Then for Willesden
And the slightly older numbering plan for Watford.
Then changing to the Midland, Derby
Use of delayed yellow, 'Warning' signals. These two examples show typical uses of the warning condition, this usage was introduced to meet rule 45 without needing to provide a subsidiary signal and is the equivalent of rule 39a applied to multiple aspect signalling.
Derby signal 388 route to 384, allows trains to pull up to 384 without blocking the junction ahead, a full yellow on 388 needs the overlap clear hence blocks the junction. See numbering plan above and this extract from the panel drawing and this extract from the list of routes.
Watford signal 49 route to 44, allows trains into the Branch platform without blocking the Up slow, a full yellow with overlap will require points 324 Reverse and TC177 clear thus blocking the Up slow and would only be used for non-stopping trains. NB The button for 49 is green as this is a slot, the signal being controlled by Watford No.3 box.See numbering plan above and this extract from the panel drawing and this extract from the list of routes.Return to homepage.
Copyright Keith Norgrove.
Last revised: November 23, 2007.