scope:

This module covers the application and release of approach locking together with manual and train operated route release for all forms of interlocking systems. These requirements are applicable to new and to altered signalling installations, wherever reasonably practicable and subject to the test of reasonable opportunity.

Purpose

This module forms part of the Signalling Principles Handbook (SPH: NR/L2/SIG/30009).

This module defines the requirements to:

a) maintain the safety of an approaching train after the withdrawal of an authority to proceed at a signal;

b) automatically cancel and release the route after the train has passed the signal.

This module comprises mandatory sections, statements of best practice (to be followed unless an alternative can be demonstrated to be beneficial to the company and no less safe), and guidance. It satisfies the relevant part of the IRSE Fundamental Requirements for Train Control Systems, see Appendix B.