Last wheel replacemnent

[oxfordjack1]

Dear All,

In depot, it is last wheel replacement. What procedures or ways to prevent another second train follow and go into the route which is for the first train.

Thank you

[Peter]

Dear All,

In depot, it is last wheel replacement. What procedures or ways to prevent another second train follow and go into the route which is for the first train.

Thank you

Very good question.

I am not aware of any specific rules that are laid down from a signal engineering point of view. All yard and depots would be a set of instructions for the operator or shunter and this would cover the nature and number of moves that are allowed. I recall that there was an operations rule about locos detached from the rear end of a train in a terminal platform not being allowed to move forward until the train in front had moved and the driver had seen the signal return to danger, so I would assume that the depot operational rules cover the same sort of thing.

I'm sorry that this is not much help, but maybe someone with a bit more operations experience will be able to assist.

Peter

[PJW]

Dear All,

In depot, it is last wheel replacement. What procedures or ways to prevent another second train follow and go into the route which is for the first train.

Thank you

Very good question.

I am not aware of any specific rules that are laid down from a signal engineering point of view. All yard and depots would be a set of instructions for the operator or shunter and this would cover the nature and number of moves that are allowed. I recall that there was an operations rule about locos detached from the rear end of a train in a terminal platform not being allowed to move forward until the train in front had moved and the driver had seen the signal return to danger, so I would assume that the depot operational rules cover the same sort of thing.

I'm sorry that this is not much help, but maybe someone with a bit more operations experience will be able to assist.

Peter

I think Peter is correct but not the full story perhaps.
Do remember that for UK mainline most depots only have quite a rudimentary form of signalling and generally only with shunt signals whose aspect means "continue at such a speed that you can stop short of any stationary obstruction". Therefore in most cases there is nothing to prevent a second train gong into a sectiomn already occupied by a first- indeed there is often an operational need for this to be explicitly allowed, for example when one long siding is being used to hold multiple trains within it.

If you are thinking of an automated metro railway then clearly the situation is very different; of course there may not even be signals. Alternatiely it could be that the depot has a form of locally controlled lineside signalling and may feature manual driving, even if on the running kline there is full automation. In any such situation the driver (f exists) would be at the front of the leading vehicle of the train and there would be no need for last wheel replacement at all.

Definitely last wheel replacement does give rise to the hazard that a track failure could hold the signal off too long; this can be an issue where perhaps on a goods line signalled to historic standards without overlaps a signal may still be showing Yellow with a train beyond it and the signal in rear could potentially then show Green, yet there is in reality a train still only just beyond the signal ahead (i.e. in what would otherwise have been the overlap) and special precautions needed to guard against this scenario occuring.
Hence only provide on running signals where there is a clear requirement to do so, ensure that the signal is replaced as soon as possible, even in the event of a rightside track failure.