International Journal of Civil Engineering
Volume:8 Issue: 1, Mar2010

The track stiffness experienced by a train will vary along the track. Sometimes the stiffness variation may be very large within a short distance. One example is when an unsupported sleeper is hanging in the rail. Track stiffness is then, locally at that sleeper, very low. At insulated joints the bending stiffness of the rail has a discontinuity implying a discontinuity also of the track stiffness. A third example of an abrupt change of track stiffness is the transition from an embankment to a bridge. At switches both mass and stiffness change rapidly. The variations of track stiffness will induce variations in the wheel/rail contact force. This will intensify track degradation such as increased wear, fatigue, track settlement due to permanent deformation of the ballast and the substructure, and so on. As soon as the track geometry starts to deteriorate, the variations of the wheel/rail interaction forces will increase, and the track deterioration rate increases. In the work reported here the possibility to smooth out track stiffness variations is discussed. It is demonstrated that by modifying the stiffness variations along the track, for example by use of groutingor under-sleeper pads, the variations of the wheel/rail contact force may be considerably reduced.

designed, and implemented in a large-scale, four-span reinforced concrete bridge. Shape memory alloys (SMA),special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning were used in three different piers. The bridge model was subjected to two-horizontal components of simulated earthquake records of the 1994 Northridge earthquake in California. The multiple shake table system at the University of Nevada, Reno was used for testing. Over 300 channels of data were collected. Test results showed the effectiveness of post-tensioning and the innovative materials in reducing damage and permanent displacements. The damage was minimal in plastic hinges with SMA/ECC and those with built in elastomeric pads. Conventional reinforced concrete plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse reinforcement. Analytical studies showed close correlation between the results from the OpenSEES model and the measured data for moderate and strong earthquakes.

The paper discusses the current state of research concerning railway network timetabling and trafficmanagement. Timetable effectiveness is governed by frequency, regularity, accurate running, recovery and layover times, as well as minimal headway, buffer times and waiting times. Analytic (queuing) models and stochastic microsimulation are predominantly used for estimation of waiting times and capacity consumption anlong corridors and in stations, while combinatorial models and stability analysis are suitable for network timetable optimisation. Efficient traffic management can be achieved by real-time monitoring, fusion, analysis and rescheduling of railway traffic in case of disturbances. Real-time simulation, optimisation and impact evaluation of dispatching measures can improve the effectiveness of rescheduling and traffic management. The display of dynamic signal and track occupancy data in driver cabins, as RouteLint developed by ProRail, can support anticipative actions of the driver in order to reduce knock-on delays and increase throughput.

This paper presents a description of the equipment, testing procedure, and methodology to obtain groundmechanical parameters. The p-y curves for laterally loaded piles are developed. Methods for the development of p-y curves from pressure meter and dilatometer (DMT) test are described. P-y curves are used in the analysis to represent lateral soil-pile interaction. The pressure meter offers an almost ideal in-situ modeling tool for determining directly the p-y curves for the design of deep foundations. As the pressure meter can be driven into the soil, the results can be used to model a displacement pile. DMT tests were performed for comparisons with PPMT tests. Correlations were developed between the PPMT and DMT results, indicating a consistency in soil parameters values. Comparisons between PPMT and DMT p-y curves were developed based on the ultimate soil resistance, the slope of the initial portion of the curves, and the shape of the curves. The initial slope shows a good agreement between PPMT and DMT results. The predicted DMT and PPMT ultimate loads are not similar, while the predicted PPMT and DMT deflections within the elastic range are identical

Current practices in railway track analysis and design are reviewed and discussed in this paper. Themechanical behavior of railway track structure comprising of various components has not been fully understood due to the railway track structural complexity. Although there have been some improvements in the accuracy of current track design methods in recent decades, there are still considerable uncertainties concerning the accuracy and reliability of the current methods. This indicates a need for a thorough review and discussion on the current practices in the analysis and design of railway track systems. In this paper, railway design approaches proposed by various standards along with the results of a wide range of technical researches are studied and necessary suggestions are made for the improvement of current practices in the analysis and design of railway tracks.

Railway service terminals are the places of a railway network usually equipped with costly technology based on highly complicated technological procedures demanding a high degree of coordination and control skills. Designof these systems and the organization of their operation should facilitate reaching to the required capacity togetherwith high quality of service processes as well as minimal costs of resources. Due to the complexity of such systems, a simulation model seems to be the only suitable tool for performing investigations under realistic conditions. The paper focuses on the possible utilization of simulation methods to support the design and optimisation of infrastructure,operation, and process control algorithms in railway terminals. The paper also deals with the most important properties and possibilities offered by the simulation tool Villon and comments on the experience gained during its utilization. The tool supports tactical (mid-term) and strategic (long-term) planning usually related to infrastructural or operational proposals which are supposed to guarantee the optimal (or at least effective) behaviour of the modelled terminal

Logit models are one of the most important discrete choice models and they play an important role in describing decision makers’ choices among alternatives. In this paper the Multi-Nominal Logit models has been used in mode choice modeling of Isfahan. Despite the availability of different mathematical computer programs there are not so many programs available for estimating discrete choice models. Most of these programs use optimization methods that may fail to optimize these models properly. Even when they do converge, there is no assurance that they have found the global optimum, and it just might be a good approximation of the global minimum. In this research a heuristic optimization algorithm, simulated annealing (S.A), has been tested for estimating the parameters of a Logit model for a mode choice problem that had 17 parameters for the city of Isfahan and has been compared with the same model calculated using GAUSS that uses common and conventional algorithms. Simulated annealing is and algorithm capable of finding the global optimum and also it’s less likely to fail on difficult functions because it is a very robust algorithm and by writing the computer program in MATLAB the estimation time has been decreased significantly. Inthis paper, this problem has been briefly discussed and a new approach based on the simulated annealing algorithm to solve that is discussed and also a new path for using this technique for estimating Nested Logit models is opened for future research by the authors. For showing the advantages of this method over other methods explained above a case study on the mode choice of Isfahan has been done.

In this paper, the processes which are currently under development in South Korea, concerning railway safety management system are introduced. Railway safety management system in South Korea is briefly presented, making particular attentions to Systems Engineering Management Plan (SEMP). To make huge national R&D projects successful, systematic management process is essential. In this respect, detailed applying SEMP on railway safety management system of South Korea is discussed including Systems Engineering process and Verification and Validation procedures. Furthermore, a computer-aided systems engineering tool (Cradle) is used in order to make the management process more easily controllable.