scope:

This Standard applies to mainline and signalled depot sections of the London Underground Railway. 

This standard covers requirements that are applicable for conventional and transmission based technologies except where specifically noted otherwise.

The requirements apply to existing signalling systems used on London Underground. 

The requirements are to be applied to signalling systems that are new to London Underground. 

This Standard focuses on requirements of the Signalling System functionality. The totality of requirements contained within the complete suite of Signalling and Signalling Control Standards, see 5.2.1, must be complied with for these systems.

Purpose 

The purpose of this Standard is to define the Signalling Functional Requirements which are mandatory to the design and modification of all Signalling Systems used anywhere on the London Underground Railway.

Note: The Standard is written in terms which reflect, in some instances, the historical design and implementation existing before the advent of modern signalling systems such as Communication Based Train Control (CBTC). Where specific terms have been used that imply a particular implementation that is not applicable to a new design, then the original term may be read as being equivalent to a new term. For example, 'trainstop' may be the equivalent to an 'Automatic Train Protection (ATP) stop code' used in a new system.