scope:

General 

This Standard applies only when:

a) The signalling has become incapable of operating in accordance with its intended specification (whether through failure, damage, design error, or any other reason); and

b) The signalling can only be returned to a functional state in the immediate short term by means of an „irregular adjustment‟; and

c) The risk involved in implementing and operating the irregular adjustment is tolerable, and is as low as reasonably practicable having regard to the arrangements that will be necessary to implement it, the likely duration for which it will be in use and the likely consequences if the irregular adjustment is not carried out.

This standard does not apply to planned alterations to the signalling system, which shall be carried out in accordance with E7501, Alterations to the Signalling System.

This standard applies to the fixed signalling installation (i.e. it excludes any train carried elements).

This standard applies to all sections of railway where London Underground is the Infrastructure Manager under Railways and other Guided Transport Systems (Safety) Regulations, SI 2006 no. 599, unless a formal concession to operate differently has been granted.

Purpose

The purpose of this Standard is to define the requirements when it becomes necessary to make irregular adjustments to the vital signalling system in order to restore service in the event of failure conditions.