جاده
Year:2023 | Volume:21 | Issue:115|Papers Count:21

One of the inevitable necessities for the development of the rail transport network is to pass through desert and sandy areas. At the same time, desert railways increase maintenance and repair costs, reduce speed and block the line during operation, and even cause the train to derail. So far, various solutions have been proposed to deal with quicksand in desert railways. One of the newly developed methods is the hump slab track, which seeks to control and pass the amount of incoming sand from the railway track. In this system, the ballast material is removed and the height of rails is raised by means of concrete supports known as humps. As a result, channels for the passage of sands under the rails are created. The geometry of the hump should be such that, in addition to favorable aerodynamic conditions, it provides maximum free space for sand to pass through. In this research, with the aim of optimizing the geometry of the hump, different sections for the hump have been investigated and then two main sections including oval and rectangle-semicircle with two different heights have been evaluated. Simulations have been carried out in the platform of computational fluid dynamics and in Ansys Fluent software. Two-phase solid-gas flow including a sand flood and wind flow has been passed through the models and the amount of sand volume fraction has been compared. The results show that the rectangular-semi-circular geometric section (height of 20 cm) shows more favorable results against the influx of quicksand.

Considering that the issue of choosing the passenger's route and the parameters involved in it has been the focus and study of transportation planners and policymakers for decades, in this article it has been tried to increase the computational efficiency and reduce the data processing time by examining and improving the mathematical model of passenger route selection in previous studies. This issue has been addressed through multi-core data processing (parallel processing) based on the modification of mathematical models presented in previous studies in the form of a public transport dynamic assignment model with the shortest path algorithm based on the schedule and the travel elimination sub-algorithm. The results were compared with the outputs of a non-dynamic model based on the shortest link-based algorithm to measure the effect of considering the capacity constraint and dynamics of the algorithm on the calculation time and the accuracy of the output. Even though the number of calculations went up by 13.7% compared to the basic model, the time it took to solve the problem went down by 20% because of parallel processing.

The durability assessment of geosynthetics in the separation, filtration and drainage applications, leads to determining the service life of the product. For geosynthetic reinforcements, it is necessary to determine the long-term performance and estimate the strength reduction factors. The strength reduction factors and the service life of the geosynthetics are determined based on the type of polymer, short-term characteristics and long-term behavior of these materials under the effect of environmental conditions and loads. In recent years, several accelerated methods have been developed to evaluate the durability of geosynthetic products and several studies have been conducted to assess the durability of these products against a variety of chemical and mechanical deterioration mechanisms.In this paper, the concepts related to durability assessment, determination of service life, parameters affecting the durability of geosynthetic products, environmental conditions causing deterioration and various chemical and mechanical mechanisms of deterioration (weathering, oxidation, hydrolysis, creep, installation damage) have been reviwed. In the end, methods for determining the long-term strength and service life of geosynthetics used in road construction projects depending on their application, polymer type and environmental conditions are explained.

In this study the effect of PET content and particle size on resilient modulus and fatigue property of asphalt concrete has been investigated. PET was added to the mixture at different contents of 0, 2, 4 and 6% (by the weight of binder) with two different sizes as fine and coarse particles. The mixtures were subjected to resilient modulus test at 3 different temperatures of 5, 25 and 40°C and strain controlled fatigue test at 20°C. It was found that the samples containing coarse particles have similar trend at different temperatures, in which, the resilient modulus increases with increasing PET content. Similarly, in the mixtures containing fine PET particles, at 5°, the resilient modulus increases with increasing PET content. However, at 25 and 40°C, the mixture containing 2% PET has the highest resilient modulus with values of 3.5 and 0.808MPa, respectively. The mixtures containing fine particles have higher fatigue life and lower flexural stiffness than the control mixtures. In the mixtures containing 4% of coarse particles the highest flexural stiffness and lowest fatigue life, with the values of 3803MPa and 16260, respectively is obtained. The highest fatigue life for both fine and coarse PET particles is obtained with 6% of PET content, which are 100000 and 63250, respectively. It is concluded that the resilient modulus of the mixtures containing coarse particles is higher than the mixtures containing fine PET particles, but, the mixtures containing fine PET particles have higher fatigue life than the mixtures containing coarse particles.

Today, the use of new materials to improve soil bearing capacity is widely used. One of the new materials used in this field is geosynthetics. In many cases, standard solutions in geotechnical engineering to improve the ability and properties of soil are not practical. They need to use materials with easier access, lower cost, and better performance. From this research, the effect of different types of geosynthetics and the application and optimal use of these new materials in geotechnical engineering in various projects such as foundations, pools, embankments, bridge bridges, and roads. In this research, reviewing previous studies on geosynthetics, including numerical, laboratory, and numerical studies, an overview of the benefits and applications of these materials in civil and road engineering has been made. The research results show that geosynthetics in Increasing the bearing capacity and improving the strength properties of the soil have many applications and are also more economically justified than other methods of soil improvement.

The road networks of Mazandaran province are one of the most important road transport routes in the country. Transportation systems are the backbone of Disaster management measures, and maintaining their dynamics and performance in times of disaster is of particular importance for the continuation of rescue and response activities. In spite of the significant role of these systems in times of disasters, these systems are very vulnerable to the occurrence of disasters, and with the occurrence of natural disasters, their performance is disrupted and rescue activities are affected by it. Considering the necessity and importance of road networks and their very important role in disaster management, in this research, the investigation of road networks in Mazandaran province has been done. This study has been carried out in an analytical-descriptive method. a total of 216 points have been collected in all road axes of the province, and studies of tunnels, technical buildings, and bridges have been carried out, and in the GIS software environment, analysis and processing and priority It is framed. Based on the results of this research, according to the investigations carried out in terms of the existence of an alternative way for the bridges of the province, 11 of the bridges of the province have an alternative point way (optimal condition), 13 of the bridges of the province have the possibility of constructing an alternative way with Reasonable cost and the number of 192 bridges in the province lack alternative ways and also the impossibility of constructing them.

Accidents impose irreparable costs on the economy of countries every year. In addition, many of the death statistics are related to accidents, which can endanger the human factor itself, which is the driving factor of the economy. In the meantime, one of the road users who is very are exposed to accidents, it is the motorcycle riders who every year include a large part of the dead and injured in the accidents, the main purpose of which is to investigate the variables affecting the accidents of motorcycle riders. Collecting information on accidents as well as using various statistical and modeling methods such as Friedman, Aamili, Logit model and neural network to investigate the effect of each of these variables. The results showed that the variables of accident season, cause of accident, road surface conditions and lighting conditions had the highest rank respectively. On the other hand, the variables of the day and season of the accident and the age of motorcyclists, respectively, had the least importance in the occurrence of motorcyclist accidents on the roads of Gilan province. In addition to these variables, weather conditions, road surface conditions and lighting conditions were the first effective factors in the accidents of motorcyclists in Gilan province; According to the logit model obtained from the accidents of motorcycle riders, it was found that the variables of spring season, 6 to 12 and 18 to 24, dry surface conditions, night lighting conditions without sufficient light; rainy weather; Failure to pay attention to the front and sudden change of direction increase the possibility of accidents of motorcyclists on Gilan road crossings. based on the neural network model; The values of cause, lighting conditions and weather conditions respectively have the greatest effect on the severity of motorcyclist accidents on Gilan roads. Also, the neural network model with R2 values of 93.31 showed higher accuracy than the logit model.

The structural health monitoring of the infrastructure before and during the operation allows the supervisors to detect damage in concrete structures in the first stage of damage initiation and help the society economically and sustainably. This article investigates pavement surface and subsurface monitoring methods using piezo-resistance sensors inside the concrete. At first, self-sensing concrete sensors' damage detection mechanisms were studied and investigated for different loading conditions. Next, the article focused on the reviews of several methods developed based on the piezo-resistive properties in concrete to evaluate the level of damage. These methods, such as fracture mechanics, sequential electrodes, resistor mesh model, and tomography methods, were considered in this research. In the end, the tomography method used to detect crack propagation in a concrete pavement under an accelerated loading test in the real-world example was investigated. The results showed that the tomography method could accurately detect damage even from the subsurface of the concrete pavement when the damages come up to the surface. Therefore, the accuracy and prediction of such methods will be the key to developing smart infrastructure and future ways.

Grade-separated junctions (grade separations) play a significant role in increasing the utility of traffic parameters in urban transportation network and they are considered as the most important transportation infrastructure in all paths especially in urban streets. Once the conditions for the construction of a grade-separated- junction is met and the economic justification is provided, one should choose one of a variety of grade separations including overpasses or underpasses. This research evaluates the factors influencing the selection of underpasses and overpasses at intersections (Case study: Shahid Kharrazi Highway junction with 45m Shahid Bagheri and Arghavan Blvd). This study is applied in terms of purpose, survey in terms of data collection and quantitative based on the nature of data. The statistical population of the study consisted of technical and professional people in traffic such as transportation and traffic engineers in Tehran's 5th and 22nd district municipalities who were selected randomly. In this research, the required data was collected using a researcher-made 13-item questionnaire. To examine and test variables, hierarchical regression was used with SPSS software. Regarding the results of the regression equations, the variables are classified into three categories in importance. Accordingly, if , the grade separation is an underpass, if , the grade separation is an overpass and the type of grade separation for is determined based on the experts of the civil and transportation sector.

During the last few years, the transportation industry faced several crises with virus pandemic. The measures which are taken by the countries to tackle the pandemic has negatively affected the supply chain. It leaves the maritime transport industry with a vacuum of correctly predicting the volume of operations. The current research is an attempt to reduce the research gap and help market players to make more correct decisions in the future crisis. The purpose of this research is to model the time series of container transportation to predict the short-term trend of these indicators and its relationship with Covid-19 as an epidemic virus. The impact of Covid-19 is examined by forecasting container traffic indicators in 70 major international ports. The modeling process has been done with seasonal moving average and exponential smoothing model. To evaluate the performance of the models, information evaluation criteria and measurement error are calculated and compared. The seasonal integrated moving average model was found to be the most suitable and better model for predicting container indices.

The use of microsurfacing layer can provide some good preventive characteristics for asphalt pavement surfaces. Various additives can be used to improve the properties of microsurfacing layers. One of these acceptable additives is latex adhesive. It is claimed that latex adhesive as a polymeric material can withstand environmental factors such as alkaline conditions, acidic conditions, the presence of leachate and oil spilled on road surfaces. In this study, the effect of using latex adhesive in different amounts (4 and 5 %) on wet adhesion properties, setting time, compatibility of materials, abrasion resistance in wet track abrasion and sand adhesion of microsurfacings have been investigated. For this purpose, laboratory samples with different amounts of cement (1.5 and 3 %) and bitumen (8, 10 and 12 %) were prepared and tested. The results showed that the use of latex adhesive improves the behavior of microsurfacing in different percentages of bitumen and cement.

This article tries to study the revealed events while presenting a picture of the situation of the road transport sub-sector to address the issue of public finance policy in this sub-sector. Evidence suggests that in the current structure of the institution in charge of road transport policy and planning, the cost of transportation in the country and transit risk compared to global values ​​due to lack of integration and coherence in decision-making and policy-making is high. In comparative terms, although the overall quality of infrastructure and the quality of roads in Iran is almost the same as the average number of Islamic countries, but in comparison with countries such as Malaysia, Qatar, Turkey, Azerbaijan, Saudi Arabia, Oman, Kuwait, Indonesia rank Has a lower. Also, in terms of logistics performance index, Iran, with a rank of 64, has a lower position than the mentioned countries. Therefore, considering the special circumstances prevailing in the country (the issue of intensification of sanctions and economic recession), it is necessary to implement the revised solution in the public finance of the transportation sector (both public and private) as an urgent and immediate action in the country. . In addition, it seems that the category of general road transport expenditures in the country based on the policy in the two areas of management and development of road transport is possible and can be implemented.

Abstract:Background: Formulation and implementation of the policy of the Road Organization is one of the necessities of the organization to reduce accidents caused by accidents and traffic problems. Policy means paths, policies and decisions The implementation of policy refers to the activities that it performs directly.Objective: Several factors lead to the failure to implement the policies of the road organization that the present study identifies and ranks these factors.Research Method: This research is applied and in terms of strategy, survey. The research community consisted of 12 managers of the Highways and Road Transport Organization of the country who were selected through non-random and purposeful sampling. Data collection tools are interviews and questionnaires and FMEA technique and fuzzy AHP and fuzzy TOPSIS approach have been used to analyze the data.Findings: Based on the findings, the effective factors in the failure of the implementation of the policies of the Roads and Transportation Organization of the country are: Lack of skills and expertise of managers and employees in the implementation of policies and incorrect attitude of executives towards policies.Conclusion: According to the research findings, it is necessary for the organization to pay more attention to specialization and meritocracy in selecting managers and policy makers and training and empowering executives for effective and optimal implementation of policies in the organization.

Road user satisfaction is one of the most important factors indicating the optimal transportation system of countries. The difference between the passenger's expectations and the actual performance of the services provided will cause the passenger to be dissatisfied and will cause him to turn away; Therefore, it is important to study the relationship between the quality of traffic services and the satisfaction of road users. The process of conducting the present study is fieldwork and with the help of a questionnaire. The criteria of tangibles, reliability, assurance, responsiveness and compassion and commitment (empathy) are at a significant level. By paying attention to the coefficients of variables that have a significant level, it is clear that the effect and role of the tangibles in the importance of passenger satisfaction is more than other indicators. As a result, the presence of the necessary physical equipment and facilities, sufficient tools and machinery, and visible and suitable asphalt surfaces play the greatest role in passenger satisfaction.

In recent years, polymer-modified bitumens have been used to produce asphalt mixtures with better resistance to grooves, fatigue cracks and heat cracks. Research in recent decades has shown that the use of polymers in asphalt mixtures improves their properties and delays breakdowns. The important role of pavement quality on the safety and comfort of road users and also reducing the costs of the operation period, has led researchers in the field of asphalt pavement to produce modified asphalt to increase its resistance and durability against traffic loads and various conditions. Defects in pure bitumen produced in refineries lead to premature failure of asphalt pavements. A variety of additives have been used to modify the behavior of bitumen, including a variety of polymers.Bitumen is one of the most important factors affecting the fatigue performance of asphalt mixtures.Polymer additives as modifiers of bitumen properties and finally asphalt mix have been associated with successful experiments and their basic performance is affected by the physical, chemical and rheological properties of bitumen.

In today's highly competitive markets, corporate executives are looking for new ways to make people aware of their products and improve their brand. One of these methods is social media, which has revolutionized the field of business and internet marketing. The purpose of this study is to investigate the effect of social media marketing on brand equity and customer response at Mahan Airlines. The present study is applied in terms of purpose and descriptive-survey in terms of data collection method. The statistical population of the present study includes Mahan Airlines customers at Bandar Abbas International Airport. The sampling method is based on the structural equation modeling method and is equal to the total items of the questionnaire. Therefore, the sample size was 385 people. Data collection was done through questionnaires that were distributed among 385 customers of Mahan Airlines at Bandar Abbas Airport, a total of 385 questionnaires were returned. In this research, SPSS software was used to analyze the data and smart PLS software version 3 was used to perform structural equation modeling and hypothesis testing. Findings of this study show that marketing activities on social media have a positive and significant effect on brand awareness, brand reputation, brand loyalty, brand association and perceived quality as components of brand equity and also social media marketing has a positive and significant effect on customer response. Finally, brand equity has had a positive and significant effect on customer response.

Today, the growing trend of accidents in roads and casualties are the result of loss of national capital. These factors and the expression of practical solutions can reduce the incidence of such incidents. Behavioral abnormalities in driving are considered as a serious problem in society. Lack of skills in vehicle control, fatigue, drowsiness and exceeding speed limits, road geometry and psychological and economic problems are the causes of accidents in the country. Investigating the causes of traffic accidents shows that in addition to learning and acquiring skills and experience in the control of vehicles psychological factors, stress and economic situation also have a special role in preventing accidents. In this study, the effect of psychological behavior of heavy vehicle drivers on Zanjan-Tabriz axis crash rate is investigated. The statistical population of this research is heavy vehicle drivers and the study area is Zanjan-Tabriz axis in 1397 which was done by questionnaire method using SPSS20 software. The results showed that the exhaustion parameters of fatigue and drowsiness, economic factors, road geometry and stress had a positive and significant effect on the rate of accidents.

The aim of this study was to introduce and apply the urban resilience approach to natural disasters, especially earthquakes, and strengthen the ability of people to deal with the risks of disasters such as earthquakes in Yasuj urban area.This study is applied in terms of purpose and descriptive-analytical in nature. The method of data collection is library and field study. Also a necessary tool in this regard is a questionnaire. Also, the necessary tool in this field is a researcher-made questionnaire for people and experts, and the number of samples in the citizens 'utilization section is 308 samples (according to Cochran's formula) and in the experts' work section, 35 samples (Delphi technique). In order to analyze the data from SPSS software (Cronbach's alpha tests, Pearson correlation, one-sample t-test and data path analysis) and using multi-criteria decision making methods in the form of forced hierarchical analysis (AHP) and Expert Choice software was used.The results showed that the variable of resilience was significantly correlated with the criterion variable (reduction of the effects of natural disasters) and was able to explain some of the changes in reducing the effects of natural disasters. Based on the linear regression test, the respondents of the resilience scale predict a 92% reduction in the variance of the effects of natural disasters. By decreasing the standard deviation unit in the resilience score significantly (p <0.05), the reduction score of the effects of natural earthquake disasters increases by 20.6 standard deviation.

the present study seeks to identify and prioritize the factors affecting competitiveness at both the firm and industry levels in the field of aviation. The theoretical population of the research is the managers and experts of Iran Air and the aviation industry. The sampling method was judgmental and based on the expertise of individuals. The present research is applied in terms of orientation and quantitative multi-method in terms of methodology. At this stage, 30 factors were extracted at the firm level and 25 factors at the industry level. Because the number of these factors was high, these factors were screened by Binominal test. According to the significance coefficient, 8 factors related to the firm and 7 factors related to the industry were selected for the final prioritization. In the next step, these factors were prioritized separately using the Aras technique. Factors with priority at the firm level are: the factors of expertise and skills of human resources used in the firm or company, the number and composition of the firm's transport fleet and the firm's resilience to environmental shocks. Factors with priority at the industry level are as follows: The degree of consensus of key policy makers on the core issues of the industry and its prospects, the required infrastructure and the limitations of technology transfer in the import of new aircraft. To validate the results, the effective factors were also prioritized by Codas technique. The results of the two methods were very close.

Risk management is one of the most important aspects of the project. Risk management includes various areas such as planning, identifying, evaluating and controlling risk. In construction projects, due to the fact that the process of project implementation is known before the start, first the project risks are identified so that in case of encountering them during implementation, principled and efficient measures are taken. In research and development projects; Risk management is used to improve project implementation process, cost management, increase project profitability and is effective as a scientific and effective tool to reduce risk and loss. One of the most common methods of risk identification is to use the Delphi method and consult experts and the project team. This study identifies the risks of the design phase of the research and development project of rapid cable structure design, for this purpose 313 risks identified in eight groups of general executive risks: structural, mechanical, geotechnical and foundation, then three proposed designs were developed according to the evaluation of the severity of the effect and the probability of risks, and eight designs were obtained. According to the results obtained from the risks, these eight designs with eight criteria of fast construction, portability, These two methods are among the oldest methods of multi-criteria selection. In the scoring method, the score is at the disposal of experts, but in the method of sorting designs, they are placed in order. Finally, the selected designs were determined according to the effective parameter of span length.

Ever-growing concern to protect the environment concentrated the attention of the society on the possible re-use of different agricultural and industrial wastes in road construction. This research study depicts the effect of using wastes like rice husk ash (RHA) and fly ash (FA) as a replacement of conventionally used hydrated lime (HL) as fillers in hot-mix asphalt (HMA). Primarily, the dense graded bituminous macadam (DBM) mix specimens were made in the laboratory with varying proportions ranging from 2% to 8% of HL, RHA and FA by following design mixes according to the Marshall method and compared the results with control mix as prepared by utilizing 2% HL. The performances of the said mixes were studied through the Marshall Quotient, indirect tensile strength and tensile strength ratio. Results of investigation show better performance of HMA with the addition of RHA and FA and also proved to be economical as the optimum bitumen content is reduced by 7.5% from that of control mix when added at 4% filler ratio. Further, RHA shows a greater affinity to the bitumen attributing the highest stiffening effect of the bituminous mastic droplets compared to that of other used fillers with good compatibility at the micro level by satisfying the essential criterion.