scope:

INTRODUCTION 

The purpose of this document is to provide background information, design guidance and typical construction methodologies for the application of an Emergency Temporary Mesh Repair Detail in Tunnels as part of the suite of Network Rail Standard Tunnel Repair Details as specified in the Standard Detail Drawings NR/CIV/SD/580 to NR/CIV/SD/581 (herein referred to as SD Drawings). 

Given the many variations in tunnels and tunnel defects beyond reasonable inclusion, the standard Emergency Temporary Mesh Repair Detail in Tunnels (herein referred to as ETMR Detail) will not cover all possible situations. However the ETMR Detail is widely applicable and variations may be made following the general layout. This document provides guidance on the design philosophy, criteria and assumptions adopted in the production of the ETMR Detail as shown in the SD Drawings. This information is intended to allow future specifiers to undertake their own assessment of the individual circumstances to which the ETMR Detail is to be applied and to adapt the design accordingly. 

This document makes reference to NR/CIV/SD/TUM/520, Technical User Manual for the application of Standard Tunnel Repair which serves as a useful guide in understanding the possible causes, and available solutions for the repair of typical defects in tunnels.