نشریه فناوری حمل و نقل
پیاپی 32 (بهار و تابستان 1398)

Asphalt rural roads provide effective access to villages and as a network they play an important role in the development of these areas. The proper use of these roads as a basic infrastructure, is a very important factor of development. One of the important strategies in operation of these roads is the observation of standards and criteria of the asphalt pavement in terms of its effect on traffic safety. In this study, first, all parameters affecting the safety status of rural roads in terms of compliance with criteria and standards have been studied and then by using hierarchical analysis (AHP) to obtain the opinion of relevant managers and experts of the Ministry of Roads and Urban Development, the weight of asphalt pavement condition has been extracted and then using GIS software capability and also using the capacity of safety experts of all road and urban development departments, all rural asphalt roads in the country with a length of 105,100 km in 1393 have been audited and the results of the analysis were analyzed.

Abrupt and non-uniform changes in track vertical stiffness in railway bridges transition zone, increase dynamic loads, asymmetric deformations and track components damage and as a result, it increases maintenance costs. In this paper, the most widely used methods for stiffness transition are investigated, including concrete approach slab, hot mixed asphalt layer, stabilization and improvement of transition zone embankment. Then, the innovative combinatorial methods including improvement of transition zone backfill (embankment) materials with resilient pads under sleepers and rails on the deck based on specific criteria according to the finite element model. The results show that despeite various stiffness transition methods, the track according to the rail vertical displacement, ballasted layer vertical displacement and stress in the middle of the subgrade layer states has more desirable behaviour by about 14 to 22 percent, 3 to 29 and 4 to 36 percent respectively, rather than there is no stiffness transition in transition zone. Based on dynamic analysis, rail dynamic vertical displacement, rail dynamic vertical acceleration and force in subgrade layer is decreased by about 11 to 17, 32 to 40 and 1 to 22 percent respectively. Finally it appears that a combinatorial transition method include improved embankment in transition zone with resilient pads under the rail for rail on deck improved track behavior based on the criteria the rail vertical displacement and ballasted layer vertical displacement about %31, also decreased the normal stress in the middle of the subgrade layer approximately %28 and based on dynamic analysis, rail dynamic vertical displacement, rail dynamic vertical acceleration and force in subgrade layer is decreased by about 21, 34 and 23 percent, respectively. This method can provide the best impact and performance between different methods for concrete short span bridge and the relative displacement reduced in transition zone from 0.55 mm to 0.11 mm.

The lack of using experience and opinions of the people in decision-making of a public project, leads to failure in obtaining public satisfaction. This is due to ignoring the suggestions of the people, especially the deprived of transportation, and not knowing their real needs. Citizen participation is the best strategy by which the essential needs of the people can be informed and their opinions and experiences can be included in the decision-making process. The Urban Planning Organization, while informing the public about the holding of these partnerships, should provide full access to this process for all segments of the society, especially those who are deprived of transportation, in order to easily participate in these communities. In addition, this access must be provided to citizens so that they can express their opinions and be effective in making decisions. Achieving such effective public participation requires adequate infrastructure, including citizenship advisory committees, public relations, and applicable laws. The application of these infrastructures in this process should be done according to a model so that the people's participation is implemented in the best way, including all the goals and has the highest efficiency. In order to achieve this goal, a six-dimensional model is proposed, which by examining the previous models of public participation and adding steps to them, will improve the implementation and effectiveness of this social process.

Generally, the earth was initially influenced by pressure from natural stresses and any disturbance such as tunnel boring has disrupted such a stress situation and causing the displacement in the ground. If such displacement is not in the standard area, it may cause problems in the surface and sub-surface structures, and occasionally followed by many damages. Boring the tunnel in the earthy grounds may develop horizontal and vertical displacement surrounding the tunnel. Such displacement might attain to the surface of the ground and damage the existing structures on the surface; thus, this study investigates and calculates the effect rate of any geotechnical parameters of the soil such as contraction of the tunnel section, placement depth and distance of the tunnels from each other. According to the results, by increasing the contraction of the tunnel section, the ground subsidence has been increased and by increasing the diameter of the tunnel, the ground surface is initially inflated and then subsided. By increasing the placement depth, the ground subsidence will be initially increased and then in the lower depths it will be reduced and by increasing the distance between tunnels in the twin tunnel, the surface of the ground has been inflated. The obtained results have been explained more by using the tables.

Earth slope stability is one of the main issues on which researchers all around the world focus on and various methods proposed in order to reinforce slopes (both natural and man-made). There are lots of approaches for stabilization of slopes, among which using a row of stone columns (or piles) is the most effective and economical method in order to stabilize and reinforce earth slopes and road embankments. Researchers have used different numerical and analytical methods for optimal locationing of stone columns or piles for stability enhancements of earth slopes or road embankments, which were resulted in different outcomes. This issue brings the question that, where is the optimal location for inserting these structural elements? It seems that laboratory analysis and modeling in this issue is missing. In this paper, the problem is examined by laboratory modeling and optimal location of stone columns and piles as reinforcing elements in earth slopes and road embankments investigated and the results are compared.

Road and Traffic signs are useful measures for providing road user's safety and traffic management. The Colors used in Traffic signs also have an important role in proper understanding of the concepts and functions required along the routes. In the present article, the signs in the two sections of suburban and inner-city roads with the international guidelines (1968 Vienna Convention and the standards of Germany, England and the United States) are compared, and the scientific and psychological reasons for using different colors in traffic signs are examined. Then, what is being wrongly formed in the country's roads and does not comply with international standards and the psychology of colors, and may in some cases cause anxiety in the mind of the driver and even accidents, will be reviewed and executive solutions are presented.

The use of asphalt in paving BRT lines in Tehran, due to heavy axial loads of passing vehicles and heavy braking force caused by these vehicles, has led to various pavement failures such as reflective cracks, grooves, shrinkage, longitudinal and transverse cracks. In this paper, a model of conventional concrete pavements is compared with models of new materials such as fibrous concrete, permeable concrete and fiber permeable concrete using Abaqus and Kenpave software in paving BRT lines in Tehran. Laboratory results have been used to calibrate the modeling parameters. At the end of the article, the effect of repetitive loading on tensile fatigue behavior in concrete models is discussed. To generalize the results, light cargo and A380 aircraft were also used. Compressive, tensile, deformation, and von Mises stress diagrams were obtained by applying these loads to models with a thickness of 5, 10, 15, 20, and 25 cm. The results showed that by controlling the tensile and compressive stresses applied on the surface and also applying one million loading cycles on it, all the mentioned materials can be used in road pavement and fiber concrete in airport pavement.