Railway infrastructure

The daily organization of passenger and goods traffic is a great logistical feat, and it requires a functioning infrastructure. Functioning infrastructure means a low degree of susceptibility to breakdowns and a high level of safety, with commercial viability ensured at the same time.

With this target in mind, Fraunhofer Rail works on simulation procedures, analyses, concepts and measuring-devices to support infrastructure operators in planning, development, operation, servicing and maintenance.

Planning and Development#

The infrastructure of railways has now become so complex that it can no longer be described accurately with simple cause-and-effect chains. This is where the scientists at Fraunhofer Rail begin:

  • With the ASTRA traffic and economic management model, they create traffic scenarios which take into account various different political strategies and assumptions involving traffic demand and infrastructure expansion measures. They can derive trends in passenger and goods traffic from the system model, assess the effect of the deployment of new technologies and that of various different price and infrastructure expansion scenarios, and forecast the effects on trade, wages and employment.
  • In traffic simulations, the scientists recreate the traffic conditions in rail networks. By investigating what effect the construction of a passing loop would have, for example, or an increase in train frequency, they can identify bottlenecks and recommend measures for alterations and extensions and for improving the degree to which the capacity of the rail network is exploited.

Greater axle loads and increasing running speeds put more strain on the track. Fraunhofer Rail develops simulation and calculation procedures to assess not only wear and material fatigue on rails and points but also the quality of welding processes. In this way, suitable materials and welding processes can be selected early on, in the infrastructure planning phase.

Operation#

Can regenerative energy sources be tapped for rail traffic too? To answer this question, the experts at Fraunhofer Rail use system models; these take into account not only costs which would be incurred by infrastructure operators, and supply reliability, but also the innovation and risk potential of the alternative energy sources and the environmental consequences of their use.

Tariff systems for the use of rail sections should be neutral in terms of their effect on the competition and commercially viable. Taking these requirements into account, Fraunhofer Rail advises infrastructure operators on the development of tariff systems, which are examined for the effect they will have in terms of cost, yield and sensitivity analysis. If a tariff system is also to be geared to environmental needs, the experts calculate the external costs which will be incurred by environmental damage and damage to health so that they can be passed on to the users who cause that damage via the tariffs.

Sound-absorbing walls are essential for noise protection along railway lines. Fraunhofer Rail researches new materials featuring high durability and many different design options, and micro-perforated components which combine sound-absorbing qualities with transparency – a novelty in noise protection. To combat noise from work sites, by contrast, the researchers tend to go for inflatable noise protection elements made of plastic film and membranes which can be deployed flexibly and installed quickly.

Service and maintenance#

Fraunhofer Rail develops laser measuring devices for test trains which can also measure the contact wires and clearance profile of a given track section accurately at high speed. Largely independent of the weather, and relative to the track, the devices gather the positional data of masts and small objects which obtrude into the clearance zone and carry out non-contact measurements of the position and wear of contact wires.

When a train runs, brakes or accelerates, forces are generated which put a strain on the rails and track bed:

  • Fraunhofer Rail monitors the superstructure with a special measuring-wheel which measures the local contact forces in all directions, and with sensors fitted on the track. The scientists then derive servicing concepts and measures from the data gathered. Measurements also enable them to assess the noise, vibration and harshness (NVH) generated by vertical oscillations when the wheel is in contact with the track, and the operational stability of the construction materials used in the superstructure.
  • In order to be able to set intervals between inspections and track grinding operations which make sense in technical and economic terms, the scientists investigate the contact strain and the interaction of wear and rolling contact fatigue on rails and points. Using numerical simulation and assessing welding processes, they clarify how distortion and internal stress in rails can be reduced and cracking prevented.