فصلنامه جاده
سال بیست و هشتم شماره 1 (پیاپی 102، بهار 1399)

Intersections are a factor in determining the capacity of the transportation network, and any disruptions such as accidents in them will result in a severe capacity reduction. Accident crashes at intersections are significant due to the convergence of traffic flows. The purpose of this study is to investigate the factors affecting fatal accidents. For this purpose, geometric, traffic, fatality and control status data of 65 intersections of Isfahan city were extracted and analyzed in SPSS22 software. This analysis was carried out using Poisson linear logarithmic modeling, negative binomial linear logarithmic and linear regression. The results showed the superiority of the negative binomial model to the other two models, and it was found that 5 variables including the number of phases at the intersection, the presence of the camera, the width of the line, the width of the left-turning lane and the straight transit volume, are among the variables that affect safety.

Skid resistance threshold (TL) is a method that is widely used in road pavement management as a minimum standard for activating the maintenance of each section of the pavement with less resistance to skidding than this threshold. Different methods are used to determine the threshold level of skid resistance in different countries (depending on their climatic conditions). Determining the precision of the skid resistance threshold is important, and its timely implementation will prevent many accidents. So far, various methods have been used to determine the threshold of skid resistance in different countries of the world, including: the three-point curve method, the statewide method and hierarchical tree grouping, etc. A single-point measure of skid resistance is not acurate to show the skid resistance performance on a surface of the pavements. Therefore, this major limitation of single-point models can be remedied using the two-parameter slip resistance models, the Peen State slip resistance model, the PIARC International Friction Index (IFI) model and the CRR-SN nationwide model. The NUS model is one of the latest models to be used more precisely for threshold determination. The application of each of these is analyzed in this paper.

In this study, investigate a statistical population division based on age, gender, education and time of getting the driving license. Seven hundred sixty-eight persons were asked perceptible, recognition-acquaintance questions about all traffic signs including regulatory, warning, and guide ones. Utilizing this method reveals both basic understanding of individuals and sign’s flaws. Moreover, it discloses the level of familiarity to signs in different groups of people and as a result, the best types of comprehensible traffic signs. In the following, through precise questionnaire look into the driver’s quality perception of signs in order to assess every single indication. Different groups of driver divided into age, education, time of getting the driving license and gender answer to questions, then SPSS software demonstrate valuable results. For instance, higher education has a direct relationship with better knowing signs while driving experience works inversely. Pearson Correlation Coefficient for the education term is 0.56 for right and wrong answers; it means more education increases right answers.

The projects that the Islamic Republic of Iran Railways, in the form of EPC, is entrusted to parent company companies are among the most important projects in Iran. In the meantime, the problems in the various phases of the project, including the engineering phase, the procurement phase, and the implementation phase, are very controversial in the project's main factors, such as project time, project cost, and project quality, and it is very important to provide solutions for them. In this research, after identifying delays in Iranian Railways projects, their hierarchical analysis will be applied to their prioritization. Usually many of the country's development projects are delayed, and these delays have many effects. Increasing project completion time, increasing project costs, not achieving the required quality, including the consequences of delay. These problems can cause disagreements between project stakeholders and all require time, cost and energy. Therefore, identifying and prioritizing delays in rail project projects is a prerequisite for the implementation of this research. The research gaps in these studies reveal the need for this research.

Compressive and tensile strength of intact rocks are very important to evolution of rock slope stability and tunnels analysis. The physical properties of rock such as porosity and density as physical parameters of the rock that affects strength, are of utmost importance. Finding a relationship between the physical properties and strength of rock may be innovative and easy method to estimate the mechanical strength of rocks. In this paper, conducting simple field tests and establishing relationships between them, it has been tried to present relations for replacing simple tests with costly and time-consuming laboratorial test in the field. The tests are conducted on 37 samples of magnetite iron ore with different densities for each test. Samples have collected Sarvian Mine, near Delijan. Then, the tests were compared pairwise in order to determine their effects and obtain their relationships. The experimental model was a relationship with 0.89 correlation coefficient.

The extension of used tunneling mechanized drilling machines (TBMs) in tunneling projects has led to the increased use of prefabricated concrete segments. The use of fiber concrete as a substitute for concrete reinforced concrete with regard to the improvement of concrete fiber performance and its cost-effectiveness is a subject in civil engineering. Arming reinforcements are effective against the stresses of concrete segments, such as concentrated forces that enter the segment during the construction process. On the other hand, fiber reinforced concrete is able to perform well against widespread stresses such as stresses caused by ground pressure and underground water. Due to the presence of both concentrated and extensive force, the pre-fabricated tunnel segments can be presented as a combination of reinforcement and fiber. In this research, according to the method presented in the ACI 544.7R instruction, the two-dimensional beam-spring modeling in the SAP2000 and the design of the structure of the tunnel under the transient loads and the segment's production stages, the transient loads in the steps Construction and permanent loads have been dealt with in the exploitation phase. According to the specifications of the project and the load applied to it, the concrete segment with 0.5% of the steel fibers alone was not responsive to the loads involved and the reinforcement was used to compensate for the resistance and the prefabricated concrete segment with the combination of reinforcement and steel fibers for designing it was proposed. Finally, the proposed model led to a 30% reduction in steel reinforcement consumption.

Form of the source-destination matrix Conventional approaches to accessing this matrix An essential input to the transportation planning process is the amount of travel demand in the directly, based on interviews and surveys in specific locations, are costly and time consuming. Hence, for the sake of mathematical methods based on intuitive statistics such as the volume of traffic in the network passages are becoming more and more popular in transportation studies. These methods are defined by having a source-primary-destination matrix as well as the current traffic flow information observed in a number of network paths, resulting in matrix estimation with the least distance from the primary matrix. , When allocated to the network, reproduce the observed volumes. Because conventional methods of obtaining this matrix that are based on interviewing and surveying are expensive, time consuming and annoying to people, the mathematical methods based on the observed statistics (such as the volume of network passage counts) ) Are expanding day by day. In this research, the source-destination matrix estimation methods can be divided into crowded and backbone networks in terms of network performance and the characteristics of each are presented.

Soil stabilization is a useful method for improving materials in pavement construction layers. On the other side, the increasing volume of municipal waste and residues materials especially debris of building destruction and urban exhausted tissues have caused many problems in mega cities such as environmental issues due to incorrect disposal of waste material.  Construction wastes in large urban cities show that brick and concrete are two main constituent materials. In this research, effects of clay brick aggregates on bearing capacity of clayey soils for application in pavement layers was studied. For this purpose, clay brick aggregates in 5, 10, 15 and 30 percentage mixed with clay. Also, for evaluating geotechnical behavior of mixture materials some tests were performed such as uniaxial strength, California bearing ratio (CBR), direct shear (in dry and saturate conditions) and falling head permeability. In saturate position, swelling potential of specimens was measured. Results of this study showed which add clay brick aggregates in clayey soil limited change in structure and texture of mixed specimens creates. So that, structure of aggregates mixture is inclined from fine to granular condition. Whereby, with adding 30% clay brick aggregates in clay, bearing capacity and permeability increased and swelling decreased. Also, with considering results possibility to use mixed materials in subgrade and subbase pavement layers have been prepared.

One of a variety of vehicles that plays a significant role in traffic accident in Iran is heavy vehicles. According to available statistics, more than 8% of whole traffic accidents has been created by heavy vehicles which accounting for about 15% of deaths from accidents. As well as according to current statistics, the reason of 70 percent of traffic accidents in Iran are human, so heavy vehicle drivers can be very effective in causing accidents. In this research, the main human errors of heavy vehicle drivers have been identified by determining the impact of each human error on the rate of accidents, then it is determined which error has the most impact on crashes, as well as the relationship between errors and the number of accidents. The statistical population in this study is heavy vehicle drivers and the case study region is the main road of Zanjan-Qazvin in 2018. The final results show that using a mathematical model derived from law non-compliance parameters, psychological problems and driver fatigue can predict the amount of accidents. In the other words, increasing or decreasing to one unit of the parameters can increase or decrease the number of accidents in the case study path.

Nowadays, with the increase in the number of vehicles on urban roads, a lot of interferences happen in the intersections. Therefore, it seems necessary to pay more attention to the construction or modification of the intersections, especially the interchanges, which have flourished in recent years. On the other hand, given the high costs of construction projects, it is essential to select an intersection in which its modification could address the whole network traffic problem adequately. The development and improvement of non-interconnected intersections with poor geometries and traffics not only improves the efficiency of the intersection but also improves the efficiency of the entire highway network. Therefore, in this paper, a method for classification and prioritization of the intersections is proposed to provide a more comprehensive vision for the planners and governments. This method helps them in the budget allocations and time priorities definitions of the construction or modification project efficiently. Herein, after reviewing the intersections, the TOPSIS method called is employed to analyze the Shannon entropy weights. Next, the geometric and traffic indicators are defined. Then, as a case study, the non-level intersections of Shahid Hemmat highway in Tehran (14 cases) are categorized and prioritized. The results show that a left-handed or right-handed protected intersection with the bandwidth of decrease and increase of the high speeds has a higher priority.

Forest Roads are the main element of recovering, conserving and harvesting of natural resources. The current research has down in order to spatial locating qualitative characteristics of road pavement and schedule conservation and maintenance projects in main road, 1, 2, 3 roads in ShastKalateh Forestry plan, Gorgan, Iran. First all of the roads were sampled 100% defects of Pave, Technical Buildings, Horizontal curve were recorded. As well as, Landslide and Erosion point that make the problem were recorded then restoration methods were determined. Results showed in pavement part, slump and vegetation cover on the travel way were the important problem of roads. In addition Landslide and Erosion and trees in Horizontal curve were the other dilemmas of the roads. Subsequently, annual and Periodic reconstruction schedules have been recommended. In addition Landslide and Erosion and trees in Horizontal curve were the other dilemmas of the roads. Subsequently, annual and Periodic reconstruction schedules have been recommended.