فصلنامه جاده
سال بیست و پنجم شماره 2 (پیاپی 91، تابستان 1396)

Installing effective warning signs are one of the road safety requirements that have used in order to better utilization of the existing roads and streets in every country. Thus, the colored asphalt in roads and streets pavements can play a major role in transferring of these signs. In some cases a layer of polymer colors spread on asphalt pavement that as time passes and the air warm and vehicle traffic, layer of color is separated. Therefore, using of the pigments that set between the bitumen and asphalt materials can produce colored and durable asphalt with low maintenance costs. In this study, the materials that used in colored asphalt and its specification are introduced and laboratory prototypes of the red asphalt with different percentages of pigments are built and the laboratory results of different samples are compared. At the end, economic analysis of color asphalt used in road pavement is studied.

Microsurfacing successful performance in pavement preservation treatments, increasingly has caused to encourage it. Because of cold mixing and low material consumption compared to other asphalt mixtures, microsurfacing has environmental benefits much more, yet costs less. The mixture also enjoys a good shelf life for high durability. However, due to the very low thickness of the protective layer is not capable of bearing, but can be used as alternative to asphalt overlay for pavements that do not have the structural or load-bearing traffic problems. In this paper, after a brief review of the microsurfacing mixture and presenting technical and functional characteristics, the feasibility of using reclaimed asphalt pavement and crumb rubber in the mixture is perused based on the studies have been done so far. Considering these studies, it was concluded that the use of this recycled materials can improve on the technical characteristics especially mixture viscosity and it can also entail the development of microsurfacing function. Besides, in recent years there has been a trend toward the use of new microsurfacing mixtures containing recycled materials; that of course, more research is needed to examine the laboratory characteristics in accordance with relevant regulations.

The modifying of the rheological properties of pure bitumen to improve the performance of Asphalt mixtures has attracted many researchers in recent decades. The purpose of this study is to investigate the effect of Gilsonit on rheological properties of pure bitumen .For this purpose, different percentages of Gilsonite powder were used to modify the rheological properties of pure bitumen 60/70 .In the study of rheology of bitumen (modified and unmodified), viscosity test, softening point, penetration test and flash point were performed, in addition to, the thermal sensitivity of the bitumen was calculated. The results of this study indicate that the addition of Gilsonite to pure bitumen increases the viscosity and softening point and the penetration index of bitumen decreased. Also, Gilsonite improves the thermal sensitivity of pure bitumen, but this bitumen powder has no effect on the flash point. Gilsonite and bitumen used in this research are from the mine of Ilam province and the Pasargad oil refinery, respectively.

Importance and necessity of concrete, as the most consumed material and the most important construction material has been introduced in the 20th century and also after the water, the material that human consume more than everything is Concrete. While only about two centuries, past after innovation of cement and concrete and also this consuming is growing rapidly. Roller compact concrete use in two different field, the first application field is in dams and the second application is in the Pavements. Today, composites are used in concrete products as a new technology in the construction industry. New materials that have a special place in construction are concrete additives and amplified fiber. In this study, main goal is to look about roller compact concrete for road pavements in terms of different technical parameters and also examine the effect of fiber in it. Because, today, cracking of concrete is considered as one of the most important issues of the day and one of practical solutions is use of fiber. The use of fiber in the roller compact concrete improves compressive strength and tensile strength; and in all the specimens, pulse velocity through concrete decreased with use of more fiber that it is a sign of a better quality of fibered concretes than ordinary concrete. The results of this study showed the importance of application of fiber to improve performance of roller compact concrete for pavements.

Traffic accidents analysis, from the technical and safety points of view, includes its rate and severity. This research focuses on the effectiveness of the traffic parameters like, speed, volume and density on the occurrence of the accidents. Rasht- Roudsar corridor is considered as a black corridor to model the relationship between accidents rate and traffic parameters and the model validity is assured by considering another similar corridor name: Ghaen- Birjand. Using worldwide relationships of traffic parameters to localize traffic accidents rates is the main feature of this study. Using the nonlinear and multi variable regression method to develop the model shows that an exponential function would best fit. Speed- Volume diagram follows an S curve and the result explicit an inverse relationship between accident rate and car speeds with a coefficient equal to 0.25, while there is a direct relation between accidents rate and the traffic volumes with a coefficient of 0.0005.

Increasing urbanization, the urban population and consequently the growth of traffic and movement of urban residential with motor vehicles in out within the city has created many problems in transport system. Accordingly to reducing traffic, transport and air pollution implemented variety programs and plans. One such program that with implementation practical and correct can be considerably peace return with transportation is humanities transport development (walking- cycling). Research type is practical and research method is descriptive- analytical and data collection done the method documentary and survey. Research purpose is evaluation natural and physical of Urmia city with purpose spread cycling. Research results shows that in cycling routes select in additional physical factors affect topography and climate factors. According that cycling routes divided with exclusive, semi exclusive and mixed routes. The only in a limited number for the main streets Urmia city (Beheshti, Mafisaheli, Valfajr, Bahonar…) there is the possibility of created cycling.

Developing countries have encountered with financial problems and crisis in the 1980s that these problems and crisis have reduced the abilities of government in governmental states. This issue made negative effects and impacts to the level of high economic and had bad result both for the private department and state department in countries. The last research about the effects of privatization on operational and financial function and performance, human resource, staff shows that privatization can be good for those companies which are located in countries with average incomes. Analyzing the impacts of privatization on economic is a complicated job and difficult action, but researches have indicated that privatization increase efficiency, productivity, and capital resources. And in this article, the threats that may arise from lack of highways are outlined which could be mitigated by privatization, and the obstacles, as well as the advantages and disadvantages of privatization and its various aspects, are also investigated.