scope:

This standard specifies the:

a) parameters to promote consistent loose-tube optical fibre cabling infrastructure throughout Network Rail's optical fibre network; and

b) permissible optical loss and configuration of the loose-tube optical fibre network that extends and preserves the network's reliability, availability and maintainability.

This document does not cover parameters or requirements for high-capacity fibre cable systems, which are set out in NR/L2/TEL/31200 and NR/L2/TEL/30179.

The design principles and parameters set out in this standard apply to all designs that grow, change, or repair Network Rail's loose tube optical fibre infrastructure. This includes optical fibre infrastructure supporting Signalling circuits and Electrical Plant applications.

This standard applies to people responsible for designing additions to or modification of Network Rail's loose tube optical fibre infrastructure.

This standard does not apply to intra-building optical fibre infrastructure with no operational traffic.

Purpose

The purpose of this standard is to set out the principles and considerations to be taken into account for additions to, or modifications of, Network Rail's loose-tube optical fibre infrastructure. The objective of this is to maximise its potential capacity and apply a consistent approach that perpetuates improved reliability, availability and maintainability of the network.

Compliance with these requirements optimises the architecture and maximises the performance of Network Rail's optical fibre infrastructure and control the risk of its failure to support railway applications.