Real-time railway operations are subject to stochastic disturbances. However, a railway timetable is a deterministic plan. Thus a timetable should be designed in such a way that it can cope with the stochastic disturbances as well as possible. For that purpose, a timetable usually contains time supplements in several process times and buffer times between pairs of consecutive trains. This paper describes a Stochastic Optimization Model that can be used to allocate the time supplements and the buffer times in a given timetable in such a way that the timetable becomes maximally robust against stochastic disturbances. The Stochastic Optimization Model was tested on several instances of NS Reizigers, the main operator of passenger trains in the Netherlands. Moreover, a timetable that was computed by the model was operated in practice in a timetable experiment on the so-called "Zaanlijn". The results show that the average delays of trains can often be reduced significantly by applying relatively small modifications to a given timetable.
Reliability is one of the key factors in transportation, both for passengers and for cargo. This paper examines reliability in public railway systems. Reliability of railway services is a complex matter, since there are many causes for disruptions and at least as many causes for delays to spread around in space and time. One way to increase the reliability is to reduce the propagation of delays due to the interdependencies between trains. In this paper we attempt to decrease these interdependencies by reducing the running time differences per track section, i.e. by creating more homogeneous timetables. Because of the complexity of railway systems, we use network wide simulation for the analysis of the alternative timetables. We report on both theoretical and practical cases. Besides a comparison of different timetables, also general timetabling principles are deduced. 5001-6182 Business AbstractReliability is one of the key factors in transportation, both for passengers and for cargo. This paper examines reliability in public railway systems. Reliability of railway services is a complex matter, since there are many causes for disruptions and at least as many causes for delays to spread around in space and time.One way to increase the reliability is to reduce the propagation of delays due to the interdependencies between trains. In this paper we attempt to decrease these interdependencies by reducing the running time differences per track section, i.e. by creating more homogeneous timetables.Because of the complexity of railway systems, we use network wide simulation for the analysis of the alternative timetables. We report on both theoretical and practical cases. Besides a comparison of different timetables, also general timetabling principles are deduced.
Real-time railway operations are subject to stochastic disturbances. However, a railway timetable is a deterministic plan. Thus a timetable should be designed in such a way that it can absorb the stochastic disturbances as well as possible. To that end, a timetable contains buffer times between trains and supplements in running times and dwell times. This paper first describes a stochastic optimization model that can be used to find an optimal allocation of the running time supplements of a single train on a number of consecutive trips along the same line. The aim of this model is to minimize the average delay of the train. The model is then extended such that it can be used to improve a given cyclic timetable for a number of trains on a common infrastructure. Computational results show that the average delay of the trains can be reduced substantially by applying relatively small modifications to the timetable. In particular, allocating the running time supplements in a different way than what is usual in practice can be useful.
In this paper we give an overview of state-of-the-art Operations Research models and techniques used in passenger railway transportation. For each planning phase (strategic, tactical and operational), we describe the planning problems arising there and discuss some models and algorithms to solve them. We do not only consider classical, well-known topics such as timetabling, rolling stock scheduling and crew scheduling, but we also discuss some recently developed topics such as shunting and reliability of timetables. Finally, we focus on several practical aspects for each of these problems at the largest Dutch railway operator, NS Reizigers.
In this paper we describe the successful application of a sophisticated Operations Research model and the corresponding solution techniques for scheduling the 6,500+ drivers and conductors of the Dutch railway operator NS Reizigers (Netherlands Railways). In 2001 the drivers and conductors were very dissatisfied with the structure of their duties, which led to nation wide strikes. However, the application of the model described in this paper led to the development of an alternative production model ('Sharing Sweet & Sour') that both satisfied the drivers and conductors, and at the same time supported an increment of the punctuality and efficiency of the railway services. The plans produced according to the alternative production model trimmed personnel costs by about $4.8million (or1.2%) per year. Moreover, it was shown that cost reductions of over $7 million per year are also achievable. conductors were very dissatisfied with the structure of their duties, which led to nation wide strikes. However, the application of the model described in this paper led to the development of an alternative production model ('Sharing Sweet&Sour') that both satisfied the drivers and conductors, and at the same time supported an increment of the punctuality and efficiency of the railway services. The plans produced according to the alternative production model trimmed personnel costs by about $4.8 million (or 1.2%) per year. Moreover, it was shown that cost reductions of over $7 million per year are also achievable.
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