Ingo A. Hansen

Conflict Resolution and Train Speed Coordination for Solving Real-Time Timetable Perturbations

During rail operations, unforeseen events may cause timetable perturbations, which ask for the capability of traffic management systems to reschedule trains and to restore the timetable feasibility. Based on an accurate monitoring of train positions and speeds, potential conflicting routes can be predicted in advance and resolved in real time. The adjusted targets (location-time-speed) would be then communicated to the relevant trains by which drivers should be able to anticipate the changed traffic circumstances and adjust the trains speed accordingly. We adopt a detailed alternative graph model for the train dispatching problem. Conflicts between different trains are effectively detected and solved. Adopting the blocking time model, we ascertain whether a safe distance headway between trains is respected, and we also consider speed coordination issues among consecutive trains. An iterative rescheduling procedure provides an acceptable speed profile for each train over the intended time horizon. After a finite number of iterations, the final solution is a conflict-free schedule that respects the signaling and safety constraints. A computational study based on a hourly cyclical timetable of the Schiphol railway network has been carried out. Our automated dispatching system provides better solutions in terms of delay minimization when compared to dispatching rules that can be adopted by a human traffic controller

Optimal multi-class rescheduling of railway traffic

During real-time traffic management, the railway system suffers perturbations. The task of dispatchers is to monitor traffic flow and to compute feasible rescheduling solutions in case of perturbed operations. The main objective of the infrastructure manager is delay minimization, but the dispatchers also need to comply with the objectives of the train operating companies. This paper presents an innovative optimization framework in order to reschedule trains with different classes of priority, that can be computed statically or dynamically in order to include the needs of different stakeholders. An iterative train scheduling procedure is proposed in order to compute feasible train schedules for an ordered set of priority classes, from the highest one to the lowest one. At each step, the procedure focuses on the current priority class, preserving solution quality from the higher priority classes and neglecting lower priority classes in the optimization of train orders and times. The multi-class rescheduling problem is formulated via alternative graphs that are able to model precisely train movements at the microscopic level of block sections and block signals. Each step of the iterative train scheduling procedure is solved to optimality by a state-of-the-art branch and bound algorithm. The results show an interesting gap between single-class and multi-class rescheduling problems in terms of delay minimization. Each priority class is also evaluated in order to assess the performance of the different rescheduling solutions.

Evaluating Disturbance Robustness of Railway Schedules

Railway traffic is operated according to a detailed schedule, specifying for each train its path through the network plus arrival and departure times at its scheduled stops. During daily operations, disturbances perturb the plan and dispatchers take action in order to keep operations feasible and to limit delay propagation. This article presents a thorough assessment of the possible application of an optimization-based framework for the evaluation of different timetables and proactive railway traffic management over a large network, considering stochastic disturbances. Two types of timetables are evaluated in detail: “ regular” and “ shuttle” timetables. The former is the regular plan of operations for normal traffic conditions, while the latter plan is designed to be robust against widespread disturbances, such as adverse weather, track blockage, and other operational failures. A test case is presented on a large Dutch railway network with heavy traffic, for which we compute by microsimulation detailed train movements at the level of block signals and at a precision of seconds. When comparing the timetables, a trade-off is found between the minimization of train delays, due to potential conflicts and due to delayed rolling stock and crew duties, and the minimization of passenger travel time between given origins and destinations.

Effectiveness of dynamic reordering and rerouting of trains in a complicated and densely occupied station area

Abstract Railway traffic experiences disturbances during operations that cause conflicts between train paths or even deadlock situations. Dispatchers need actions to restore feasibility and limit spreading of delays through the network. To help them in such a task, the dispatching support tool ROMA (Railway traffic Optimization by Means of Alternative graphs) has been implemented in a laboratory environment. This paper reports on enhancements to the underlying train dispatching model as well as to the solution algorithms studied in order to tackle the increased complexity of busy stations with multiple conflicting paths and high service frequencies. Advanced train reordering and rerouting techniques are compared with straightforward rules and the current approach in the Netherlands. Extensive computational studies based on accepted statistical distributions of train delays for Utrecht Central Station assess the effectiveness of the ROMA tool in terms of solution quality and computation time.

TNV-PREPARE: ANALYSIS OF DUTCH RAILWAY OPERATIONS BASED ON TRAIN DETECTION DATA

TNV-Prepare is a tool that derives detailed information of event times associated with train services from data records of the Dutch train describer systems: the TNV-systems, where TNV stands for the Dutch abbreviation for train number following. The data records contain signaling and interlocking information of an entire traffic control area. The TNV-Prepare output consists of TNV-tables per train line service and (sub)route. For each individual train, event times (with a precision of a second) along the route are given, including train description steps, section entries and clearances, signals, and point switches. The TNV-tables give excellent analysis opportunities of railway operations that have not been possible before.

Performance indicators for railway timetables

Railway timetables must provide competitive travel times and at the same time be able to withstand delays, perturbations, and variations in operating conditions without losing functionality, to achieve a high service level during operations. The art of designing such a timetable relies on several performance indicators related to individual train paths (running and dwelling), dependencies between train paths (headways, turning, transferring, etc.), and integrated train paths (corridors, networks). These performance indicators include infrastructure occupation, timetable stability, feasibility, robustness, and resilience. The quality of the timetable design process can be evaluated by the manner in which these performance indicators are dealt with. This paper gives an overview of these performance indicators, their importance in the timetable design, and their interrelations, and proposes four timetabling levels that represent how well the timetable performance criteria are taken into account in the timetable design process of a specific railway.

Online train delay recognition and running time prediction

Data mining and analysis of standard track occupation data is used to compute accurate actual train delays at stations. Based on historical train describer records the delays can be automatically classified into initial and consecutive ones through comparison of actual with scheduled blocking times. The distributions of running times and dwell times of each line and direction can be estimated conditional on the amount of original delays, route conflicts and factors such as type of rolling stock, peak hours or even weather conditions. The running times of actual trains until the next downstream stations can be predicted at a high precision by means of a new online model whose parameters have been calibrated and tested in the Dutch railway corridor Rotterdam - The Hague.

PROPAGATION OF TRAIN DELAYS IN STATIONS

Train delays occur on a daily basis, and their propagation is a main source for delays experienced by the Dutch Railways. A statistical analysis shows that the mean train delay increases 15-45 seconds for most train lines at The Hague HS station, the Netherlands. Late arrival delays and corresponding dwell delays can generally be fitted to an exponential distribution and a normal distribution, respectively. In this paper, a stochastic model is presented that forecasts the distribution of late arrival and dwell delays. The model incorporates some main constraints of train operations, and is solved by the Monte Carlo sampling approach. Validation shows that the model predicts the propagation of train delays reasonably well in railway stations.

Improving railway punctuality by automatic piloting

The hinder of approaching trains at railway junctions and in stations due to delayed trains still occupying the route can be minimized by the use of on-board processors that automatically determine the speed and travel time needed until the next main signal that protects the route of a conflicting train. The actual location, speed and distance of the trains to the conflict point are continuously recorded by on-board processors and communicated via GSM-R to other trains in the same area. A decision support system for traffic control identifies in time route conflicts between approaching trains automatically, estimates the remaining travel times and indicates the suitable speed to follow by each of the trains in order to assure seamless merging or crossing. The individual acceleration, braking and speed instructions are transmitted to each train and automatically applied by the on-board processor. The automatic piloting of trains enables maximal use of available track capacity, while guaranteeing minimal train delays.

AUTOMATED SHUNTING OF RAIL CONTAINER WAGONS IN PORTS AND TERMINAL AREAS

The development of intermodal container transport is hampered in part by the cost associated with the shunting of trains in marshalling yards, inland and port railway terminals. Many new technologies have been developed in the past decade, but have still not been applied because of high capital investment costs, lack of sufficient market demand and uncertain rates of return. The key for increasing the competitiveness of intermodal container transport by rail is the operation of heavy haul container trains between port and inland railway terminals more frequently with fast, flexible and automatic transhipment, shunting and coupling of container wagons. The operation of self-driven railcars equipped with automatic centre coupling on terminal tracks, which can also be train-hauled on conventional hinterland railway lines, would enable a reduction of shunting and transhipment time and costs in intermodal container terminals by more than 30%.