(19-09-2017, 07:45 PM)Alan Beavers Wrote: Yes PJW I realised that when I was practising and got to part 3! It's deceptive, on initial glance I thought I'd be able to answer it decently. I could only think of one thing and that was a sideways-on co-acting signal (Nottingham station). Or maybe an in-cab display but as the question asked for novel, PRACTICAL solutions I couldn't say that.At Penzance there is (I assume still; certainly there was) a miniature LED signal hung underneath the main aspect to enable a view from almost beneath. Not a co-actor as such (it was not proved in the same way) but I think just paralleled off the main aspect feed and called something like a "Close-up viewing repeater" to differentiate; it appeared in IRSE News possibly 10-12 years ago as an "interesting signal" . Perhaps this could count as one of the options and your co-actor at right angles as another.
I suppose another option could be a colour CCTV monitor on a mast some 25m beyond the signal which displayed a live picture of the signal itself so that the driver could be said still to be able to observe it even when too close to it to directly observe.
Of course on the roads it is not unusual for there to be temporary traffic lights to implement some alternate single line working when one carriageway is blocked by roadworks and for the lights to be hard on the obstruction but a "When Red Light Shows STOP HERE" sign somewhat on the approach. It is not something that I believe has ever been done on the railways [having said that I think that the Swiss often do not have separate signals for each platform at a passing loop on a single line but make do with a single signal beyond the convergence and display a different aspect on it to signify from which line a movement is being authorised] and I am sure it would need a specific sign and Rule Book amendments, but potentially at least the signal could be relocated further ahead (whereas the question said not possible, this would have been assuming the signal would have to denote the stopping position and this option would remove that constraint) and the relevant sign placed where it used to be. I suppose that this sign might best take the form of a STOP Board with wording "untli signal XYZ displaying proceed aspect". Perhaps the "signal" itself could be built into a modified form of hollow sleeper with the LED aspects shining out of a raised portion of the sleeper within the height envelope of an AWS, angled say 45 degrees upwards to the driver's cab when stopped at the STOP Board.
In former times there were "standing out" signal indicators, but I think these tended to be indicators on the rear face of the signal so that the driver could lean out from the footplate and look back along the platform; whereas these may have been the solution in days of steam, don't see they'd work when there may not even be as much as an opening cab window which could be leant out from.
I noted that at the recently lengthened platform at Waterloo there are co-actors which are not parallel with the main signal but significantly beyond them; these needed a derogation to standards....
Not sure that any of these ideas are very good, but I technically all would be quite possible; gaining acceptance might in practice not be too easy!
PJW