From your perspective, why is it essential today to plan construction works and train traffic, i.e. train paths, not separately but in an integrated manner?
Eric
The current situation is often unsatisfactory because construction works and train paths are not truly coordinated in the capacity planning process. This typically results in conflicting objectives: Either construction is planned very densely, which has less impact on service quality, or the service offering is restricted to give construction works sufficient space. However, it is rare for construction works to be sacrificed in favour of the service offering; Instead, the works take longer, are often inefficient, and lead to higher costs. Neither option is sustainable in the long run. From a capacity management perspective it is clear: Construction planning must flow into capacity considerations as early as possible.
Björn
Exactly. And for that a timetable system is needed which takes construction restrictions into account right from the start—not as an afterthought or disruptive factor, but as an equal planning element, with the aim of continuously aligning train operations and construction. In Viriato, the SMA timetable system, we therefore treat construction works and trains according to the same logic: both require capacity on the shared infrastructure, both can come into conflict with each other, and both must be visible and modifiable together.
Björn, directly to you: What exactly needs to change to reduce conflicts between the goals of service quality and construction requirements, and how does your software support this?
Björn
One thing is clear: Conflicting objectives between the running of trains and construction works cannot be avoided. They must be actively managed, and for that, you need a basis for decision-making. In the context of operating and building, this is not a given, as with a longer planning horizon, less precise information is available, and you work with assumptions and simplifications that must be refined as better information becomes available.
This is where Viriato’s three design principles come into play. First, process stage-appropriate actions: The model allows for different levels of detail and enables lightweight rescheduling that can be gradually refined as more information becomes available.
Second, agile comparison of alternatives: To find the optimum balance between train paths and construction work, you must be able to quickly create different implementation timetable variants and compare their impacts. Viriato supports exactly that, with process stage-appropriate precision and also considering bus replacement services.
Third, the openness of the system in interaction with third-party systems. This is especially important for integrated planning of rail operations and construction, because the master source for track closures is usually part of the railway asset management and construction planning system, i.e. a third-party tool. Consistent integrated planning means that track closures are not only visible in the timetable system but are also editable. Modifications should then be able to flow back into the master system via bidirectional interfaces.
Eric
For these tools to be effective, synchronous planning of timetable and construction schedules are a prerequisite. Train paths and construction work must be handled in the same planning process, with stage-appropriate precision depending on the planning horizon. The key point is the comparison of several variants: How do you allocate available capacity between passenger and freight train paths, and between maintenance, renewals, and the construction of new assets so that a global optimum is achieved and not just a local minimisation of construction costs?
And a second point that I would like to emphasise in this context: Timetables and, in particular, the timetables for construction phases must not be planned “too densely.” Recovery slots – i.e. deliberate planned buffers – as well as reserves in running and stopping times are crucial for being able to react to disruptions. This is how robustness can be improved.
Eric, you mentioned robustness. It’s a key term. How do you define robustness, and how can it be assessed in practice?
Eric
Robustness describes the ability of a timetable to absorb disruptions and return to a stable state. It is thus feature of the timetable’s quality and an essential prerequisite for punctuality in operations. In practice, robustness is often assessed relatively rather than by using fixed thresholds: A construction works-free base timetable and various construction works variants are compared, and those that recover best in the event of a disruption are identified.
Björn
Eric has touched on it: Robustness can only realistically be evaluated comparatively. That’s precisely why the practicality of the analysis itself is central. It must be lightweight and efficiently executable in different planning phases so that the insights can flow directly back into the overall planning. This is made possible by using a mesoscopic conflict model: It is low-maintenance, scales well, and thus enables network-wide analyses to be performed. The Viriato robustness module is also fully integrated into the tool, avoiding costly and cumbersome system breaks.
Our approach is based on principles that are comprehensible from a technical standpoint: the input of delays (either static or via distribution functions that can be determined from operational data), simulation of delay development, and the comparison of variants. Precisely because there are no standardised norms for “robust” timetables, this comparative approach is necessary.
Eric
It should be said that robustness remains difficult to measure unequivocally. The same metrics are evaluated differently depending on the network, traffic density, infrastructure, planning reserves, and operating rules, and there are no standardised metrics or comparable datasets across Europe. That’s exactly why Björn’s point - a lightweight, comparative approach - is currently the only practical way forward.
And is robustness sufficiently considered in the planning process today?
Eric
No, often only very little or too late. In many planning processes, robustness is only evaluated once the structural risks are already built into the timetable—when running and stopping times, headways, or reoccupation times are consistently set at their minimum. At this stage, only limited corrections can still be made. Our approach therefore aims to identify a robust state at an early stage in the compared construction timetable variants and to integrate robustness into the planning process in a manner appropriate to each planning phase. This is done across the entire network and before the actual capacity planning or allocation to take any systemic effects into account.
Björn
This early analysis is only possible if the tools allow for it. Robustness analyses should therefore not be a separate, cumbersome step at the end, but rather an integrated part of ongoing planning. This is the only way to technically implement the principle of “early and appropriate to each stage.”
What does integrated planning mean in concrete terms for infrastructure managers, both technically and organisationally?
Björn
Integrated planning means intentionally breaking down traditional planning silos so that capacity decisions are made early, consistently, and are optimised across the entire system. We see the following three drivers: increasing construction works requirements due to aging networks, higher traffic volumes with limited diversion capacity, and regulatory pressure from the EU Capacity Regulation. Siloed planning creates capacity conflicts at a late stage, when rescheduling is expensive or impossible (because it is too late in the formal process).
Eric
It means a change of perspective. The transport of people and freight, i.e. the service itself, is the true raison d'être of the network. Strategies, investments, and construction programmes should always be based on a clear operational objective, which is expressed in timetables and service concepts. These timetables are the common language between infrastructure managers, railway undertakings, and authorities, but also between asset management and operations.
From an economic point of view, the external costs of construction work are central. Earlier, integrated optimisation of operations and construction can help the infrastructure manager to minimise impacts, bundle related work, and simplify the network upstream. Railway undertakings also benefit, for example, when replacement bus services are considered early in the construction timetable variants.
The new European regulation addresses precisely this issue. What does this mean concretely for processes and tools?
Eric
This topic is of central importance. In medium-term planning, the European legislation approaches capacity problems tactically, addressing also the consequences of temporarily degraded or unavailable infrastructure. The new regulation requires that works affecting the infrastructure, known as TCRs (Temporary Capacity Restrictions), are visible in both the capacity model (Capacity Model) and the capacity supply (Capacity Supply). This places high demands on organisations and processes, especially in the medium-term horizon.
Björn
We are specifically preparing Viriato for this. Starting from the autumn 2026 release, our system will support both import and export of the TCR Message Format, the data standard for the exchange of construction restrictions. This is an important step toward future integration with the RNE Capacity Planning Tool and the implementation of a central element of the new European capacity regulation.
What does this mean for infrastructure managers?
Eric
Many infrastructure managers traditionally have a small department for long-term planning and a very strong annual timetable organisation. There is often a significant organisational and procedural gap between these two areas. Regulation now forces them to systematically develop solutions for this medium-term horizon – for a continuous capacity process – including clear responsibilities, robust construction planning, and integrated decision-making processes. This will require some classical change management processes within the organisation, but it is unavoidable.
Björn
We see considerable potential in this organisational change to noticeably reduce the high workload and time pressure in annual timetable planning.
The targeted development of an efficient medium-term planning capability creates seamless planning across all time horizons. This not only eases the burden on heavily loaded organisational units but is also intended to improve planning quality and reliability, ultimately benefiting all the parties involved.
Our system Viriato is designed for this purpose. This is an important prerequisite to ensure that the described organisational development of medium-term planning can also succeed technically in a seamless manner.
And one final question: Why is SMA particularly well positioned for this integrated approach with its consulting and software?
Björn
The integrated perspective is crucial where construction and timetable intersect, i.e. in medium-term planning. And that is exactly what Viriato is designed for. The daily use of Viriato within SMA and the associated short feedback cycles into our product development drives quality and are an advantage we actively nurture.
Eric
Ultimately, integrated system planning is part of our DNA. In both consulting and software, we do not see capacity, operations, and construction works as separate silos, but as elements of a complete system. This perspective is more important than ever, and its significance will only grow due to regulation, complexity, and limited resources.
At SMA, consulting and software work under one roof, based on the conviction that processes and systems must be considered together. Just as integrated planning of construction and timetables leads to better results, sustainable outcomes also emerge in change projects when processes and software are jointly designed.