فصلنامه جاده
سال بیستم شماره 2 (پیاپی 71، تابستان 1391)

Nowadays، rural transportation sector is a main source of environmental depreciation in the forms of fossil energies consumption، greenhouse gas emissions، air، water، land and noise pollution. A general consensus to avoid such deficiencies through sustainable development approach has lead to a number of policies and plans in this sector. Obviously، one of the main requirements of this approach is the accurate measurement of the status quo and society state in the case of each of policies or plan implementation. This paper presents the most frequent 11 indices for measuring the state of sustainability in rural transportation through a number of researches. According to sustainable planning، the mechanism of adopting the indices is based on the interrelation of transportation and land use development.

Inspection and evaluation of box-girder reinforced concrete bridges has been investigated here. Moreover، the most common problems in bridge decks of this type have been described. Because of the complexity of this type of bridges، in both the design and the construction phases، applying proper and scientific inspection methods as well as identifying the points and areas of potential of damage and failure have great importance. On the other hand، each bridge inspector must be aware of the structural behavior and more time should be spent for the inspection of the critical points and areas. The paper begins with a short introduction about the different types of box-girder reinforced concrete bridges with more details in the construction methods and the reinforcement arrays. The inspector should first of all be familiar with this introduction. After that، a detailed discussion about the failure modes of these types of bridges has been presented. The results show، beside the visual inspection، using accurate inspection tools and taking special attention to the deck details and the points which highly stressed (e. g.، anchorage area for prestress cables) is essential. Also، special attention to the form and location of different types of cracking is decisive for the better selection of proper repair، maintenance and other remedial works.

Variation of bitumen useful properties after continuous heat and cold cycles is a weak point of this substance. The temperature of these heating cycles is effective on loss of properties too. Due to problems while transport، hauling and conserving bitumen from production to asphalt plant، the effect of heating cycles and bitumen heating temperature on properties such as penetration degree، softening point and penetration index should be considered. In this paper the mentioned effects were surveyed by performing penetration and softening point test on bitumen samples heated in various cycles and heating durations. The results showed bitumen properties loss intensely after heating cycles and went out of range which should be considered in designs. Finally six models to predict penetration، softening point and penetration index of 67/70 and 85/100 bitumen after heating cycles and in various heating durations were developed.

When new construction or major reconstruction is planned، the current practice is for a location and design engineer to select the interchange type for a given location. The engineer relies upon projected traffic data، right-of-way needs، environmental concerns، safety، and project costs to determine which interchange configuration will most efficiently serve the needs of a certain area. The purpose of this study was to develop guidelines to aid designers in the preliminary selection of the optimum interchange type at a location. This study will provide engineers a starting point to begin their analyses. It is hoped that the development of these guidelines will result in reduced costs، improved levels of service، and increased uniformity. The literature review was performed in order to synthesize the findings of earlier studies on interchange selection. Information on interchange type selection processes was reviewed، and the relative advantages and disadvantages of the various interchange types were explored. A number of sources were used to develop the guidelines. A literature review helped determine current methods for interchange selection. These review also assisted in determining the relative advantages and disadvantages of the various interchange types. In terms of assessing the best pattern for interchange Getram software selected and various types of interchanges modeled. To discover the total performance cost of each pattern an index developed and by calculation of this cost index optimum interchange types were rated.

Every year in Iran large sum of money is spent in road improvement. Due to this fact that these costs are lower than the required credits and existing projects، the optimum distribution of credits and choosing the prioritized projects are of great importance. Therefore، if they are performed in a logical priority، the maximum efficiency can be gained from credits and performance of annual plans. It is clear when the number of existing alternatives exceeds the few، the issue is not just considered qualitative and all of the parameters must be converted to the measurable، thus the evaluation and comparison of parameters will be possible. Hence، the necessity of presentation of a method which can determine the priority of the projects'' performance through impressing index and parameters. The east corridor is one of the most important country''s routes in which the most part of passenger and freight exchanges is being done (especially freight transport). This corridor comprises of some routes with definite origins and destinations which one have their special physical conditions. The simultaneous improvement of all of these routes is not possible because budget is limited. In this paper، a method is developed to prioritize existing routes in the east corridor، using buffer analysis in ArcGIS9 and a mathematical linear integer programming model as a knapsack problem. Different sections of the axis are prioritized based on this model. The cost and access to the economic، social and service units are the parameters being used in the buffer analysis. The results of the model are acceptable in comparison with traffic statistics and expertise views.

With an increase in traffic volume and speed of vehicles on highways، the number of accidents has also increased. Reduced pavement friction between a vehicle’s tire and the pavement surface in wet weather conditions is the primary contributing factor in many accidents، and wet pavement friction is considerably affected by the range، which is based on the microtexture and macrotexture of the surface. microtexture and macrotexture are functions of the aggregate gradation type، and therefore one way to increase the skid resistance is use the best gradation features. This research is based on two stages. In stage I، twenty five asphalt core samples from a site in Iran were selected، and the microtexture، macro texture، asphalt content and gradation were measured for each. The British Pendulum Test (BPT) was used to quantify the microtexture، and a sand patch test (modified for laboratory use) was used to measure the macrotexture in terms of texture depth. In stage II of the study، four gradations in the range from the previous stage were selected and optimum asphalt contents determined. The microtexture and macrotexture of the four gradations were measured for the optimum asphalt contents. Results showed that the S-shape gradation proved to be most effective for improvement of the skid resistance and it can use in design process of asphalt.

In comparison with other industrial pavements، design and construction of port pavements need to consider several factors. Ports are often located on the lands with weak sub grade soil and should with stand a wide range of heavy vehicles compared to other pavements. Type of port pavement has an important effect on pavement durability and on budget requirements for construction، maintenance and rehabilitation. In this paper different alternatives for construction of port pavements were investigated and compared based on initial cost required to build each one. For this purpose، according to six different traffic volumes and using the method which is presented in new guide of design، construction and rehabilitation of pavements of Iranian ports different types of pavements including asphalt pavement، concrete block pavement، Portland cement concrete pavement and rolled compacted concrete pavement were designed and compared to each other based on initial cost construction. The study shows that the most economical pavement section which is feasible to be constructed in Iranian ports based on current cost of materials includes a rolled compacted concrete (RCC) surface، a cement treated base، a granular base and a capping layer.