scope:

INTRODUCTION

All Network Rail structures are subject to detailed examinations. The frequency should be determined in relation to the site specific risks.

Examination reports are controlled under the Structural Asset Maintenance Programme (SRAMP), with the aid of the Tunnel Condition Marking Index (TCMI). This standardized system for the assessment of Network Rail structures ensures that defect occurrence extent and severity is identified and recorded in consistent manner. Using the SCMI a structure's condition is assessed on a scale of 0 to 100, where 100 indicates it is perfect condition.

This document is intended as a useful guide to understanding the possible causes, and available solution for the repair of typical defects in tunnels. In addition, it provides guidance on the application of the Network Rail standard tunnel repair details contained in Annexe B