نشریه مهندسی ترافیک
پیاپی 43 (تابستان 1389)

The optimum operation of a transportation system is obviously independent to the workability of the system. This workability is obtained by continual inspection and maintenance on the proper time. Studying the effective and non- effective parameters on rail degradation process specified that the environmental agents would not effectively affect rail degradation. Preventive operations would require a procedure which could anticipate the faults and manage them on the proper time. This process obviously decreases the costs and supports the workability of the system. Reporting the effective parameters on rail degradation and analyzing them by SPSS is one of the basic phases in reducing faults, managing rail maintenance process and also a way of increasing the system’s workability.

Rear-end collisions is frequent type of traffic accidents, in which human errors is the most dominant factor. Along with the recent technological developments in the field of driving task automation like developing advanced driving assistance systems (ADAS), human role in vehicle controlling is changing from a controller to a supervisor, and for this reason traffic crashes are decreasing gradually. Developing such systems like, AICC, ACC and CAS needs detailed data about human driving behaviors and reactions in different situations. So it is important to define a proper warning strategy that, warns driver when he/she is really at danger and immediate reaction is required. Previously, Time-to-Collision (TTC) has proven to be an effective measure for discriminating critical from normal behavior and so could be used in ADAS as a cue for decision-making in traffic. This paper deals with applyingtwo new safety indicators derived from TTC, named TET and TIT instead of TTC.

:The purpose of this paper is identification and prioritization of main factors of delay in road construction projects in Iran. The causes of delay in road construction projects has been identified and developed by using of lessons learned from projects carried out in the world and library studies in this field. Identified delay factors categorized by the origin of the incidence (employer, contractor, consultant and external factors), then using a field survey by a questionnaire and collected elite experts opinion and while completing primary factors, factors weighted and prioritized. Based on the survey was conducted and analysis of the results of its, the most important causes of delays in road construction projects are country's economic unfavorable conditions, lack of financing and delay in payment, lack of risk identification and lack of attention to risk, unstable political conditions, contract reforms and miss estimation of project time. Finally, based on the fact that ranked factors, executive suggestions are presented in order to reduce these delays.

The implementation of communication and information technologies in public transportation field using APTS, will provide new and advanced services to user of public transportation fleet and reduce considerably the costs of fleet management. In this paper, the history of using these systems in the world is surveyed at the first. Then, the user services and advances systems that have high usage in the field of public transportation are introduced. At the next stage, the logical process of determining ITS systems and procedures in consideration of problems and requirements of bus fleet network are introduced and reviewed. Then, the benefit- cost analysis for implementation of APTS in Tehran bus fleet is accomplished that concluded the benefit- cost ratio of 13.7 and rate of return of 672 % in the first year of funding. At the end of paper, the results and outcome of using APTS in line 927 of Tehran bus fleet that accomplished as a pilot project, is assessed and evaluated.

Driver’s instructing and directing to arrest of traffic conflict is primary object that introduced route signing basis. It also has been caused to conduct of drivers without any speed reduction to join it to the main highway and collectors system specially. Observing of data type, installation location and methods, size, fonts and board scale, travel orientation and destination also affect route signing application. However, location of direction boards is most important in urban studies. In this article, the effective design and location parameters of highway and arterials signing are introduced. Tehran municipality’s 1th zone is discussed as a case study for signing in this research. Exist condition, problems and etc have evaluate for this area. Results show that this research has been improved to identify the perfection and defection of signing issues and categorize them quantity to arrange of eliminates.

The purpose of a train scheduling problem is to determine the arrival and departure times of each train in a station considering the travel time and safety constraints. In this paper, two railroad tracks crossing is to be considered. Two important objectives are as follows: 1) minimizing the total time of train delays at a particular time-limit and 2) decreasing the related cost. The trains have priority appearing in the model, as a weight coefficient. Because of the priority of the train and considering crossing, the complexity of the issue is going to be increased. After defining the problem and related issue in an explanatory way, this paper presents the mathematical model consisting of two objective functions. Finally, to show the validity of this model, an example is solved by the Lingo software using the branch-and-bound method.

Impact with the interior of the vehicle and being ejected are the most common mechanisms of injury in car accidents. Based on reports, the use of seat belts reduces the probability of being killed by 40–50% for drivers and passengers in the front seat and by about 25% for passengers in the rear seats. Also investigations show that seat belts are most effective in frontal impacts and in running-off-the-road accidents where the probability of being ejected is high if seat belts are not used. We aimed in this paper to model and to compare the accidents both in restrained and unrestrained conditions, based on classic kinetics fundamentals. According to developed models, we can show the higher the speed of vehicle before the accident, the greater the applied impact to passengers. Also the more flexible the body of vehicle, the less the impact to passengers is. In the case of unrestrained passengers, the further the distance of passenger head to windshield, the greater the impact is. Of course arbitrarily getting close to windshield when accidents, is not the natural habit of passengers. For this reason to make passengers safe during crashes, they have to wear seat belts. Seat belts should effectively be able to stretch in accidents to a constant amount of force, F. This force should keep constant by the full stop of vehicle in accident. Modeling shows that the distance of front seat to windshield should be long enough, in the case of using seat belts. In fact seat belts should be designed in a manner that the force applied to passengers during the accident, remains constant.