fast and secure in the urban transport network , has a rough role in the economic, social and environmental issues caused by traffic problem. So, given the positive effects (urban trains), the development of a national project is very important. In this research, metro lines of Tehran metropolis in terms of sustainability of transportation by 8 cost indicators and 6 profit indicators were studied in total 14 indicators. The BCR, EUAW, NPW and DEA Method have been used to identify the stability of the metropolitan area To conduct this evaluation, firstly, with the library and field research, the current status of the public transport of the city rail (metro) in Tehran was be analyzed .And the results of this research indicate that Tehran Metro Line 2 is considered as the most stable line in terms of total economic, social and environmental indicators, and line 3 has the least sustainability. Also, by (DEA) method, lines 1,2,4,5 are acceptable in terms of performance evaluation and line 3 is not acceptable.

Various environmental conditions could have a significant effect on traffic flow. Understanding the effects of environmental conditions on a vehicle’s speed could provide an accurate estimation of travel speed and traffic management strategies adoption to prevent traffic crashes. In this paper, the speed of vehicles had been investigated based on different variables, such as the effect of some weather conditions (such as rainy, foggy, cloudy and sunny), air temperature, speed variations during nights and days, heavy vehicles percentages and vehicle volumes. In this research, the effects of these variables on vehicle speeds have been studied in order to decrease suburban crash frequencies, using a multiple linear regression model. Required data have been gathered from Iran Road Maintenance & Transportation Organization and Meteorological Organization Government agency in 2014. According to 7541 hourly samples at Tehran-Qom freeway, the results of the proposed model shows that rainy weather and night and day speed variation caused 1.355 and less than 1 kilometer per hour reduction in speed, respectively. Also, the proposed model has an acceptable and reliable error in speed prediction and the evaluation criteria such as mean absolute error, mean absolute percentage error and root mean square error were 3.579, 4.034 and 4.996, respectively.

Today, coronavirus (COVID-19) has become a major global threat. A lot of programs are proposed to prevent and estimate its associated processes due to the high risk of its transmitting among humans and the lack of drugs and vaccines to stop it. COVID-19 was first reported on 31 December 2019 in Wuhan, China. After a short time, the disease spread to other countries and became a global disease. According to the lives of most people, the transportation system has a significant impact on controlling or spreading the disease. Therefore, this subsystem is considered as an element of a proposed system dynamics model in this article. This model examines two different scenarios for infected people, mortality rates, and recovery rates. The system is designed according to various subsystems such as health care systems, transportation, public contact, and the capacity of food and drug networks. In the proposed model of this paper, a flow structure is utilized to show the effects of different sections of systems and subsystems depend on the COVID-19 outbreak over a long time. The results of the proposed model show that different parts of the main system and its related subsystems have different sensitivities and effects. Analyzing this model will be useful for government decision-making based on the results of the two scenarios examined. It is assumed that there is no effective vaccine or drug in the next 6 months. The results of the proposed model show that different changes in subsystems could increase COVID-19 mortality in six months from 10,500 to more than 1.6 million. Therefore, the mortality rate of this disease depends on the policies and behaviors of the factors influencing the model. Consequently, the mortality rate can be reduced based on proper planning against each scenario.

One of the most important parts when any accident occurs is the issue of control and management before and after the disaster, and if this issue is not taken into account, another secondary catastrophe will occur within the main catastrophe. Therefore, in this study, a random integrated model is proposed. In which two categories of decisions are considered; decisions of the first stage of determining and controlling the inventory of distribution centers and location of distribution centers for pre-disaster and decisions of the second stage for post-disaster, including reviewing the flow of injured, Corpses, homeless and relief items in the network and the allocation of vehicles for this flow. Objectives of this paper include (1) maximizing the probability of successful passage of routes by increasing the reliability of routes, (2) minimizing relief costs pre-disaster and post-disaster, by considering the time window, (3) Minimize maximum uncovered demand for relief goods, for all centers in possible scenarios and situations. Considering the scenario uncertainty situation along with the uncertainty of the route and demand, multi-commodity, several modes of transportation and covering tour are among the innovations of this research. To validate the proposed model in small and medium dimensions, Epsilon restriction method in Gams software environment and for case study (Region 1 of Tehran) in large dimensions has been solved using Invasive Weed Optimization algorithm. The results of the analysis indicate that the Invasive Weed Optimization algorithm will be able to solve the model with the least error compared to the exact solution and less time. Also, as the capacity of distribution centers increases, the cost decreases and as demand increases, the number of established distribution centers increases, and as the coverage radius increases, the length of the tour decreases but the number of unoccupied accident hotspots increases and relief costs, including transportation costs, increase.

Safety indicator and range of controlling accidents is considered as one of the important criteria of evaluating transport networks. One of the effective instruments in controlling accidents and traffic is the ability to predict accidents that given this issue, traffic can be managed and the instruments of controlling speed and traffic are used. So the prediction model of the impact of using types of speed bumps in decreasing accidents has been investigated and presented in the research. For this purpose, data related to accidents in 50 junctions and U-Turns during 5 recent years in Ghaemshahr have been studied. Through field studies, parameters such as speed of vehicles, width of speed bump, height of speed bump, distance from junction, the numbers of crossing line and distances of warning signs have been selected as variable and affective parameters on the numbers of accidents. By using scattering models, the way of changes of different parameters were evaluated based on the numbers of accidents in the different places and the final model was obtained by using regression analysis in order to be used in the prediction of accidents. The results showed that if the warning signs are not used in the junctions with speed bump, it will increase the numbers of accidents up to 18% that the increase in the junctions with speed hump is about 11%.Using speed bumps and speed humps with non-standard geometry will increase the numbers of accidents 5 to 12% that the increase in the junctions having speed bumps is more than the increase in the junctions having speed humps.

In Recent years, different Traffic schemes such as the Odd-Even day plan starting from the door of each house or the extension of traffic congestion zone to the Odd-Even plan range have been implemented when vehicle emission rates reached their maximum amount in Tehran. In this study, according to the approved plan of the Emergency Committee for air pollution in Tehran to extend traffic congestion zone to the Odd-Even plan range in Tehran in the third and fourth week of November 2016 and by using the information obtained from the amount of personal car usage of citizens in a selected area of Tehran, which includes 15 intersections and their traffic statistics harvested by the SCATS system, the volume of cars and their emissions rate in this zone during the above-mentioned period and also in the second week of November and the first week of December 2016, during which the Odd-Even plan was also in effect, was simulated and calculated with Aimsun Simulation software. In another stage of this research by using distributed The results shows that during the weeks that Tehran traffic congestion zone extended to the Odd-Even plan range, and Specifically the comparison for the first day of implementation of traffic congestion zone in the range of Odd-Even plan with the same day in the previous week (implementation of Odd-Even plan range) in this research, produced cars emissions for the CO, HC and NOx pollutants has been decreased 20, 18 and 14 percent.

This paper presents post-cyclic-monotonic behavior of BOF and EAF steel slags as ballast and subballast layers with and without geogrid or tire chips, and comparing their behavior with limestone material. Tests were carried out by the large scale triaxial equipment. The confining pressures are chosen with respect to the stress levels in typical rail road track. The tested specimens were prepared by maximum dry density. The used square shape geogrid has aperture sizes of 25*30.5 mm and the depth of placement about 5cm above and middle of subballast. Size of tire chips was 12.7-25 mm and mixed 7% by weight, only in ballast layer. Maximum deviatoric stress, secant modulus, unloading-reloading modulus, friction angle and particle breakage are investigated. Results indicated that performing cyclic loading on ballast layer before the post cyclic-monotonic tests decreases the axial strain corresponding to maximum deviatoric stress. Post-cyclic-monotonic friction angle of ballast and subballast with and without geogrid ranges from 57-65°. The friction angles of the steel slag of ballast, subballast and ballast/subballast specimens are similar to traditional ballast materials. The values of and decrease as moisture of specimen increases. Average poison ratio for mention layers is about 0.3. Marsal breakage index (Bg) of the single layered steel slag ballast is almost two times of the limestone ballast. Presence of steel slag subballast increases Bg of the steel slag ballast to about 2 times. According to fouling and breakage indexes of steel slag ballast under post cyclic-monotonic loading is relative clean. Saturation of ballast specimen causes increase of particle breakage, therefore the drainage of ballast materials is necessary. Usage of tire chips is not recommended in ballast due to high rate of decreasing of modulus and friction angle. Results indicated that the steel slag particle may be used as natural aggregate in ballast and subballast layers.

The purpose of this study was to investigate the relationship between human resource management flexibility and operational performance in the maritime transport industry, and in particular in Khorramshahr port. Meanwhile, the role of learning and innovation is emphasized. This research is descriptive and causal in terms of applied and research method. A questionnaire was designed based on a model based on theoretical fundamentals of the research. The validity, dimensions and items of the questionnaire were confirmed by the supervised professors and also by reliability, using Cronbach's test. In this study 150 employees of Khorramshahr Seafarers' Organization were surveyed. Data were analyzed using SPSS version 22 and LISREL software version 8.51. The results obtained from structural equation tests showed that all hypotheses were approved. The flexibility of human resources has a positive and significant effect on organizational learning capability, innovation, and ultimately on operational performance in marine transport. Considering the amount of path coefficient of main hypotheses, organizational learning capability with the coefficient of path 0.61 has the most effect on the operational performance of marine transport.

In most mix design methods, hot mixture asphalt (HMA) is considered to be a single object and only its macroscopic parameters are determined. This is because the microstructure of HMA is very complicated. Asphalt mixture is heterogeneous in nature; therefore, macroscopic parameters alone cannot describe the mechanical behavior of the mixture. In this paper, the analysis and evaluation of microstructure parameters of aggregates in field asphaltic samples are compared to laboratory samples in different compaction energies. Image processing and quantification of the internal structure parameters of the mixtures were performed using two-dimensional images from the cut-off of samples and iPAS2 software. The results of the comparison between the parameters of micro and field samples showed that the number of contact points in the cores was close to the number of contact points of Marshall Samples, which were made with moderate compaction energy. It was also determined that by examining mixtures of asphalt mixtures, new and useful information can be obtained that confirms the necessity of using micro parameters in the mixing design of asphalt mixtures.

Today, steel is one of the most used materials in industry and its annual consumption is increasing. One of the most important by-products of steel making is steel slag. The use of steel slag as a waste of this industry, can be applied in geotechnical  applications  such a road embankment in order to reduce of the slag disposal, as well as preventing the destruction of natural resources, is of particular importance. It is necessary to determine the geotechnical engineering properties of steel slag produced from different steelmaking operations and assess the potential usage in road and railways embankment construction.  In this paper, physical, compaction properties, California Bearing Ratio’s (CBR) and characteristics of steel slag as a base and sub base of road material and sub ballast of railway were studied. Two types of steel slag, Blast Oxygen Furnace (BOF) and Electric Arc Furnace (EAF) slags which produced in Esfahan Steel Company and Esfahan's Mobarakeh Steel Company respectively are used in this research. The range of the particle size distribution of the specimens has been selected in accordance with the characteristics of the road pavement as well as the existing laboratory facilities. In this research, California Bearing Ratio (CBR) tests were carried out on two types of slags (BOF, EAF) with two types of particle size distributions and with two different compaction methods (standard and modified) in soaked and un soaked conditions. Based on obtained results mentioned slag have no plasticity index. Moreover, dry unit weight varies between 1.94 to 2.74 gr/cm3 and optimum moisture content varied between 8% and 12.5%. The CBR values varied between 88 to 199 for BOF slags and 185 to 490 for EAF slags in socked and unsocked conditions. According to CBR test results; these materials can be used in road base and sub-base layers by applying less compaction effort than in normal condition.

Permanent deformation or rutting is one of the most important distress modes that affect the life of flexible pavements. This type of distress is often observed on the roads that are situated in tropical regions. The properties of the constituent materials play a significant role in the construction properties of the pavement. The use of porous gradation and high binder grade for proper binding in the structure of mixes is known as the methods for improving the properties of mixtures. One of the mixtures made on this basis is Stone Matrix Asphalt mixtures (SMA). These mixes are a type of hot mixed with the coarse skeleton and the high binder and filler, which plays a key role, with the importance of the type and the tar properties used, as the binder of rock particles and the factor that has to endure the stress of the shear stress between aggregates.  On the other hand, due to the high percent of binder and the prevention of binder, the use of additives such as fibers or polymer materials is inevitable. The use of polymeric additives in addition to improving the binder properties, with the increase binder viscosity, also decreases binder drain down. Also, one of the recently applied additives to enhance the binder properties is Nano - clay. The aim of this study is to evaluate the effects of Nano clay as the main additive to binder to improve the binder properties alongside the SBS and fibers, in order to increase the loading resistance of asphalt and to correct its technical properties against the rutting. So, control asphalt mixtures containing of 60-70 binders with 0/4% fiber blended into mixture or modified bitumen mixed by 5 %, along with a montmorillonite additive of 1 %, 2 %, 3 % and 4 % for both pure and polymer bitumen. In this study, the Marshall test, dynamic creep tests and delamination were performed on different samples. The results of these experiments show improved performance of samples containing Nano - nanoparticles with an addition of Nano clay to 3%, which is best achieved performance in polymer modified mixtures.

Traffic accidents are among the most important determinant factors in the quality of the country's roads and as the quality of country roads ensure safe transportation of passengers and goods. Consequently, economic and social and cultural development will have a great impact on every country. Therefore, one of the important parameters in the utility of any road network is the safety of those accidents and accidents. The accidents are negatively affected by the accident rate and its intensity on the road safety, reducing transport rates from that route and reducing the economic flow. The occurrence of accidents at a macro look also causes mental and mental issues at the community level and in the dimension of the family. In 2000 to 1388, some 235000 people have died due to accidents in Iran. The safe distance is dependent on several factors, such as path conditions, allowable speed, allowable speed, type of driver behavior, age and gender, type of vehicle, as well as the prevailing atmospheric conditions. The absence of safe distance is a major cause in the front of a traffic accident, which is one of the most common accidents in our country, thus investigating the behavior of drivers in respect of safe distance and investigating the effective factors on this issue. In this paper, investigating the status quo, drivers ' behavior, the statistical analysis of the accident - based accident on the Sari- Neka highway has been studied as case study. Then, parameters such as speed, time distance and space between vehicles were determined and the solution was proposed to measure drivers ' behavior in this study.

Now days, reclaimed asphalt pavements are used in the production of asphalt mixtures. The use of this material has too many economic and environmental benefits. Beside, warm mix additives are materials that they reduce production temperature of asphalt mixtures and improve their workability in the constructed pavements. There is always a question that “what are the effects of reclaimed asphalt pavement and warm additive on the mix design parameters of asphalt mixtures?” In this research, the simultaneous effects of reclaimed asphalt pavement and a warm additive named Sasobit on the technical properties of asphalt mixtures were evaluated.  For this purpose, an experimental plan was designed based on the response surface method for reclaimed asphalt pavement (from 0 to 50%), asphalt binder content (from 4 to 6%) and Sasobit content (from 0 to 3%). Then, the volumetric and strength properties of these mixtures were determined and compared with the Iranian pavement code criteria. Obtained laboratory results showed that an optimum point for fabrication of asphalt mixtures containing reclaimed asphalt pavement is a mixture with 4.6% asphalt binder, 12% reclaimed asphalt pavement and 3% Sasobit additive. Also, increasing the amount of the Sasobit showed that it increases the value of the Marshal strength, asphalt unit weight of mixtures and it reduces its air voids.

The main role of feeder in urban networks is to increase the coverage of rapid public transportation systems such as subway and bus rapid transit. The high complexity of the exact methods of designing feeder networks motivates researchers to apply heuristic and meta-heuristic methods to find approximate solution of feeder network design. This paper presents an innovative approach to design of feeder network for a subway line using a two-stage heuristic method. The proposed method has been applied in Sioux Falls as a test network which is often used in transit network design. According to the proposed method, at the first stage, a number of primary routes are generated as initial solutions; then these routes are screened according to a set of parameters such as the ratio of the covered demand to travel time, maximum and minimum limit for feeder network length. At second stage, frequency restrictions, the number of routes and covered percentage have been used to select final routes. The proposed method was used in the test network Sioux Falls that improved the demand coverage for public transport system. The demand coverage with the limit of 3 and 4 lines for feeder network are equal to 65.22 and 78.42 percent, respectively.

One of the most important expectations of asphalt binder additives consumers is a reasonable change in rheological and mechanical behavior of original asphalt binder. Crumb rubber is a well-known modifier commonly used to enhance rutting resistance, fatigue behavior and thermal cracking at low temperatures of neat asphalt binder. Generally, rheological and mechanical changes of neat asphalt binder in presence of different types of additives are investigated within linear viscoelastic range. However, evaluating non-linear behavior of neat and modified asphalt binders at higher temperatures, higher stress levels and higher loading rates is important as well. In this study, implementing dynamic shear rheometer (DSR), the creep – recovery test was performed to evaluate rheological behavior within non-linear viscoelastic range of asphalt binders modified with three different dosages of crumb rubber including 10, 15 and 20%. The experimental results were analyzed based on simple theoretical related to non-linear viscoelastic behavior as well as generalized non-linear fractional viscoelastic model. The analysis showed that adding crumb rubber to neat asphalt binder causes an increasing
non-linear behavior which means improvement of rutting resistance at 40 degree of centigrade. Also, increasing the dosage of crumb rubber amplifies this trend.

Asphalt concrete cracking in cold regions is one of the most critical damages of asphalt surfaces. In addition to the cold in some regions, we also see rain that the combined effect of these two factors causes frozen asphalt. In this case, asphalt damages will drastically increase. In this paper, the fracture resistance in saturated hot mix asphalt samples under the influence of freeze and thaw cycles will be studied. For this purpose, a few asphaltic samples that have similar materials, aggregation and construction conditions were made as SCB, then they were saturated. Then different temperatures (-5 and -15°C) and cycles (1, 3, 5, 7, 9, 11) were applied to them. The effect of these parameters on the critical stress intensity factor was studied in 4 fracture moods: tensile mood,(tensile mode, shear mode and two mix modes). The result of this study shows that by increasing the number of freeze and thaw cycles, the fracture toughness will be reduced significantly. As it is, until the seventh cycle, the decrease of the fracture toughness will be increased significantly, and after the seventh cycle, its severity will be decreased. The other result of this study is that with a temperature drop of -15 ° C, the fracture toughness will be increased.

Comparing and evaluating the road safety performance is desirable in trans-national levels, because each country can achieve a better and deeper understanding of its road safety status. In this study, a subset of multi-criteria decision-making methods, called the outranking methods, including PROMETHEE and ELECTRE methods was used to evaluate the road safety performance. In these methods, the Analytical Hierarchy Process method is used to obtain the weights of the indicators, which are used as input weights in the PROMETHEE and ELECTRE models. The methods were used for Iran and a set of developing countries in order to examine the situation in Iran compared to the others. Then, the results being compared with the number of road fatalities per hundred thousand people for these countries as the reference point. According to the results it was found that, among the five road safety pillars, the pillar of road safety management is the most important and the pillar of post-crash response is the least important one. Also, the lead agency sub-pillar is the highest importance in the road safety management pillar and the child restraint sub-pillar is the least importance in the safer road users pillar from expert's point of view. Among the 15 countries studied in this study, Poland found the highest rank and is known as the best-performing country. In between, Iran ranked 13th, reflecting Iran's relatively poor performance against other countries.

Todays, transportation is one of the main elements of economic prosperity in the world and railway is one of the most important methods of transportation in Iran and in the world, which the main reason of its utilization is the appropriate cost against the capability of a great mass of goods and a large number of passenger’s transportation. Population growth and development of economic relations have led to increase utilization of transportation infrastructures, especially railways. Our country is not an exception and knowing that the railway system is one of the oldest transportation arteries, it is in danger of amortization and destruction. Bridges, as the most important road and railway infrastructure, have the most vulnerable in utilization increase phenomena that some signs of vulnerability are seen in parts of the railway system in recent years, and set the authorities thinking. The important point is that if regular maintenance and retrofitting programs in order to increase the capacity of these bridges are not arranged, it will lead to irreparable consequences. In order to help Iran bridge management system with considering all above issues, the present study prioritizes the need for maintenance and also optimization of corrective actions of the bridges of Zirab – Gorgan part in Garmsar – Gorgan line of north and north-east 2 Islamic Republic of Iran railway by the study on them. To do that, the multi – objective particle swarm optimization Meta-heuristic algorithm is used for the optimization of corrective actions. Also considering the four scenarios to select the number of bridges under repair and 16 conditions of problem to be solved by the defined algorithm, the proper and optimized conditions is introduced in different scenarios and budgets to use in maintenance strategies and the most effectiveness achievement.