پژوهشنامه حمل و نقل
سال هجدهم شماره 1 (پیاپی 66، بهار 1400)

The optimal locating of facilities has large effects on economic benefits, providing satisfactory service and levels of customer satisfaction.The decision of facilities location mostly is a long-term and strategic decision of the large private and public companies and reliability is important to make this strategic decision so that the system continues to operate with the least damage in case of stop working or failure of one of the components. This paper at the first time proposes a nonlinear integer model for reliable single allocation hub location problem that considers backup hub, alternative routes, and also uses fortification approach to improve the network reliability, while there is the possibility of direct connection between non-hub nodes . Due to the NP hard nature of the model, genetic algorithm is use in order to solve the defined problem and the numerical results illustrate the genetic algorithm has better performance than the GAMS in terms of speed , it also shows great quality answers. The results of the sensitivity analysis show that considering the protection approach has reduced the total cost.

In this study, the effect of the use of two WMA additive sasobit and rheofalt additives on the fatigue properties of the asphalt mixes was evaluated. For this purpose, laboratory samples containing 100 % RAP and a hot mixture were constructed using RAP material, which is separated from the bitumen. The recycled mixtures include a hot recycling sample and three warm (1 non - additive sample, 1 sample containing sasobit additive, 1 containing rheofalt additive). In this research, different experiments such as indirect tensile strength, resilient modulus and fatigue are investigated. Fatigue test was performed on four - point bending test with constant strain level at three levels 600, 800 and 1000 micro - strain with sinusoidal loading. The fatigue life of specimens was evaluated based on a 50 % reduction in the initial hardness modulus. The results showed that sasobit and rheofalt additives had a positive effect on the compression and functional properties of the blends. In the performance of fatigue and low - temperature cracks, the hot mixture was better in spite of the positive effects of additives.

Numerous people have died and economically damaged due to the road accidents. One of the efficient ways of reducing crashes is to predict them before happening. This paper investigated the power of artificial-neural network (ANN) model to predict crash frequencies of Naein-Ardakan road, located in Yazd, Iran. To date, there seems no research done to compare the effects of ANN training functions on prediction performance. This research aimed to determine the proper ANN training algorithm for crash frequency prediction. In this regard, four different training algorithms were investigated. The results demonstrated the outperformance of ‘trainlm’ algorithm. Additionally, it was found that the average daily traffic per lane and gap lengths is the most influential factors in crash occurrences, respectively. The present study can be applied to more precisely explain the effects of independent variables on crash outcomes. An in-depth explanation of the effectiveness of independent variables can assist road safety experts in making better decisions for reducing accidents.

A large number of vehicle rollovers occur in horizontal curves. Designing the shoulders appropriately may reduce the number of these kinds of accidents. Therefore, this study aims at exploring the influence of shoulder characteristics on the rate of rollover accidents. Also, lateral acceleration and drivers’ behavior is analyzed considering the effects of shoulder characteristics at curves. The characteristics considered in this research are width, transverse slope, and pavement. To conduct this research, dynamic simulation is used. The number of scenarios that are indeed the number of observations is 324. Two linear regression models are developed with their dependent variables being the rollover rate and the lateral acceleration. The independent variables are shoulder characteristics, vehicle dynamics (vehicle speed) and driver behavior (encroachment angle into centerline in Degree) and different types of vehicles (Sedan, SUV, and Truck). The results indicate that the shoulder characteristics significantly affect the safety in terms of the roll rate and the lateral acceleration of the vehicles. This effect differs among the different types of vehicles and is measured by the dynamic and structural characteristics of the vehicles. The results of this research are useful for designing safer roads as well as the road safety audit.

The use of steel fibre instead of Rebar reinforcement or in combination with them have advantage such as increasing flexibility, energy absorption and control of crack . Laboratory studies have been performed on the performance of slabs with steel fibres, but no specific numerical study has been performed that enters the fibre properties directly into the analysis process. Steel fibre concrete in this study modeled with finite element method and laboratory work with existing fibre-reinforced slab ‌ compare and validate. Then, with the development of fibre-reinforced slab track model, relies on the rebound under the bed moving a simulated load. The results show that the presence of fibres in the service load range has little effect on the shear and flexural forces of the slab.In the following, using FIB regulations, the process of designing steel fibre concretes and the possibility of using steel fibres in slab track is examined. The results show that the use of fibres in the slab alone does not have the necessary flexural strength to withstand the incoming loads and the crack width is obtained several times the allowable value of the regulations. As a result, the combination of fibres and reinforcement is used to control cracks and the design graph of the combination of fibres and reinforcement in the slab is obtained. The results show that with the addition of fibres, the amount of reinforcement required is slightly reduced and the crack width is significantly reduced. For example, in the case of axial load of 25 tons, load speed of 120 km / h and hardness of 32,000 kN/m with fibre volume percentages of 0.25, 0.5 and 0.75 in slab track model, the reinforcement used is reduced by 26 , 30 and 35% respectively.as well as crack width used is reduced by 3.5 , 4.9 and 6.3% respectively.

Nowadays, construction on problematic soils is inevitable owing to the growing scarcity of land worldwide. Problematic soils are commonly characterized by low strength and high compressibility. Thus, the mechanical properties of these soils should be improved. In recent years the researchers have attempted to present approaches based on environmental measurements. One of the methods recently considered in the improvement of sandy soils, is Microbial-Induced Calcite Precipitation (MICP). In order to accelerate the MICP process, it is possible to improve the soil structure cementation and soil engineering properties by creating Urea microorganism. In order to do this, a solution containing bacterial cell and cementation is required which includes urea and one of the Calcium ion sources such as CaSO4.2H2O, CaCl2. 2H2O, CaCl2. In this paper, in order to accelerate the calcite precipitation, a Bacillus bacterium called Bacillus Pasteurii is used as catalyzer of this chemical reaction. In order to investigate the effectiveness of time factor on improving cohesion of silty sand from Firouzkooh city, Iran, an experimental study consisting of 5 direct shear tests were performed. The time taken for the experiments was 3, 7, 14, 21 and 28 days from MICP. The results of this research demonstrated that, over time, cohesion of improved silty sandy soils increased by bio-microbial method. This indicates the role of the growth of bacterial cells and accelerates the progress of the MICP process and the precipitation of calcite crystals in the pores. The results from scanning electron microscope (SEM) confirmed this finding. SEM images indicated that the rate of calcite precipitation increases with time. However, the rate of growth of bacteria depends on their amount of optimal growth or volume of residual pores of the soil that can be decreasing or increasing.

These days, many researchers and planners pay a lot of attention to the mutual relations as a common border between transportation planning models and land use models. The impacts of land use patterns in trip generation and trip distribution are of high significance. Using integrated land use and transportation models causes the possibility for forecasting different areas’ development, changes in trips patterns in traffic zones and also provides more precise predictions and reduces errors. These scenarios may contain different control policies, strategic projects and developing infrastructures. Therefore, in this research, a pattern of location choice for living and working with following goals has been provided by using discrete choice model in Urbansim software for Qom city: providing an integrated transportation and land use model regarding land price and people behaviors, analysis of different effective factors in location choice for living and working to predict the changes in locations, calculating the effects of local house pricing policies on transportation. For conducting this research, effective variables have been identified and different social and economic information were gathered from authorities and governmental organizations. At the next step, according to the base year information, the processes of making models and calibration have been done and all land use models and sub models were made. It is followed by evaluating based on unused data and finally presenting a set of integrated models in order to recognizing population and job distribution in the horizon year. Results show that accessibility between traffic zones, economic and social variables such as income, number of people in each family, car ownership and land price are important factors in determining living and working locations in Qom. Furthermore, people in different age groups with different income have various priorities for their living and working locations.

Given the importance of distribution planning among the chain loops of a firm, in this research, the routing problem of cargo transport fleet is considered as the issue of transportation routing ( VRP ). Among the innovations of this model one can point, it is possible to define the penalty for violating the time window (delay and rush to delivery of the product) to ensure customer satisfaction, considering the direct relationship between weight and fuel consumption, which reducing weight, in addition to reducing costs, reduces the destructive effects of Greenhouse gas, air pollution and carbon dioxide. Reducing drivers costs, which eventually leads to lower total costs, in addition to make lean leads to Increase customer satisfaction, makes use of the concept of service time in a variety of multi product and variable conditions, taking into account the cost of product distribution .In this research, considering the Shahd-e-Pak as a case study, the distribution of product from warehouse to the consumer is modeled as a supply chain. Considering the NP-HARD problem in order to find the near optimal solutions, after setting the parameter in a comprehensive search method, the model is modeled in single-objective and multi-objective mode using Python software using heterogeneous genetic multi-objective algorithms, 2 (NSGAII) and Particle Swarm Optimization (MOPSO). At the end, these algorithms were compared with performance evaluation criteria such as runtime and the quality of the answers, and the highest algorithm was determined for each criterion. The results indicate the effectiveness of the proposed model and the superiority of using a steady-to-definitive analysis method that leads to optimization Transportation path, cost reduction and ultimately customer satisfaction. Also, by comparing the performance evaluation criteria and the duration of the implementation of the model, it was found that the MOPSO algorithm is more efficient than NSGAII.

The addition of macro-fibers to concrete slabs on ground have been shown to increase flexural capacity, fatigue resistance, reduce crack deterioration rates, and assist in shear transfer across joints and cracks. A laboratory study was performed to determine the benefits of macro-fibers in roller-compacted concrete (RCC) for pavements by measuring the change in RCCs mechanical properties and comparing it to conventional fiber-reinforced concrete for pavements. Six fiber types, four synthetic and two steel, with several fiber geometries were incorporated into RCC mixtures at two dosage levels (0.2% and 0.4% by volume). The addition of synthetic macro-fibers increased the maximum dry density (MDD) over the control RCC mix by reducing the internal friction between aggregates whereas steel fiber had a limited impact on the MDD of RCC. For several fiber types, the resultant RCC with fibers had a statistically significant increase in compressive and split tensile strength relative to the control RCC mix. The addition of fibers did not increase the flexural strength of RCC but did noticeably improve the post-peak and residual strength capacity of RCC. The increases in residual strength were dependent on the fiber type and geometry, similar to the behavior in conventional Portland cement concrete (PCC). The fracture properties of RCC with fibers based on disk-shaped compact tension (DCT) tests were shown to be similar or greater than PCC with fibers which indicates both RCC and PCC pavements, when properly constructed will have similar fracture and fatigue resistance.

In competitive consumer markets, building and maintaining a good relationship with customers is essential to long-term business survival. Currently, firms are applying Customer Relationship Management (CRM) to facilitate the maintenance of this relationship. Also, the number of customer relationship management implementations has grown dramatically in recent years. However, few academic studies of the issues associated with the implementation of the concept are available. The purpose of this study is to identifying and prioritizing of the factors affecting on the implementation of the optimal customer relationship management in transportation and terminals organization of West Azerbaijan province. This study is a descriptive survey and exploratory factor analysis has been used for the purpose of extracting infrastructure structures. The statistical population of the study consisted of managers, experts, and employees of the transportation and terminals organization of West Azerbaijan province. The research questions were analyzed using One-Sample T-Test and confirmatory factor analysis. In this research, the effective factors (e-learning, readiness to change, knowledge management, providing services electronically, knowledge management, structural features) were identified in the process of implementation of the customer relationship management system at the transportation and terminals organization of West Azerbaijan province and the results showed that in the process of implementation of customer relationship management is the highest rating assigned to structural features and the lowest rating is assigned to the knowledge management.

Overlaying the old pavement with new surfacing material is one of the commonly used methods for rehabilitating deteriorated pavements. The existing cracks in the old pavement propagate through the newly laid overlay and reach the free surface in due course of time. This phenomenon is referred to as reflection cracking. In general, using of stress absorbing membrane interlayer (SAMI) is one of the methods to control reflective ceacking. The main aim of this study is the evaluation of performance of SAMI in high stress level. The SAMIs in this study made by porous asphalt and Stone Mastic Asphalt (SMA) and paved between the old asphalt pavement and new surfacing layer. To do so, first test specimens made up of 2 and 3 layers which respectively were without and with SAMI. Afterwards to investigate the performance of SAMIs, dynamic creep test and specific fracture test by new geometry carried out. The fracture test able to simulate/model reflective growth in mixed modes I/III of fracture mechanism. The findings of study indicated that using this type of SAMIs reduce the fatigue life and cannot able to retard reflective cracking. Also, using SAMIs result in deformation increase.

Inflation is a detrimental economic phenomenon and imposes high economic and social costs on societies at high rates, but the main economic damage of inflation is the uncertainty about its future value. Therefore, this study analyzes the relationship and the uncertainty effect of inflation on capital in the road transport sector during the period 1991-1995. In the present study, the economic effects of inflation uncertainty on Investment in the country's road transport sector are investigated. The EGARCH model is used to calculate inflation rate uncertainty. To estimate the main model, self-regression model with distributed interpolation is used and EVIEWS10 software is used to estimate the model and interpret the results. The results show that there is a conditional heteroscedasticity in the inflation rate, which means that there is uncertainty in the inflation rate. Also, the results of the model estimation show that both in the short run and in the long run as the GDP increases, investment in road transport increases and with rising inflation uncertainty, investment in road transport will decrease. Interest rates, both in the short and long run, have a negative impact on investment in the road transport sector. Also with respect to the error correction factor in the ECM model it can be stated that the adjustment rate is appropriate to the equilibrium and long-run value, So that in each period, about 0.36 error of equilibrium is adjusted and in the short run tends to equilibrium and exponentially in the long run.

The use of futuristic approaches in order to study the effects of the construction of breakwaters on neighboring community makes it necessary to pay attention to the issue of scenario planning. Scenario writing is a very effective and useful way to plan for the medium and long term in uncertainty situations. The aim of this study is to investigate possible scenarios in order to improve the impact of breakwaters on the socio-economic aspects of the life of neighboring community. This is an applied purpose study which is considered an analytical method based on its nature. The required data were obtained through investigation of scientific literature and Field Observations. A questionnaire was distributed among executive officials to compile the scenarios. Collected data was analyzed using MIC-MAC software. According to the Structural analysis of MIC-MAC software, geographical location and its properties has the most impact on dynamics of the breakwaters. Based on uncertainty, the factors "use of breakwaters", "management of breakwaters", "interaction between relevant institutions and beneficiaries" and "fair distribution of facilities", play an important role in the way that breakwaters affect the neighboring community. The combination of these axes formed four scenarios called gold, silver, bronze and gray. In the first scenario, called the Golden Consequences, the efficient functioning of the relevant institutions and the balance between socio-economic components will lead to the Develop a brilliant future in neighboring breakwaters communities. The best impact of the construction of breakwaters is described in the Gold scenario.

Currently, road transportation is the main mode of freight transit in Iran and about 90% of freight transit is done through this mode of transportation which is not in line with the transportation policies that based on them 70% of the freight transit should be done through road transportation and 30% of the freight transit should be done through rail transportation. However, Iran's railway network is very wide and we can increase the share of railway in freight transit. Therefore it is important to recognize the effective factors which increase the share of rail transit. The purpose of this research is to recognize the factors increasing the utility of railway transit corridors and to improve the competitive position of railway in freight transit. So the concepts of utility and transit are described in the first place, then the factors affecting the utility of railway transit corridors from the perspective of the owner of goods are determined by making a literature review and investigating the opinions of experts. These factors include transportation cost, commercial speed, reliability, safety, the system of tracing wagons and service frequency. Then a utility function for Bandar Abbas- Sarakhs corridor is developed based on the mentioned factors. At last, a dynamic model to evaluate the utility of the mentioned corridor is developed and after verifying the validation of it, the model is simulated by vensim PLE software for 20 years. The results of the simulation show that simultaneous improvement in reliability, the system of tracing wagons and commercial speed and also giving discount on the cost of transportation according to the demand of the owner of goods can play a significant role in increasing the utility of the mentioned corridor, and changing only one factor will not result in major changes in the utility of the corridor.

In this paper, we introduce the sustainable routing problem in a network with forward and reverse flows, in which different economic, environmental and social factors are considered in a bi-objective mixed integer linear programming mathematical model. The purpose of the problem is to design the service routes and determine the optimal speed of vehicles in such a way that, on the one hand, the amount of fuel consumed and, consequently, pollution caused by the transportation process are minimized, and on the other hand, in order to create satisfaction among drivers, the workload of different vehicles in terms of the duration of tour is balanced. A comprehensive function is used to estimate the amount of fuel consumed, in which the amount of fuel consumed is a function of the distance traveled as well as the speed, load, and technical characteristics of the vehicle. In order to solve the problem optimally, the augmented epsilon constraint method is used. Also, for solving large-scale instances, two multi-objective meta-heuristic algorithms based on genetic algorithm and fireworks algorithm have been developed. In order to increase the efficiency of these algorithms, a local search method is also used in their structure. The results of solving various examples represent a better performance of the fireworks algorithm. Also analysis of the pareto-front shows that with a one percent increase in fuel cost, the longest tour can be reduced by more than 20% and the difference between the running times of different machines is reduced by 15%. This difference can also be reduced by up to 25% by increasing fuel consumption by 3%.

Dense clay layers are one of the most common impermeable layers in most geotechnical structures such as earth dams and urban and radioactive waste landfills. Due to the specific geotechnical properties, these layers are damaged by cracking over their lifetime. These cracks increase the permeability of the layer and reduce its efficiency. Considering the necessity of knowledge and understanding of factors affecting the stability of geotechnical structures made with these layers, in this research, it has been tried to use a self-resilient property of clay soils to improve soil yield in different conditions. In the present study, it has been shown by numerous experiments that increasing the plasticity index's clay soils can increase the crack restoration rate. The results show that the addition of nanomorillonite to soil improves the self-healing process of the cracks; the time elapses the effect of this increase in the process of repairing cracks created in the specimens. The discharge rate of the samples is measured relative to the time elapsed during the self-repair and are examined according to the graphs. The experiments showed that the percentage of nano-clay montmorillonite is unaffected and reduces the amount of flow in the specimens, which is the self-restorative symptom of cracking by the addition of nano-clay. The total amount of discharge outflow in nano-clay samples from the non-additive samples was much lower, and nano-clay can be used as repairing cracks in clay soils at a depth of 5 cm.

Low cost carriers provide many predicted economic advantages such as increasing the domestic and international tourism, job creation, and generation of tax by the increased business activities. The presence of low cost carriers in the market can facilitate the access to the destinations and help the low income class to experience the trips they have not had so far. So, this research investigates the factors affecting the travelers’ intention for purchasing from low cost airlines. As a result of reviewing the literature and the theoretical framework, five variables were found to explain the travelers’ behavioral goals in purchasing from low cost airlines. These variables include: price, service quality, airline reputation, airline safety, route availability and convenience, and frequent flier programs. The population includes all the travelers of the flights provided by this airline. Out of the mentioned population, 384 people were randomly selected as the samples based on Morgan-Krejcie table. The research is a descriptive cross-sectional survey performed in 2020. Data collection was done by a questionnaire. Data analysis was done in terms of descriptive and inferential statistics, and the hypotheses were tested by structural equation modeling in Lisrel software. The results suggested the positive effect of the service quality, airline reputation, price, and safety on the travelers’ intention for purchasing from low cost carriers. Furthermore, the results provide a useful guide for development of low cost airlines.