DEKRA Rail brochure

Wheel-railoptimization

Staying focused with an integrated view
One of the most important interfaces in a rail system is that between the wheel and the rail. Management of infrastructure
and rolling stock seldom takes place within a single department and often not even at the same company. In order toachieve the best wheel-rail contact, knowledge and understanding of both sides is absolutely essential. There are many
issues, such as vehicle, infrastructure and user characteristics, as well interface aspects, which affect the interaction between
wheel and rail. This interplay can only be understood and optimized on the basis of an integrated approach.

Wheel-rail contact is an aspect of the vehicle-track system that is
relatively vulnerable and is often the spot where the consequencesof a non-optimal system occur.

Specialized in wheel-rail contact
DEKRA Rail specializes in wheel-rail interaction. We have extensive know-how of both rail and train. We understand the forces
and movements at play between vehicle and rail better than anyone, and we know how the two influence each other. To support
you in making choices, for example, with respect to a specific material or maintenance procedure to be used, we can determine
what the effect will be on the life cycle, the environment, safety
and maintenance costs. To do this, we do measurements, generate
rail and vehicle models to carry out rail-vehicle dynamics simulations, perform analyses and evaluations.

Wear, passenger comfort, derailment risk, costs ofmaintenance
When a vehicle moves along the track, this results in considerable
forces and tensions in the wheel-rail contact. Ultimately thisleads to wear on both the wheels and the track, and possibly to
fracturing as a result of fatigue or impact. DEKRA Rail is able toidentify these forces and indicate the best way to deal with themand what the cost implications will be. If the forces are too
excessive, this can have an undesirable effect on the handling ofa vehicle, so reducing comfort levels for passengers. Wear can also
occur and, in the worst instance, there may be an increased risk ofderailment. Using measurements and model calculations, DEKRA
Rail is able to determine the stresses at play and the related
remaining useful life. We also provide support in the decisionmaking processes with respect to possible management measures,
replacement or maintenance.
If you change anything in one of the four quadrants in the figure,it will have an effect on the other processes. For example, if an
infrastructure manager installs a lubrication system on a set ofpoints, this will have a possible effect on brake and acceleration
behavior and wear on the wheels of passing trains.

Many technical disciplines are required to achieve
optimization
In investigating wheel-rail issues, DEKRA Rail can call on theexpertise of specialists with different backgrounds. Materials
science, mechanical engineering, tribology and electrical engineering, for instance. We take measurements on-site at clients andin our laboratories. We deploy formulas which allow us to understand and quantify the effects. To this end, DEKRA Rail uses
‘Vampire’ simulation software, which simulates vehicle dynamics
and determines the resulting contact positions, displacements,forces and accelerations. We have test rigs for wheel-rail contact.
The rigs simulate and test wheel-rail contact to scale. DEKRA alsouses Final Element Modeling. Based on the forces and resulting
tensions, this method provides insight into the degradation ofindividual components (such as wheels, axles, bearings andfasteners). For example, the initiation and growth of cracks in anaxle can be predicted from the loads which occur, on the basis ofwhich inspection intervals can be planned.

Example of such an approach
If wheels are subject to rapid wear, we try to establish the cause.
We look for any irregularities in the interaction between wheeland rail, for example, in the pairing of materials and the match inthe profiles of the wheel and the rail. Infrastructure will also betaken into account in this process: What is the rail construction,
the welding process and the type of rail used? Have any changes
been implemented in the system, where exactly does the problem
occur (or not occur)?

DEKRA Rail internationally
DEKRA Rail has amassed extensive international experience
when it comes to wheel-rail contact. We have worked with rollingstock operators and infrastructure managers in the Netherlands,
the UK and Saudi Arabia, and also with metro operators in Paris,
London and Mexico City.

Other services provided by DEKRA Rail
> Railway Certification and Assessment Services> ERTMS services> Remaining useful life assessment> Product Testing> NDT services> Rotating equipment condition monitoring

Contact
DEKRA Rail experts can be contacted via:
Telephone+31 30 3005 100

Postal address

PO Box 8125
3503 RC Utrecht
The Netherlands

Business address Concordiastraat 67
Utrecht
The Netherlands
WebE-mailwww.dekra-rail.com
info.rail@dekra.com