tynewydd wrote:I guess a more basic question is this - what constitutes wrong road when backing? Is it the direction of travel of the train as if it was going in a forward direction (and backing doesn't count) or is it the backing direction that is against the normal flow? I presume I picked the wrong platform and any backing signal should lead into the Down side implying that it is the backing movement that is against the normal flow?
I would agree with Chris that "backing" is inappropriate where you have those signals. Backing only makes sense if you are going against the flow of an Up or Down line. Single lines are bidirectional by definition and you have chosen that to apply also to both your platforms, so there isn't a "Wrong" direction. In this situation, although Up and Down trains would usually use the platforms indicated, I don't think it is strictly correct to label them Up Line/Down Line. However I think it unlikely that both platforms would have been bi-directional, although it could be necessary for example to allow an express to overtake a slow passenger. If it was only freights needing to be passed, they would almost certainly be put into a refuge siding or loop outside the station, but I suppose you don't have room for that. It was fairly common for crossing stations on single lines to have one platform (usually the one with the station building) signalled bidirectionally to cater for switching the box out.
The current limit on rodding is 350 yards, but recommended no more that 200 yards for facing points. The IRSE recommend reducing the limits if there are sharp curves or lots of cranks etc. Various even shorter limits have applied in the past. Whilst you could use a ground frame to control a remote siding such as the factory, it would not be acceptable to do this with the main points on the running line. If the overall distance is short enough, to control the points mechanically the box should be roughly mid-way between the two ends of the loops. This would still leave you with the problem of controlling the crossing. Gates could be worked by station staff, but that's obviously undesirable.
In more recent times, of course point motors, colour light signals and CCTV crossings allow you to work remotely, but history would have dictated the position of the original structure, and this would have been used on resignalling if suitable. But these would rather go against the grain of what you are trying to achieve.
Consequently my feeling is that you would therefore probably have had two boxes - one where you have it (convenient for the crossing) and another near the far end. It solves the problem of handling tokens. With that arrangement, I think you also overcome concern about the number of signals, although it does introduce the question of which box controls what, what is slotted, and whether you need distants under any of the homes.
Runaway catch points on steep inclines were usual on double lines, to catch the back end of unfitted freights running wrong direction if the brake van's brake was overpowered after couplings had broken. However they were not usual in the facing direction, and of course both directions can be facing on a single lines. If a train ran away down a single line, it would be usual for it to be directed into the loop intended for its own direction, and if still unable to stop it would run through the trailing points at the far end of the loop onto the single line, and it would be accepted that these points would be damaged. The signalman would of course send emergency messages!
It might be seen as preferable to divert a runway into a bay platform, cattle dock etc rather than have it continue to accelerate if the line the other side was also falling or if there was a passenger train in its likely path. The signalman would have to decide the least worst option taking into account all the circumstances, but one place he would try to avoid would be a siding containing an explosives train! On the subject of which incidentally, five days ago it was the 70th anniversary of the Soham explosion.
I think I'd be happier with a disc into the factory, as I suspect you would probably shunt a few vans into it rather than bring a whole train straight in. Your goods arm on the bracket might be justified though, on the basis of sighting or traffic, and I'm not sure about GWR practice.