Generation of the transport service offer with application to timetable planning considering constraints due to maintenance work

Line planning is an important step in strategic timetable planning in public transport. In this step the transport offer for the customer is generated by the public transport operator, whereby the resulting costs for the operator should be as deep as possible. Mathematical models for line planning allow to create optimized line plans quickly. Planners can use these models to rate and select different alternatives. This is particularly valuable under the aspect of increasing maintenance and construction tasks of the railway infrastructure. We show, that in this case, it is possible to create functional requirements for automated timetable creation from the result of line planning step. The practical use of the involved models is illustrated by a real application example

Development of a prototype for the automated generation of timetable scenarios specified by the transport service intention

Within the next 5 to 10 years, public transport in Switzerland as well as in other European countries will experience major technological and organisational changes. However, changes will also take place on the customer side, resulting in different mobility behaviour and demand patterns. These changes will lead to additional challenges for transport service providers in private as well as public domains. Time to market will be a key success factor and it is unnecessary to mention that due to these factors the speed and flexibility of business processes in freight as well as in passenger transport industry have to be increased significantly. Within the railway value chain (line planning, timetabling and vehicle scheduling etc.) the coordination of the individual planning steps is a key success factor. SBB as the leading service provider in public transport in Switzerland has recognized this challenge and, together with various partners, initiated the strategic project Smart Rail 4.0. The ZHAW and especially the Institute for Data Analysis and Process Design (IDP) of the School of Engineering wants to be part of this transformation process and to contribute with research and educational activities. The IDP research therefore aims for the transformation of academic and scientific know-how to practical applicability. In a first step this concerns directly the current Smart Rail 4.0 TMS-PAS project activities, that concentrate on timetabling issues. The IDP project team considers the integration of the line planning and the timetabling process as crucial for practical applications. To address this in the current research project, we present an application concept that enables the integration of these two major process steps in the transport service value-chain. Although it turns out from our research, that the technical requirements for the integration of the process can be satisfied, rules and conditions for a closer cooperation of the involved business units, the train operating companies and the infrastructure operating company, have to be improved and to be worked out in more detail. In addition to a detailed application concept with use cases for the timetabling process we propose a methodology for computer aided timetable generation based on the central planning object known as ‘service intention’. The service intention can be used to iteratively develop the timetable relying on a ‘progressive feasibility assessment’, a feature that is requested in practice. Our proposed model is based on the ‘track-choice’ and line rotation extension of the commonly known method for the generation of periodic event schedules ‘PESP’. The extension makes use of the track infrastructure representation which is also used in the line planning and timetabling system Viriato. This system that is widely used by public transport planners and operators. With the help of Viriato, it is rather easy to configure the timetabling problem in sufficient detail. On the other side, the level of detail of the considered data is light enough to algorithmically solve practical timetabling problems of realistic sizes. Taking into consideration the technical and operational constraints given by rolling stock, station and track topology data on one hand, and the commercial requirements defined by a given line concept on the other, the method presented generates periodic timetables including train-track assignments. In the first step, the standardized data structure ‘service intention’ represents the line concept consisting of train paths and frequencies. Due to the utilization of infrastructure-based track capacities, we are also able to assess the feasibility of the line concept given. Additionally, the method allows for handling temporary resource restrictions (e.g. caused by construction sites or operational disturbances). In order to assess the performance of the resulting timetable we present a framework for performance measurement that addresses the customer convenience (in terms of start-to-end travel time) as well as operational stability requirements (in terms of delay sensitivity and critical relations)

Improvement of maintenance timetable stability based on iteratively assigning event flexibility in FPESP

In the operational management of railway networks, an important requirement is the fast adaptation of timetable scenarios, in which operational disruptions or time windows with temporary unavailability of infrastructure, for instance during maintenance time windows, are taken into consideration. In those situations, easy and fast reconfiguration and recalculation of timetable data is of central importance. This local and temporal rescheduling results in shifted departure and arrival times and sometimes even in modified stop patterns at intermediate stations of train runs. In order to generate reliable timetabling results it is a prerequisite that train-track assignments, as well as operational and commercial dependencies are taken into consideration. In order to refer to the right level of detail for modelling track infrastructure and train dynamics in the computer aided planning process we present a generic model that we call Track-Choice FPESP (TCFPESP), as it implements suitable extensions of the established PESP-model. We show, how the service intention (the data structure for timetable specification) together with resource capacity information entered into a standard timetabling tool like Viriato can be utilized in order to configure the TCFPESP model. In addition, we are able to calculate quantitative performance measures for assessing timetable quality aspects. In order to achieve this we present a method for evaluating travel times based on passenger routings and a method for evaluating timetable robustness based on max-plus algebra. This approach supports the planner to generate integrated periodic timetable solutions in iterative development cycles and taking into account intervals for local maintenance work

Maintenance timetable planning based on mesoscopic infrastructure and the transport service intention

Planners of maintenance intervals and operations have a strong need for rapid development and assessment of comprehensive and reliable timetable scenarios, which are able to satisfy the requirements of both, the train operating company and the infrastructure operating company. To address these requirements, in this paper we present a use case that is based on the ‘track-choice and line-rotation’ extension of ‘PESP’, the commonly known model for the generation of periodic event schedules. We call the extended model ‘TCFPESP’. This model takes into account the event flexibility requirement of the ‘service intention’ and makes use of a mesoscopic track infrastructure representation. Both properties support an iterative timetable development process with a ‘progressive feasibility assessment’, a feature that is requested in practice. The ‘service intention’ represents the functional timetable specification. The specification is given by an integrated line concept consisting of a set of lines with data defining their types, frequencies, stop sequence, rotation times and connections. Our proposed model takes functional and operational timetable specifications as input and is applied in an iterative way by changing technical parameters in order to generate a timetable with a feasible capacity allocation. Both, the service intention as well as the mesoscopic infrastructure representation can be configured in the line planning and timetabling system Viriato. This system is widely used by public transport planners and operators. It is therefore possible to configure our timetable model by a standard planning tool. After the description of the methods developed, we provide a practical proof of concept by testing the use case for different maintenance scenarios. Thereby we can show that, based on the service intention planners are able to quickly develop feasible timetable scenarios for maintenance intervals. The use case presented in this paper refers to generating short-term timetable scenarios but can also be used in long-term strategic planning

Periodic timetabling with flexibility based on a mesoscopic topology

Many railway companies operate with periodic schedules. The periodic event scheduling problem (PESP) was investigated by many different authors and was applied to real word instances. It has proven is practicability in different case studies. The Swiss Railway Company (SBB) seeks in the project Smart Rail 4.0 a coordination of the railway value chain (e.g. line planning, timetabling and vehicle scheduling, etc.). In the context of an applied research project together with SBB, we have developed an extension of the PESP model. On one hand the extension is based on using a finer resolution of the track infrastructure, the so-called mesoscopic topology. The mesoscopic topology uses in addition to the operation points and their connections, the concrete number of tracks and the allowed track switches. The mesoscopic topology allows creating timetables with train lines assigned to track paths. On the other hand, we use a known, flexible PESP formulation (FPESP), i.e. we calculate time intervals instead of time points for the arrival resp. departures times at operating points. Both extensions (mesoscopic topology and flexibility) should enhance feasibility of the timetables on the microscopic infrastructure. We will call our model therefore track-choice, flexible PESP model (TCFPESP). A preliminary version of this model was shown last year at the OR 2018 conference in Brussel. In the presentation, we will show the embedding of the model TCFPESP briefly in the overall context of the research project. Then, we discuss the mathematical formulation of TCFPESP as mixed integer linear program in detail and show numerical results of a small case study

Periodic timetabling with ‘Track Choice’-PESP based on given line concepts and mesoscopic infrastructure

We present a track-choice and vehicle scheduling extension of the commonly known method for the generation of periodic event schedules ‘PESP’. The extension makes use of the mesoscopic track infrastructure representation widely used by public transport planners and operators. Taking into consideration the technical and operational constraints given by rolling stock, station and track topology data on the one hand, and the commercial requirements defined by a given line concept on the other, the method presented generates periodic timetables including train-track assignments. Due to the utilization of infrastructure based track capacities, we are also able to assess the feasibility of the line concept given. Additionally, the method allows for handling temporary resource restrictions (e.g. caused by construction sites or operational disturbances) up to a certain degree

Periodic timetabling with ‘Track Choice’-PESP based on given line concepts and mesoscopic infrastructure

We present a track-choice and vehicle scheduling extension of the commonly known method for the generation of periodic event schedules ‘PESP’. The extension makes use of the mesoscopic track infrastructure representation widely used by public transport planners and operators. Taking into consideration the technical and operational constraints given by rolling stock, station and track topology data on the one hand, and the commercial requirements defined by a given line concept on the other, the method presented generates periodic timetables including train-track assignments. Due to the utilization of infrastructure based track capacities, we are also able to assess the feasibility of the line concept given. Additionally, the method allows for handling temporary resource restrictions (e.g. caused by construction sites or operational disturbances) up to a certain degree