scope:

This document applies to site investigation scoping, site investigations, design, specifying track renewals and the installation of the track bed.

This document applies to all ballasted track for renewals, enhancements and remodelling schemes.

It does not apply to high speed lines above 125 mph.

Purpose

The document sets out a consistent technical approach to track bed diagnosis, investigation and design to reduce the risk of premature track bed failures and high

frequency of maintenance interventions following track renewals work. This standard is a key control for the risk of loss of geometry (cyclic top/twist fault) beyond safety

limits as illustrated in NR/GN/TRK/8001/0203.