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Project number: 2021-STN-020

Assessing compatibility between rail vehicles and underline bridges


The project developed guidance about the dynamic risks to underline bridges where rail vehicles operate at over 100mph. It also included improvements to relevant standards, a webpage, and an online route availability calculator.
'The project team have produced a valuable package of resources to help industry in this specialist area.'
Ben Wilkinson
Network Technical Head for Structures, Network Rail

The challenge

The limits of validity of the route availability (RA) system are set out in GERT8006 Route Availability Number for Assessment of Compatibility between Rail Vehicles and Underline Bridges. Outside these limits, a Stage 3 compatibility check is required as well as Stage 1 and 2 checks. Previously there was no guidance on how to carry out the Stage 3 check. Network Rail submitted a Request for Help in July 2021 for the development of a Guidance Note about this.

The Guidance Note needed to show how to evaluate the risk of excessive dynamic effects in underline bridges for new rail vehicles. It also needed to cover modifications to existing bridges and the installation of new ones.

The Rolling Stock Standards Committee also asked for an online tool for deriving the RA number for rail vehicles.

What we did

In June 2024, we published a new document GEGN8616 issue one Guidance on Evaluating Excessive Dynamic Effects in Underline Bridges. It gives guidance on how the Stage 3 dynamics check can be carried out.

The Guidance Note is a result of jointly working with Network Rail. It was based on previous research and best practice from the GB rail industry. A webpage on route availability was also created. This includes all the relevant standards and the Guidance Note in one page.

We also published a calculator for deriving the RA number for rail vehicles for members to use.

Benefits delivered

The contribution of these standards changes in realising value to industry opportunity was categorised as important/essential.

The value of industry opportunity was estimated to be £72,000 over a five-year period.