scope:

All problems related to hardware and its generic application software currently in use in SSI installations on Network Rail, discovered during investigation by specialist equipment investigation organisations.

This document incorporates brief details of identified problems and provides the following for each situation:

• When the identified problem arose

• What the problem was/is

• What actions were taken to overcome the problem in terms of modifications/or specification changes

• Relevant references

Where further or more detailed information is required, reference should be made to TI Reports and other identified reference material.

NOTE For the purposes of this document, all failures have been reduced to their root cause and categorised as such. The root cause often has little to do with the technical investigation report title, as this is invariably based on the location and end effect of the problem in question.

Guidance on whether any solutions should be applied retrospectively is outside the scope of this document.

Purpose

This Guidance Note summarises significant SSI hardware problems that have been identified on Network Rail infrastructure as a result of technical investigation, and the resultant changes made. It supersedes RT/E/C/17903 Issue 3. This information will be useful to those wishing to fully understand the reasoning behind a particular change to SSI equipment or its application.