نشریه مهندسی ترافیک
پیاپی 45 (زمستان 1389)

In urban Transportation & traffic studies, bikeway design studies are carried out along with roadway design studies. In case that the goal is to design the bikeway paths for the existing transportation network, it is necessary to study the critical & effective parameters in selecting bikeway routes & to identify the potential routes suitable for biking. Various indices have been introduced to measure the feasible paths for biking. This article will assess the measurement indices of bikeways & analyze & compare the existing methods. The results of the comparative study show that an accurate evaluation needs all of the indices be estimated to understand the individual impacts of effective parameters.

Some problems have been created with the growth of demand that some of them could not be solved with increasing the capacity or development of the road. One of the parameters that must be considered in the road design is enough length between entrance and exit area in the highway. When we could not supply this enough length, the drivers change the lane suddenly and after that we have more congestion in our highways. Some different manuals and criterion are for determining the minimum length that three of them have been survived in this paper. Also we decided to compare the situation of our highways to the result of the other counties manuals. For this purpose a part of Chamran Highway has been considered as a case study. With regard to the result of HCM manual, the weaving length is between 450-600 meter that We determine 450 meter for the minimum length. With regard to the result of Iran manual, the minimum weaving length is 170 meter and in the table of design speed this length is 450 meter. We determine 450 meter for theminimum length.avoids cleaning effect of dominant western winds of Tehran city.

Traffic conflicts are phenomenon which obviously reveal situation of traffic culture of the society and the behaviors of street network's users. Increasing in traffic conflicts not only decrease traffic safety level but also cause negative effects in all aspects of traffic system. Traffic conflict method is a common way for traffic safety assess. Especially it is more effective in developing countries situation which have road users with different behaviors. In this paper, first, it is discussed the importance of traffic safety and the worthy role of traffic conflict method in this respect. In the second part, the especial traffic conflict types are defined respect to Mashhad road user's behaviors. Finally, Traffic conflict prediction models are developed for Mashhad signalized intersections. For this purpose, weve used three types of data consist of traffic volume and speed, geometric design and observed traffic conflict characteristics. Totally, 60 independent variables related to mentioned types were defined and assessed. The SPSS software, Multiple linear regression analysis and enter method were used to establish the relationship between different types of traffic conflicts and the intersection variables. 16 signalized intersection of Mashhad were assessed and 11 types of traffic conflicts were modeled. Study results reveals that the most effective traffic conflict factors are respectively traffic volume, quality of road marking, geometric design and signal phasing.

Road Maintenance activities are one of the most costly activities which need to be defined according to clear timelines based on user needs. In the field of the amount of maintenance costs and allocating them, there are main differences between Iran and other countries. In this regard, the main goal is finding and proposing new alternatives for budget enhancement and improving allocation. The amount and allocation process in Developed countries like USA, Britain, Italy and Japan is considered in this research and in the next step, allocated costs to iran provinces are mentioned too. Finally, Comparing analysis is performed between Iran and other countries and main problems and shortcomings were distinguished.

Accidents are caused by various parameters and their occurrence cannot be solely related to a single factor. Therefore, various safety studies have been done to represent models for the process of accidents occurrence. One of the new methods to analyze multi variable events and decisions is "Rough Set Theory". By using and taking the advantage of this method, it explores data sets, and by defining independent variables (accident conditions), and dependent variable (the result of accident), the process of accident occurrence can be investigated and the patterns for those accidents that have been frequently repeated under similar conditions, can be extracted. Police-reported crash data for the year 2009 from Gilan province are used in this study. By having this information and using rough set theory, the prevailing patterns for those accidents which occurred under same special conditions were defined. As a result, non-native drivers were involved in damage only accidents and native drivers were involved in injury ones. Damage only accidents were between vehicles, and injury accidents were the result of collision between vehicles and motorcycles or pedestrians. Straight routes were presented in most of the strong patterns. Damage only accidents were between vehicles, and injury accidents were the result of collision between vehicles and motorcycles or pedestrians. Thus, by knowing the repeated and strong patterns, more effective solutions can be adopted.

Pedestrian safety in high speed and high traffic volume paths is an important issue in traffic engineering. Construction of Grade separate pedestrian crosswalk is a way of safe passing of pedestrian from such paths. Appropriate locating pedestrian crosswalks have an essential role for improving pedestrian’s safety. In these paper first Effective parameters in determining the optimum location of grade separate pedestrian crosswalks such as vehicle volume, pedestrian volume, vehicle speed, pedestrian waiting time for passing, cross section specifications, distance from nearest crosswalk, pedestrian accident data and land use has been studied. Data layer of identified parameters are defined in ArcGIS software. Analytical Hierarchy Process (AHP) is used in order to combine provided layers of information. Finally optimum location of grade separate pedestrian crosswalk is identified in use of ArcGIS. A sample case study has been carried out from Ghods square to Pole Rumi Street in Shariati Street of Tehran. The final output shows two appropriate optimum locations of grade separate pedestrian crosswalks.

The purpose of this study is to propose an algorithm able to handle various constrains and network information while estimation origin-destination matrix. Due to the ability of the proposed algorithm to incrementally estimate the origin-destination matrix, it is capable of regenerating values close to real volumes of counted links. Furthermore, in order to obtain a unique matrix, some constrains in framework of an optimization problem are considered. These constrains include the confinement of the estimated matrix to the initial one as well as the confinement of the matrix elements to generation and absorption values in each zone in the target year. Finally, the performance of the proposed algorithm is evaluated through testing it on the Sioux Falls transportation network. The results demonstrated that the proposed algorithm is highly potential to estimate the origin-destination matrix in medium to large scale congested networks.