Dutch Railway Research Articles

Collaboration patterns in the Dutch railway sector: Using game concepts to compare different outcomes in a unique development case

Decision-making on changes to large infrastructural systems is complex. It involves many actors, the system shows unpredictable behaviour and the environment in which decision-making takes place is dynamic. In a unique development case of the Dutch railway sector two decision-making processes regarding the same issue are performed in two consecutive years. Although, from a technical perspective, the elements of the processes are similar, the decisions in each year are different. In this paper, we use game concepts to explain the different outcomes. Other frequently adopted decision-based models that focus on the technical perspective do not distinguish between both processes. Game concepts are able to reveal the hidden actor and context dynamics of the process and provide action perspective. To identify the game concepts present in the decision-making process, we first consider whether these concepts are mentioned in interviews with decision-makers in our case. Thereafter, we interpret the processes using the identified game concepts. The fact that, in the second year, more external issues are discussed and pressure increased created room for another decision.

Integration of real-time traffic management and train control for rail networks - Part 1: Optimization problems and solution approaches

We study the integration of real-time traffic management and train control by using mixed-integer nonlinear programming (MINLP) and mixed-integer linear programming (MILP) approaches. Three innovative integrated optimization approaches for real-time traffic management that inherently include train control are developed to deliver both a train dispatching solution (including train routes, orders, departure and arrival times at passing stations) and a train control solution (i.e., train speed trajectories). Train speed is considered variable, and the blocking time of a train on a block section dynamically depends on its real speed. To formulate the integrated problem, we first propose an MINLP problem (PNLP), which is solved by a two-level approach. This MINLP problem is then reformulated by approximating the nonlinear terms with piecewise affine functions, resulting in an MILP problem (PPWA). Moreover, we consider a preprocessing method to generate the possible speed profile options for each train on each block section, one of which is further selected by a proposed MILP problem (PTSPO) with respect to safety, capacity, and speed consistency constraints. This problem is solved by means of a custom-designed two-step approach, in order to speed up the solving procedure. Numerical experiments are conducted using data from the Dutch railway network to comparatively evaluate the effectiveness and efficiency of the three proposed approaches with heterogeneous traffic. According to the experimental results, the MILP approach (PTSPO) yields the best overall performance within the required computation time. The experimental results demonstrate the benefits of the integration, i.e., train delays can be reduced by managing train speed.

Determining the Causes of Train Delays - An Automatic Fuzzy Matching Approach

In order to manage the health of assets, knowledge of conditions on the system level is often required. One of the most common approaches to determine the system conditions is to check the frequency of unplanned or corrective maintenance of considered systems. However unplanned or corrective maintenance usually means the issue has reached an intolerable degree and therefore leaves very limited room to improve the health condition of assets. To depart from the conventional approach of asset health management based on unplanned maintenance, Dutch Railways has decided to focus on operational disturbances, i.e., train delays, due to technical issues of trains in order to determine which system deterioration to investigate at the early stage. This work introduces the framework of the cause determination system for train delays that has been implemented within Dutch Railways. The cause determination is composed of two parts. One is an automatic fuzzy matching system that will match a delay to the most probable service request assigned by the support center. The causes of 40% of delays can be automatically identified by this method with an accuracy of 95%. This significantly reduces the human hours spent in identifying delay causes. The rest of cause determination is manually carried out by the Delay Analysis by Calling project. In this project, the calling team will first call train drivers to ask and record the encountered issues and handling procedures, and then the reliability engineers will determine the causes of delays based on these feedbacks. The calling team therefore serves as a feedback channel for drivers and support center and enables us to analyze on the delay handling and advice given by the support center for continuous improvement and development. Another advantage of integrating a highly accurate and robust fuzzy matching system into an interactive cause identification framework that requires input from various business units is that it intrigues interests and builds up trust in data science technology within the organization. This helps us to smoothly introduce this culture change which often is a critical point in transforming into a data-driven organization, especially for the maintenance industry. Based on the identified delay causes, Dutch Railways has built a Delay Analysis Dashboard which can provide a good overview of system conditions for various fleets, and also provide more possibilities to avoid operational disturbances.

Multi-train trajectory optimization for energy-efficient timetabling

This paper proposes a novel approach for energy-efficient timetabling by adjusting the running time allocation of given timetables using train trajectory optimization. The approach first converts the arrival and departure times to time window constraints in order to relax the given timetable. Then a train trajectory optimization method is developed to find optimal arrival/departure times and optimal energy-efficient speed profiles within the relaxed time windows. The proposed train trajectory optimization method includes two types, a single-train trajectory optimization (STTO), which focuses on optimizing individual train movements within the relaxed arrival and departure time windows, and a multi-train trajectory optimization (MTTO), which computes multi-train trajectories simultaneously with a shared objective of minimizing multi-train energy consumption and an additional target of eliminating conflicts between trains. The STTO and MTTO are re-formulated as a multiple-phase optimal control problem, which has the advantage of accurately incorporating varying gradients, curves and speed limits and different train routes. The multiple-phase optimal control problem is then solved by a pseudospectral method. The proposed approach is applied in case studies to fine-tune two timetables, for a single-track railway corridor and a double-track corridor of the Dutch railway. The results suggest that the proposed approach is able to improve the energy efficiency of a timetable.

Impact of railway disruption predictions and rescheduling on passenger delays

Disruptions such as rolling stock breakdown, signal failures, and accidents are recurrent events during daily railway operation. Such events disrupt the deployment of resources and cause delay to passengers. Obtaining a reliable disruption length estimation can potentially reduce the negative impact caused by the disruption. Different factors such as the location, cause of disruption, traffic density, etc. can determine the disruption length. The uncertainty inherent to the variability of each factor and the unavailability of sufficient data results in a wide distribution of disruption lengths from which a certain value should be selected as the length prediction. The rescheduling measure considered in this research is short-turning the trains that are heading to the disrupted area. To investigate the impact of the disruption length estimates on the rescheduling strategy and the resulting passengers delays, this research presents a framework consisting of three models: a disruption length model, short-turning model and passenger assignment model. The framework is applied to a part of the Dutch railway network. The results show the effects of short (optimistic) and long (pessimistic) estimates on the number of affected passengers, generalized travel time and number of passengers rerouting and transferring.

Macroscopic multiple-station short-turning model in case of complete railway blockages

In case of railway disruptions, traffic controllers are responsible for dealing with disrupted traffic and reduce the negative impact for the rest of the network. In case of a complete blockage when no train can use an entire track, a common practice is to short-turn trains. Trains approaching the blockage cannot proceed according to their original plans and have to short-turn at a station close to the disruption on both sides. This paper presents a Mixed Integer Linear Program that computes the optimal station and times for short-turning the affected train services during the three phases of a disruption. The proposed solution approach takes into account the interaction of the traffic between both sides of the blockage before and after the disruption. The model is applied to a busy corridor of the Dutch railway network. The computation time meets the real-time solution requirement. The case study gives insight into the importance of the disruption period in computing the optimal solution. It is concluded that different optimal short-turning solutions may exist depending on the start time of the disruption and the disruption length. For periodic timetables, the optimal short-turning choices repeat due to the periodicity of the timetable. In addition, it is observed that a minor extension of the disruption length may result in less delay propagation at the cost of more cancellations.

Testing the Generality of a Passenger Disregarded Train Dwell Time Estimation Model at Short Stops: Both Comparison and Theoretical Approaches

Train dwell time estimation is a critical issue in both scheduling and rescheduling phases. In a previous paper, the authors proposed a novel dwell time estimation model at short stops which did not require the passenger data. This model shows promising results when applied to Dutch railway stations. This paper focuses on testing and improving the generality of the model by two steps: first, the model is tested by applying more independent datasets from another city and comparing the estimation accuracy with the previous Dutch case; second, the model’s generality is tested by a theoretical approach through the analysis of individual model parameters, variables, model scenarios, and model structure as well as work conditions. The validation results during peak hours show that the MAPE of the model is 11.4%, which is slightly better than the results for the Dutch railway stations. A more generalized predictor called “dwell time at the associated station” is used to replace the square root term in the original model. The improved model can estimate train dwell time in all the investigated stations during both peak and off-peak periods. We conclude that the proposed train dwell time estimation model is generic in the given condition.

Distributed optimization for real-time railway traffic management

We introduce a distributed optimization method for improving the computational efficiency of real-time traffic management approaches for large-scale railway networks. We first decompose the whole network into a pre-defined number of regions by using an integer linear optimization approach. For each resulting region, a mixed-integer linear programming approach is used to address the traffic management problem, with micro details of the network and incorporated with the train control problem. For handling the interactions among regions, an alternating direction method of multipliers (ADMM) algorithm based solution approach is developed to solve the subproblem of each region through coordination with the other regions in an iterative manner. A priority rule based solution approach is proposed to generate feasible suboptimal solutions, in case of lack of convergence. Numerical experiments are conducted based on the Dutch railway network to show the performance of the proposed solution approaches, in terms of effectiveness and efficiency. We also show the trade-off between solution quality and computational efficiency.

The redesign process of the timetable for the Dutch railway sector: a theoretical approach

The design of a new timetable for a railway system is a complex process. Focusing only on the product and the exchange of information between design phases, does not cover the complexity. Strategic actor behaviour and contextual factors are underexposed by research on theory of designing civil infrastructures. Therefore, we investigate the redesign process of the timetable for the Dutch railways from two perspectives: 1) an engineering perspective; 2) an actor and context perspective. To indicate the successes and failures of the redesign process it is characterised using the PSI framework which includes these two perspectives. Several design phases are distinguished and at the transitions misalignments are identified. The misalignments are compared with empirical data to conclude on a set of improvements. Areas perceived as problematic are knowledge transfer between design phases, decomposition of one design phase into several products, and composition of multiple products into one final design.

The redesign process of the timetable for the Dutch railway sector: a theoretical approach

The design of a new timetable for a railway system is a complex process. Focusing only on the product and the exchange of information between design phases, does not cover the complexity. Strategic ...

Resolving Infeasibilities in Railway Timetabling Instances

One of the key assumptions of timetabling algorithms is that a solution exists that meets the pre-specified constraints, like driving times, transfer constraints and headway constraints. If this assumption is satisfied, in most cases a timetable can be found rapidly. Nowadays, railways are being used more intensively, which leads to a higher utilization of the network. Due to this increased utilisation, capacity conflicts occur, so that no feasible solution to the timetabling models can be found, without making subtle but non-trivial changes to the initial input. Resolving these conflicts is essential for railway companies with high utilization of infrastructure. In this paper, we consider infeasible timetabling instances together with a list of allowed modifications of the constraints. We iteratively identify local conflicts in these instances and resolve them by adapting some of the constraints, until there are no more conflicts. The adaptations of the constraints are changes in the right-hand sides that we try to make as small as possible but that resolve the infeasibility. We empirically show that our method can be improved by enriching the initial minimal conflicts found with more constraints. In order to keep the problems tractable, an iterative procedure is used to find solutions to subproblems corresponding to conflicts in the complete timetabling instance. In a case study on instances from the Dutch railway network, we show that these instances can be made feasible within a few minutes.

BUILDING COLLABORATION? CO-LOCATION AND “DIS-LOCATION” IN A RAILWAY CONTROL POST

ABSTRACT This paper studies the design of co-located spaces and how organizational actors experience such spaces. The literature on co-location is ambiguous about how reduced physical distance increases collaboration. To address this problem, we draw on an ethnographic study of a co-located railway control center, housing the largest Dutch railway organizations under one roof. Although the intention of the co-location was to improve collaboration by bringing different organizations into closer proximity, our findings tell a different story. Railway employees developed several territorial practices (preserving existing boundaries, creating new boundaries, and the situational use of boundaries) through which they resisted the design of the control center, thereby changing the control center from co-located to “dis-located.” We argue that understanding the relationship between co-location and collaboration should not only focus on how such spaces are designed but, rather, account for how spaces where collaboration is demanded are experienced and used by employees.

Developing A Service Improvement System for the National Dutch Railways

Customer satisfaction is essential for public and railway services, because firms in these industries have contracts with governments requiring them to achieve specific customer satisfaction targets. In this paper, we describe a National Dutch Railways project in which we identify the major determinants of customer satisfaction. By combining multiple data sources, we link operational and marketing data to customer satisfaction. Our models show that train punctuality and sufficient seating within a train are important factors in customer satisfaction, as are other service elements, such as the availability of Wi-Fi in a train and the condition of facilities at a station. Drawing on the model results, the National Dutch Railways pursued initiatives to increase customer satisfaction. Among these initiatives is the development of an application that allows passengers to check seating availability, the design of a marketing dashboard reflecting developments in customer satisfaction, and the creation of a tool to identify the most critical determinants of customer satisfaction.

Numerical and experimental study of wheel-rail impact vibration and noise generated at an insulated rail joint

As essential track components for rail connections and signal transmission and control, insulated rail joints (IRJs) have been widely used in traditional and high-speed railways. However, the IRJ is considered as one of the weakest parts of railway track structures due to the significant discontinuities in stiffness and geometry. When a train runs over an IRJ, a wheel-rail impact occurs and it increases with train speed. The impact consequently leads to vibration and noise and accelerates track deterioration in the vicinity of the IRJ. This paper establishes an explicit finite element wheel-IRJ dynamic interaction model to simulate high-frequency impact vibration and noise generated at a typical IRJ in the Dutch railway network, and validates the model against a comprehensive hammer test and a pass-by measurement. Good agreements between the simulation and measurements indicate that the proposed model can effectively reproduce high-frequency impact vibration and noise up to 10 kHz. This paper also connects the dominant frequencies of wheel-IRJ impact vibration and noise with the dynamic behaviour of the target IRJ, which may contribute to the mitigation of impact vibration and noise at IRJs as well as to train-borne detection of deterioration types of IRJs.

Integrated Passenger and Freight Train Planning on Shared-Use Corridors

Our study involves the decision-making problems that railway infrastructure managers face in a rail network with dedicated tracks and shared-use corridors. We will analyze the consolidation strategy for shared-use corridors, where the track serves passenger and freight trains. In the stochastic demand case, we will provide an analytical model for the railway infrastructure manager to compute the expected long-term profit using a consolidation system. We will pinpoint the different characteristics of passenger and freight trains, and analytically derive the optimum track allocation and consolidation time, together with the optimum price, in all such cases, using two different model structures, i.e., the additive and the multiplicative forms. We will extend our model further to consider the due-date requirements and volume incentives for railway operators. Our experiments will use realistic parameter values, based on the Dutch railway system.

A microscopic model for optimal train short-turnings during complete blockages

Currently railway traffic controllers use predefined solutions (contingency plans) to deal with a disruption. These plans are manually designed by expert traffic controllers and are specific to a certain location and timetable. With a slight change in the timetable or infrastructure, these plans might not be feasible and have to be updated. Instead traffic controllers can benefit from algorithms that can quickly compute an optimal solution given a disruption specification. This paper presents a Mixed Integer Linear Programming model to compute a disruption timetable when there is a complete blockage and no train can use part of the track for several hours. The model computes the optimal short-turning stations, routes and platform tracks. In this approach short-turning as a common practice in case of complete blockages is modelled at a microscopic level of operational and infrastructural detail to guarantee feasibility of the solution. To demonstrate the functionality and applicability of the model two case studies are performed on two Dutch railway corridors. In the first case, four experiments are presented to show how different priorities can change the optimal solution including the order of services and the choice of short-turning station. In the second case the performance of the model on a big station is investigated. It is shown that the model can compute the optimal solution in a short time.

Storytelling as a strategy in managing complex systems: using antifragility for handling an uncertain future in reliability

The changes currently being experienced by industry demand more flexibility and more interconnections. More interconnections mean more extended domino effects within a network in case of failure. Using the powerful tool of storytelling, this paper aims to highlight the need for a mind-set change in approaching reliability. Firstly, the paper will briefly explain why professionals need new tools and techniques for facing an uncertain future from a reliability perspective. Secondly, an explanation of the increasing importance for embracing disorder will be given, pinpointing the limitations of a deterministic approach and the benefit of a more antifragile method for reliability. Afterwards, the paper introduces the storytelling technique as a tool for breaking the common mind-set on reliability approaches, using a story based on the Dutch railways for underlining the value of antifragility in preparing for unexpected events. Finally, the paper discusses the findings and reflects on future research that would substantiate the benefits in several industrial sectors.

Reconstruction of the rolling contact fatigue cracks in rails using X-ray computed tomography

Rolling contact fatigue (RCF) defects are associated with complex crack networks at the subsurface. A computed tomographic (CT) scanning technique has been developed to reconstruct the 3D geometry of the RCF cracks in the railhead. Sample rails having squats of different severities were taken from the Dutch railway network. Four specimens of different sizes were prepared and investigated with the CT scanner. The detailed procedures of the CT experiment and post-processing work were described. A sequence of high-quality X-ray images was collected during each scan. These 2D images were combined to construct the 3D visualization of the specimen. Various image processing tools were applied to extract and rebuild the internal crack geometries, thus allowing the crack networks to be differentiated from the bulk steel. For validation, the CT results were compared with metallographic observations of the rail surface for all the defects and the vertical section when needed. Discussions were made regarding the proper size of the rail samples and severity of the squats. According to the results, CT allows for a 3D visualization of RCF defects, providing high-quality data on the geometry of the internal cracks. By choosing the appropriate settings and specimen size, CT could accurately reconstruct the squat cracks at different growth stages. This research shows the potential of the CT technique as an intermediate detection and characterization tool among the methods for detecting macro cracks and those for characterizing micro/nano cracks. Finally, a practical specimen design and a detailed scanning procedure are proposed, based on the CT experiments performed in this research.

Multi-level condition-based maintenance planning for railway infrastructures – A scenario-based chance-constrained approach

This paper develops a multi-level decision making approach for the optimal planning of maintenance operations of railway infrastructures, which are composed of multiple components divided into basic units for maintenance. Scenario-based chance-constrained Model Predictive Control (MPC) is used at the high level to determine an optimal long-term component-wise intervention plan for a railway infrastructure, and the Time Instant Optimization (TIO) approach is applied to transform the MPC optimization problem with both continuous and integer decision variables into a nonlinear continuous optimization problem. The middle-level problem determines the allocation of time slots for the maintenance interventions suggested at the high level to optimize the trade-off between traffic disruption and the setup cost of maintenance slots. Based on the high-level intervention plan, the low-level problem determines the optimal clustering of the basic units to be treated by a maintenance agent, subject to the time limit imposed by the maintenance slots. The proposed approach is applied to the optimal treatment of squats, with real data from the Eindhoven-Weert line in the Dutch railway network.

New Insights into the Short Pitch Corrugation Enigma Based on 3D-FE Coupled Dynamic Vehicle-Track Modeling of Frictional Rolling Contact

A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine the system responses in terms of vibration modes, contact forces and the resulting wear with smooth rail and corrugated rail with progressively increasing amplitude to infer the conditions for consistent corrugation initiation and growth. Wear is assumed to be the damage mechanism, and short pitch corrugation is modeled using wavelengths from field observations of a Dutch railway. The contribution of this paper is a global perspective of the consistency conditions that govern the evolution of short pitch corrugation. The main insights are as follows: (1) the longitudinal vibration modes are probably dominant for short pitch corrugation initiation; (2) during short pitch corrugation evolution, the interaction and consistency between longitudinal and vertical modes should determine the development of short pitch corrugation, and once a certain severity is reached, vertical modes become dominant; and (3) in the case simulated in this paper, corrugation does not grow probably due to not only the different resulting main frequencies of the vertical and longitudinal contact forces, but also the inconsistency between the frequencies of the vertical and longitudinal vibration modes and the resulting wear. It is inferred that in the continuous process of initiation and growth of the corrugation, there should be a consistency between them, and this could be done by the control of certain track parameters.