NR TI 168 ISSUE 1 PDF

This instruction applies to all Signal Sighting undertaken on Network Rail managed infrastructure. This applies to both assessments of existing signals as part of line speed increases, SPAD investigations and also in connection with Infrastructure change.

Purpose

As part of the Signal Sighting process, the Signal Sighting Committee (SSC) needs to establish how long it will take a driver to identify, read and interpret a signal's display in different circumstances.

The Minimum Reading Time (MRT) is agreed by the SSC based on a number of factors. When completing the MRT consideration must first be given to removing the risk; rather than increasing the MRT. Where increasing the MRT is appropriate this instruction provides guidance and information to promote consistency in the allowances added to the base time of 8 seconds.