JOURNAL OF TRANSPORTATION RESEARCH
Year:2012 | Volume:9 | Issue:1 (30)|Papers Count:7

Train induced vibrations have always been a matter of major concern for railway engineers. In addition to the track high maintenance costs, excessive ground born vibrations may cause annoyance to people who live in the track neighborhood. One potential solution toward minimizing these effects is the use of soil embankments as an efficient method for vibrations reduction.A review of the literature clearly shows that the effects of embankment parameters, namely thickness, stiffness and damping, on track response, have not been explicitly discussed. Because of considerable mass and stiffness of an embankment, the study of track behavior, while it is located on the embankment, is of great importance and necessitates more detailed analyses.This paper investigates the influence of embankment parameters on vibrations induced from train dynamic loads. For this purpose, the widely used finite element program, ABAQUS, has been employed to perform continuum analyses. Train loads have been introduced as the step loads and infinite elements have been used to simulate the infinity of the surrounding environment. The model has been verified with field measurements conducted on a high-speed railway track; the results show that the model is valid.As part of the study, sensitivity analyses have been performed on track parameters namely embankment height, stiffness and damping and on the train parameters including axle load and speed. The results of the numerical modeling and the sensitivity analyses reveal that among the aforementioned parameters, embankment height, train speed and axle load have remarkable effects on the track dynamic response.

Travelling is an important aspect of human life. Although various technologies invented to reduce the travel demand, there is an increasing demand for urban and suburban travels. Obtaining transportation facilities to satisfy this demand is one of the most important roles of transportation decision makers. To establish an appropriate policy to adjust the travel supply and demand, the future demand should be forecasted. Railway is one of the safest, cleanest and cheapest modes of travel. Also emerging technologies make it one of the fastest travel modes. Therefore the rail system has a significant travel share among other modes and forecast of its demand is very important. This paper presents some models to forecast the peak (March & September) and off-peak rail travel demand for Tehran-Mashhad which has the most rail traffic in the Iran railway system. The peak travel demand for Tehran-Mashhad railway usually exceeds the rail capacity and the level of insatiable demand is unknown. Constructing the travel demand forecasting model requires historical data of dependent and independent variables. Prior researches have used the number of passengers travelled between Tehran and Mashhad by the rail system instead of real peak demand because of unavailability of data for travel peak demand as dependent variable of model. Identifying the factors affecting travel peak and off-peak demand, this research presents Multiple Regression (MR), Artificial Neural Network (ANN) and two Time Series models produced to forecast the travel demand for Tehran-Mashhad railway. MR and ANN are able to forecast the rail travel demand with more than 95% accuracy. The models estimation of unsatisfied demand for rail travel in peak periods is about 5.5%.

Different legal systems govern on the basis of carrier responsibility. In the Iranian civil law the theory of fault must be proved is followed, while in the trade law the carrier responsibility is based on the fault theory. At the level of international the thought of codification of uniform regulations on the railway transport action system eventually led to the COTIF 1980 Convention that is under CIM regulations. The said Convention has had various amendments through many years and ultimately led to the approval of the VILNIUS or COTIF 1999 protocol. In this regulation the carrier responsibility is based on the responsibility assumption. Thus once the occurrence of the losses is realized, the responsibility is assumed, and is exempted from the responsibility only in the case that proves that the damages caused from an external accident and inevitable. In the 1999 regulations about the carrier responsibility however, in the case of lost or damage of rail transportation systems and railway equipment the theory of assumption fault is followed and therefore with the proof of innocence and doing conventional actions is exempted from responsibility.

Impairment in attention and concentration is one of the major causes of traffic accidents. Between 20 to 50 percent of accidents involving forms of distraction and inattention is. This is study sought to examine the influence attention skills in safe driving. Thus, was attempted to measure and compare selective attention ،divided attention and attention tolerance in two groups of drivers with and without accident experience.Two groups of drivers, one with 155 members each having more than one culpable driving accident, the other with 145 members with no previous accidents, and both having more than two years of active driving experience., who were entered in this research through matched group method, with using selective and divided attention test, stroop test and continuous performance test, were tested their selective and distributed attention and alertness.There was significant difference between the two groups with and without driving accident in correct response and reaction time to stimulus in congruent and disparate stroop tests and in concentrated and diffused attention tests. There was a meaningful positive relation between age and reaction time in congruent and disparate stroop and in concentrated attention test, but there was a meaningful negative relation between age and the correct response in congruent stroop and in the concentrated and diffused attention test.The cognitive test of attention can make a distinction between the accident prone and competent driver. It is necessary to be considered to loss of cognitive abilities due to aging.But due to limitations of standardized, should be Cautious, in generalizing results of this types of test.

Fatigue is one important factor that affects the structure of military and civil aeroplanes. Hence, their life spans and endangers the flight safety. One of the factors that cause fatigue is the change loading on the plane structure. This is why many researches have been done to determine and calculate these loads, especially those applied during the service life. The loads are of two types, namely inertia and aerodynamic. The magnitude of the inertial loads depends on the vertical and angular accelerations that affect the mass distribution of the plane components. Calculation of these accelerations during different air maneuvers is of utmost importance. In this paper, a method has been presented for the calculation of inertia loads applied on aeroplanes during their services life. For this purpose, a training aircraft was selected as a specimen and its fuselage was divided longitudinally in to 100 parts. Then, mass distribution along the plane body was specified and the mass of every part calculated. Finally, to calculate the local shear inertia loads applied on each part, an equation was defined in terms of the linear and angular accelerations affecting the magnitude of the loads using analytical methods.To find the values of the accelerations used in and this equation, the selected training plane was simulated and the results of simulation were validated using the data found from test flights. The inertial loads applied on the fuselage (during a loop maneuver) were calculated using the parameters found from simulation. Obviously, the calculation process can be generalized to wide-body transportation planes too. Results have revealed that the proposed method for the determination of the distribution of the inertial loads applied on the fuselage (during its service life), with low cost and avoidance from real flights risks, is appropriate.

The growing trend towards urbanization has caused problems that, in some cases, are quite complicated. A major problem, especially in large cities, is the traffic. Considering the effects of traffic on different aspects of people’s lives, and the importance of commutation in urban life, specifying traffic relaxing and control policies and strategies becomes very crucial.Different methods exist to analyze different levels of traffic. Traffic is a complicated problem with a lot of feedback behavior which is a function of different elements. Many experts believe that urban commutation is a dynamic system with many influential elements. Thus, its analysis can be a suitable method to analyze and evaluate the results of traffic policies. The purpose of this article is to analyze the problem of traffic based on the causal dynamic model and to simulate its behavior to propose traffic relaxing and control policies using computer. Here, we have chosen Tehran as our case for study.In this research, traffic has been analyzed, at macro and strategic level, using dynamic modeling in the form of system dynamics analysis. First the important aspects of the problem have been specified. Then, the dynamic assumptions have been presented and the causal model constructed. Next, the behavioral credibility has been verified by the available statistics using inter-variable mathematical functions and simulating the models in the "Venism" environment. Then, certain policies have been presented (for the city of Tehran) and evaluated by software simulation. Finally, the one that can control and reduce Tehran’s traffic most effectively has been presented as the executable policy.

The Open Vehicle Routing Problem (OVRP) is an important generalized version of the Vehicle Routing Problem (VRP) that has received a lot of attention because of its numerous applications in industrial and service problems. Its objective is to minimize the total distance traveled by a fleet of vehicles that start from a depot and deliver goods to customers. It is to be noted that the vehicles do not have to return to the depot after delivery. This paper has proposed an effective Imperialist Competitive Algorithm (ICA) as a new meta-heuristic algorithm for the solution of this problem. The proposed algorithm has been tested on 22 OVRP cases from the literature involving 50 to 480 customers. Computational results have shown that to solve the OVRP, ICA competes satisfactorily with other meta-heuristic algorithms in results, nine best known solutions of the benchmark problem have also been found by the proposed method.