پژوهشنامه حمل و نقل
سال چهارم شماره 2 (پیاپی 11، تابستان 1386)

The main reasons of injury and death all over the world and especially in Iran are mainly run off road, roll over, and crushing with the fixed objects at the roadside. This is why the road safety engineers should pay special attention to roadside hazards, otherwise as a consequence the number of fatalities would increase consequently although exact data are not available regarding this issue in Iran, evidence shows that a large number of dangerous road accidents in Iran is due to vehicle run-off-the road. Nowadays introduction of a model which would have the capability of anticipating the number of run-off-roads would assist the engineers to evaluate the number of run-off in order to carry out a proper incident management In this research a model has been introduced that is capable of anticipating the number of roll-over due to run-off-roads in each direction of roads. The effect of each parameter has been thoroughly investigated on the roadside safety, and finally its effects on the number of accident occurred in Iranian Roads. In this research, two models for prediction of vehicle run – off - road were evaluated.For evaluating the differences between the obtained amounts by selected models and the real rates for the run off roads, the X test was used. This test was chosen due to the quantitative characteristics of accidents (which are usually numbered) and the real amount of run-off- road also due to the number of accidents in each direction of roads and the fitness of theoric models. The following model had the most realistic similarities with the predicted rates and therefore was chosen for utilization. This model is shown below:ADT/1000000)×exp(βst-(0.04×ADT/1000)+lnf + 0.12HC+0.05VG) ×E=(365 Where:E = expected number of road side encroachment per kilometer annually.ADT = average annual daily traffic (in number of vehicles) from 1000 to 12000.B st = state constant with a default value of 0.45 for those areas (¬or states) where rural two- lane roads data are available, it is recommended that B st be estimated as the natural log of the run-off-road accident rate for road segment with low ADT (e.g., 2000) that are relatively straight (e.g., horizontal curvature < 3 degrees) and level (e.g., vertical grade < 3%). Lnf= 0, 0.20, and 0.44, respectively, for road segments with 3.6m 3.3m 3 m ft wide lane.HC = horizontal curvature) for 0 to 30 degree. VG= vertical grade (in percent) from 0 to 10 percent.Using the above model it would be possible to predict the total run off road accidents. On the other hand, the main objective of this research is estimating the amount and percentage of rollover due to run off roads. Due to this fact it was tried to consider an index namely Roadside Hazard Index. By using this index the above objective may be achieved.Using this index which is always >1 it would be possible to estimate the rollover due to run off roads, as follows:The road side safety condition is depended to RH index.RH = the length of risk ratio to the length of axis: Therefore by considering RH index in choosing the model, ¬the number of rollover due to Run-Off-Roads is resulted as follows:ADT/1000000)×(RH)×exp(βst-(0.04×ADT/1000)+lnf + 0.12HC+0.05VG) ×E= (365 The roads network including 5 axes was chosen and based on the road side accidents occurred in this direction of roads¬, the amount of index was estimated. This model was finally designed by comparing the result of the above model and the real amount of it (due to X2 test).Conclusions of this research project are as follows:It is considered that 30 percent of road accidents in the whole country are caused by run off vehicles from roads and about half of this 30 percent are concluded to damaging of vehicles.-Comparing the predicted amount to the model and the real numbers in the year 2004 shows that the difference between models is about 26 percent in average.At the Gonabad network (in north east of Iran), investigations showed that in this network, the non standard and critical road side gradients as the road side hazards and cause the rollover of the vehicles from the road. Considering the conditions of the country it may be concluded that the Roadside Hazard Index for the whole network is 41%. By other words it is said that the 41% of the total run off road is resulted to rollover.

The estimation of urban trips generated by each traffic zone in future is a crucial stage of urban transportation planning. In trip generation models, the relationship among the socio-economic characteristics of the region under study, the land-use features, and the transportation demand is analyzed. In order to predict the rate of trip generation (number of per capita or household trips generated), regression models are widely used. These models have been introduced based on theoretical framework of econometrics. However, cross-classification table is an alternative simple approach for predicting these rates. In this method families are categorized based on their common characteristics. The tables that are used for future prediction can be classified based on different trip purposes. Cross-classification tables can be used in two or more dimensional layout. In a two dimensional cross-classification table, the rate of daily trips produced per household is estimated for the categories created by only two variables (generally household size and car ownership). In multiple cross-classification tables, more than two (generally three) variables are used to categorize the people in different groups (table cells herein) and then estimate the produced household trip rates. In this paper the three variables are household size, car ownership and density. Like any other model, matching the reality (having reasonable rates herein,) is a main problem during the model development. The traditional method of trip rate adjustment in a cross-classification table is the ANOVA method. In this method, the rate in each table cell is modified by the average deviation of the relevant row and column of that cell. Although this modification to some extent improves the calculated rates, it does not necessarily lead to reasonable values comparing with neighboring cell rates.The trip rates for each category are achieved from the observed data. Sometimes these calculated rates do not show the expected trip pattern. For example a single man (as a one person family) without a car, that seems to have less trip rate than a five person family with two cars, has a more rate. Therefore, this irregularity should be modified. This paper uses fuzzy linear programming method for adjusting the values of the multiple cross-classification tables. In this method the understanding and judgment of experts is applied to make the adjusted rates as close as possible to the reasonable values. In this method, trip rates of table cells are modified using the relations and the constraints that are obtained from the exceptions of transportation analysts regarding trip rates. The resulting fuzzy models are solved using “LINDO” package software. Comparing the results shows that there is no significant difference between the rates before and after adjustment for each density category. The total number of observed trips differs from that of adjusted trips only about %5 on the average for the three density categories, which is acceptable. As seen, this method modifies the rates for each category simply and reasonably. In order to compare, and to show the reliability of the proposed method comparing to the ANOVA method, the coefficient of determination (R2) is used too. The achieved coefficients reflect the same results as above. The paper is organized as follows: First, the multiple cross-classification model is introduced. Then the problem is defined and the principles based on which the rates are adjusted, are explained. Then the study uses real data from Mash had Transportation Comprehensive Study in order to reflect the influence of the proposed method comparing to traditional ANOVA method. Finally, the results, conclusions and references are presented. The acquired results show that fuzzy optimization method works better than analysis of variance method for multiple cross-classification tables.

As the availability of the road surfacing material, manpower and financial resources become limited, it would be very costly for most of the countries to afford the costs of high quality aggregates [in terms of Polished Stone Value (PSV)] to be used in high frictional demanding locations. It is often believed that the Polished Stone Value of aggregates depends on the process of crushing aggregates. This paper describes a laboratory assessment of the potential for increasing aggregates Polished Stone Value (PSV) of aggregates by adopting simulated methods of crushing aggregates, thereby up-grading Polished Stone Values of lower grade aggregates. The main objective of the work has been to investigate performance in the laboratory condition of aggregates subjected to a mechanical treatment (simulating crushing) to create rougher surface texture to compare with their naturally crushed state, with a view to establishing the suitability of the material to benefit from the type of treatment adopted. Applied methods give a different surface texture from its usual method of crushing, methods adopted are mechanical re-texturing techniques which creates different surface texture in a controlled laboratory condition.Road stone quarrying is the multistage process by which rock is extracted from the ground and crushed to produce aggregate, which is then screened into the sizes required for immediate use as chippings etc.. As far as the Polished Stone Value (PSV) of the aggregate is concerned, the surface of the aggregates roughness which is in contact with the tire is important in the process of aggregate processing, therefore, analyzing different textures of the same aggregate surface is the main objective of this paper. To serve the purpose, an apparatus has been designed and developed to carry out re-texturing of aggregates, using methods which apply needle gun and sand blasting. Aggregate have been arranged according to their Petrographical group classification. Tests have been carried out on more than 300 samples made from 35 quarries under controlled laboratory conditions. Samples were assembled and test specimens were made in accordance to the procedures described in BS 812 Part 114, 1989.Initially, the Unpolished Stone Value (UPSV) of samples have been taken by British pendulum, then, Polished Stone Value (PSV) of each aggregate samples ware measured in a programme of standard tests. The test specimen was subjected to a program of the re-texturing treatments. Pendulum value of the treated samples has been taken (UPSVR). Treated samples have been assembled in a program of testing on accelerated polishing machine in order to assess re-textured polished stone value (PSVr) of aggregates according the BS812 Part 114 1989. As some aggregates have undergone re-texturing treatments it has been established that some end up with significantly higher in performance in terms of their re-textured pendulum value (USVr), and above all, their polished stone value (PSV) than others. It was found that Per graphical group classification have little to no effect regarding the final outcome of the up-grading aggregates PSV procedure. Therefore each aggregate must be considered in the light of its own individual properties and characteristics.

There are different methods for allocation and prioritization of land use to regional area. These methods of allocation and prioritization may be divided into two different principle groups, namely quantitative and qualitative groups. In Iran, qualitative method is mostly used due to rather complicated accessibility either to collection of statistics or to available facilities. In the present paper, every effort has been made to propose a quantitative model to allocate land uses to regional area with regard to the existing statistics and facilities. Also, in order to define the place for different land use concepts such as land suitability which indicates quality grade and suitability of each land (cell) for variety of uses, added value of each land for different uses, as well as the distance between each land and population centers have been used.Having studied the above mentioned resources and present study objectives, as well as available facilities, some land uses as per the following classification are selected:- Compulsory land uses,- Environmental preservation land uses,- Exploitation land uses,- Other compulsory uses that have been determined in advance for the regional lands,- Optional land uses,- Industrial land uses,- General constructed land uses,- Agricultural and range management land uses,On the present studies if lands are recognized bearing compulsory uses requirements, these lands shall be put aside and therefore any special estimation and modeling shall not be performed. In this way the optional land uses section, the subject of the present paper, the optional uses have already been allocated and the input information is considered a part of the present model. In these studies industrial land uses including all activities in manufacturing category presented through International Standard Industrial Classification (ISIC) or all activities called “INDUSTRY” in Iran statistical yearbook. General constructed land uses are those activities not included in other land uses and they need construction and building, such as universities, research centers, stadiums, cemeteries and warehouse. Then, a relation is set up to determine adjusted land suitability of each land for each land use set forth in the paper. Where - Adjusted land suitability score of land number for land use, - Land suitability score of land number for land use, - A variable that indicates Relative value added of land use in one acre in an acre - Accessibility Index land number for land use (), - Time distance of land for land use in terms of hour, - Constant value, it will determine in calibration phase. - Land number, - Land use number.The main objective is allocation of different land uses to regional lands can be defined in mathematical terms if the total lands suitability is maximized and land uses required by national and regional policies are provided. The optimization model is a linear programming model. The simplified form of this model can be expressed as follows: Subject to: Where - Total adjusted land suitability, - Adjusted land suitability of land for land use, - Number of land uses used in the studies (= 1,….,) - Number of lands in the region (= 1…): If in land allocate to land use, : If in land don’t allocate to land use, - Number of lands allocated to land use in the region according to regional policies - Land number, - Land use number.Having introduced the present mathematical model, probable estimation of changes of future land use in the vicinity of city, and also, study of land use status in the vicinity of new towns have been provided. In order to display output and capability of the proposed model, a hypothetical sample is presented in this paper.

The additional costs generated when an additional train uses the Railway infrastructure is defined as the marginal cost of usage of the network. This index can be divided into five main types: use-related infrastructure wear and tear costs, congestion costs, scarcity costs, external accident costs and environmental costs. Wear and tear of railway track is caused by a combination of usage-related and environmental-related damage. Use-related wear and tear costs are that proportion of the inspection, maintenance and renewal costs which result from trains using, and hence causing damage to, the track.The main goal for this research is estimating the marginal costs for utilizing the Infrastructure of Iranian Railway Network. As an important economical index in rail operations, the marginal cost can be applied to determine infrastructure access charge as well as the freight and passenger tariffs in Iranian railway transportation. In this research, we focus on use-related wear and tear costs for Railway infrastructure marginal cost. This research identifies the variables transported grass-ton, maximum track slope, and maximum line speed as the principal cost determinant and based on the five years averaging of track maintenance cost observations of the twelve Iranian rail sections during the years from 2000 to 2004 cost elasticity with respect to grass-tons is 0.161 and the marginal cost equals to 0.12 Euro per thousands grass-tons. In this research it is assumed that marginal cost doesn’t change with increase in length of lines. This paper is organized as follows: section 1 presents an introduction to marginal cost and its role on the privatization as well as access pricing of the networked infrastructures. Section 2 reviews models and approaches to estimate marginal cost. In this section, a definition for marginal cost of utilization of the railway infrastructure network is presented. Section 3 illustrates the data structure that is used for modeling the Iranian railway network. The identified model and causal variables contributing in the Marginal cost estimation of Iranian railway network is presented in section 4 of the paper. This section includes a comprehensive review of the cost functions adopted by Austria, Sweden, and Finland Railways. Pitfalls and strengths of the fun cost functions are investigated and results for Iranian Railway network is compared with those of the selected countries. Section 5 concludes the paper and consist of some suggestion for further researches.

Retaining structures, as a part of road transportation systems have sometimes a great affect on the total cost of construction in our highly seismic risk country. Accordingly, studying the lateral earth pressure during earthquakes is very important to provide and economical and technical design for retaining walls. Mononobe-Okabe method is one of the first theories proposed to determine the seismic lateral earth pressure and is still in use by geotechnical engineers and designers. M-O method is a seismic version of coulomb theory and based on pseudo-static earthquake loading for granular soils. This method applies earthquake force components by two coefficient called seismic horizontal and vertical coefficients. The M-O method is essentially a closed form solution based on some simple assumptions which supply relationships to calculate both active and passive pressures. The assumptions can make the problem too simple to be used by engineers, but in many cases is not applicable to the real cases which put it mostly far from having a safe or economical design. Simple geometry of backfill material, disability to consider the cohesion of soils and water table are some of its disadvantageous. The aim of this study is to remove the limits and to cover other problems that M-O has no answer for them. In the proposed method, in addition to soil cohesion, the interface cohesion between soil and wall material is included. The crack depth in ground surface for the case of cohesive materials of backfill can be also considered. The study is headed back to the fundamental theory of Coulomb and benefits from an iterative calculation of forces diagram of failure wedges to overcome the limitations encountered in M-O method.

Nowadays computer technology provides different ways to check technical and economical study of DC traction supply systems projects. It is quite possible to simulate the rolling stock transportation based on operation program, also voltage and current calculation and determines the rectifiers and inverters outputs in every moment and position and also it is possible to check the rectifier substation proposed positions.The estimated passenger number, operation program and passenger comfort are necessary parameters in rolling stock selection. It is possible to determine rectifier output in normal and one transformer rectifier unit out of service condition. As well calculation provides the information of energy consumption and rail voltage regarding the earth.Rolling stock data is needed for calculation and simulation. As an example it is necessary to know motor specification at motoring and braking condition, its weight and also track data such as gradient, curve and maximum speed. All contact line, current returning circuit, substation place and operation program data must be defined.The first step to simulate traction supply network is simulating the train dynamic movement in order to specify the position, speed, acceleration and rolling stock power consumption. Therefore this topic was chosen for the present research.In this paper the dynamic train dynamics was taken into account. The train dynamics graph was presented as a key curve in determination of the number of existent trains in return lines and by the simulation process, the moment rates of mechanical parameters such as the location, the consumption rate of trains in each point of the line and the moment velocity of the return trains are presented.

In the past two decades the land subsidence and ground failures in Yazd province, especially in Yazd - Ardakan flat area caused many damages and failures in existing roads and structures. The visual appearance of failures are generally: large subsidence in road body in the form of wide and deep cracks, structural failures and cracks in walls and foundations, breakage in water and gas or oil pipe lines, over turning of electrical transmission towers, and appearance of deep cracks and holes in agriculture lands. This research was taken place in Yazd - Ardakan flat after few previous unsatisfactory investigations. In this research a deep borehole and four hand cut holes were drilled and visual investigations throughout the crack distribution indicated that the both external and internal phenomena caused ground failures.External PhenomenonThe topography maps of Yazd - Ardakan flat area indicate that the ground surface slopes are too small. As the area is arid with fewer rainfalls, rivers and surface water ways can not be created by flow concentrations. In most seasons a few millimeters of rainfall will evaporate or penetrate in ground without surface flow creation. In some cases when a rapid and a dense fall occur, there are no considerable flow ways for extra surface water. Therefore water will rise up in existence of low level grounds, creating natural pools, which their water will find holes to penetrate in ground as concentrated non-controlled flows. Investigations in ground of Yazd - Ardakan flat shows that there are old root holes in many cases which facilitate the concentration flows to underground portions. These flows erode soil and create holes with larger diameters. Due to these erosions, first radial cracks are generated around these holes, and then by extra erosions, circumferential cracks are added perpendicular to radial cracks. Internal phenomenonBased on laboratory tests, the ground soil is generally silty soil (0 to 95 percent silt). The silt particles are cemented by clay and salt. The water penetration test at site, showed that the soil permeability is too large compared to laboratory test results. The collapsibility tests in laboratory showed that the soil is collapsible in many cases. Dispersivity tests showed that the soluble salts in particle mid connections can be easily solved and it is enough to collapse soil. Based on the research results, some prevention and treatment methods are proposed. These methods may be described as; constructing artificial water ways, filling the cracks by soil cement mix and finally constructing the low dikes.By determining the failures mechanism, the repair and destruction prevention methods in roads, buildings and installations are proposed in this paper.