NR NB 204/APP1 ISSUE 2 PDF

See NB204/Index. This appendix should be applied when:

• new signals are to be provided;

• existing signals are to be re-controlled;

• existing control systems are to be renewed or re-platformed.

NOTE: Alterations to existing installations should follow this appendixwhere reasonably practicable, unless doing so

would create a significant risk of signaller error, in which case the existing practice in that location should be retained.

Reason for issue

When stopping and cautioning trains at an automatic signal with a signal replacement facility, the

signaller could omit to re-operate the signal replacement control (and apply a reminder again) after a

train has been cautioned. This could result in the signal clearing for a following train before the

signaller has cautioned its driver. With larger control areas the likelihood of this occurring increases.

This notice board is being issued in advance of a planned change to standards to require any

automatic signal which can be controlled to red by a signaller to require specific action on each

occasion that it is required to show a proceed aspect, unless the signaller has set the signal to work

automatically. These signals will be known as Controlled (Intermediate) Signals and will be provided

in lieu of automatic signals with a signal replacement facility from the signal box.