In response to Jerry's post, I would suggest that both CD and RA are potentially of benefit to all trains (DOO and non DOO). The rule book covers this as it allows platform staff to give the 'Ready To Start' signal to the guard using a CD indicator
At some stations (e.g. Manchester Piccadilly), the aspect is not always visible to the driver (particularly for short trains near the buffer stops) so the RA (although at Manchester the indicators actually display an 'R') is used by drivers to move towards the signal, as PJW states the driver needs a 'ready to start' signal and the signal off.
The rule book contains various methods of dispatching trains and I would encourage anyone interested to observe trains being dispatched from various stations. Just remember what you see actually happening isn't always correct. I have seen platform staff ask guards to look out of the window on the other side of the train to see if the signal is off, before giving the guard the signal to close the doors (OFF indicators have subsequently been provided as this is clearly not correct). I have also seen platform staff dispatch a train from a bay platform using the route indicator being displayed rather than the signal showing an OFF aspect (as route indicator was visible from where platform staff stood but the aspect itself wasn't). I won't name the station, but the dispatch arrangements have now been changed for that platform so the doors are opened on the other side of the train as the bay platform line has platform faces on both sides of the line, unfortunately the platform canopies only cover the side of the train the doors used to be opened on and they don't cover the side of the train the doors are now operated on so passengers now get wet when it is raining - all due to the arrangements for dispatching trains!
Also worth noting this subject is particularly topical this week : http://www.bbc.co.uk/news/uk-england-mer...e-20339630
At some stations (e.g. Manchester Piccadilly), the aspect is not always visible to the driver (particularly for short trains near the buffer stops) so the RA (although at Manchester the indicators actually display an 'R') is used by drivers to move towards the signal, as PJW states the driver needs a 'ready to start' signal and the signal off.
The rule book contains various methods of dispatching trains and I would encourage anyone interested to observe trains being dispatched from various stations. Just remember what you see actually happening isn't always correct. I have seen platform staff ask guards to look out of the window on the other side of the train to see if the signal is off, before giving the guard the signal to close the doors (OFF indicators have subsequently been provided as this is clearly not correct). I have also seen platform staff dispatch a train from a bay platform using the route indicator being displayed rather than the signal showing an OFF aspect (as route indicator was visible from where platform staff stood but the aspect itself wasn't). I won't name the station, but the dispatch arrangements have now been changed for that platform so the doors are opened on the other side of the train as the bay platform line has platform faces on both sides of the line, unfortunately the platform canopies only cover the side of the train the doors used to be opened on and they don't cover the side of the train the doors are now operated on so passengers now get wet when it is raining - all due to the arrangements for dispatching trains!
Also worth noting this subject is particularly topical this week : http://www.bbc.co.uk/news/uk-england-mer...e-20339630