Stuart Johnson wrote:Looked at in more general terms, Simonstone is an almost perfect example of what might be described as the classic British double track station layout, with crossover, slip connection to sidings, and trailing outlet at the other end. It has the standard signalling necessary to get Board of Trade approval post-1889, and no more.
There were many examples of this layout all over the country, and examining the differences between the various companies' approach to signalling it has produced lots of discussion over the years. However, this is the textbook version!
One further feature of this layout which Stuart might have mentioned is the total absence of facing points. To clarify the term Slip Connection in case you're not familiar with it:
You can cross a train between Up and Down Lines by pulling 6 lever to reverse the crossover.
If you pull both 6 and 7 levers you can cross between the UP Main and the yard.
But you cannot get directly from the Down Main to the Yard at that end - you would use 10 instead.
Note that in both cases the arriving train would always back into the yard.
You can't pull 7 on its own; the locking will require 6 to be pulled first.
The reason that a single slip is used, rather than a double slip (which would have allowed Down trains to run directly into the yard) is that this would constitute a facing point and the Board of Trade strongly discouraged provision of facing points on running lines wherever they could reasonably be avoided as they had frequently been the site of derailments in the Victorian era.
Whilst it is possible to get from the Down main to the Yard at the Great Harwood end, the train would have to back over the crossover 6 onto the Up Main and then go forward with 6 and 7 levers reversed. This is undesirable since it not only involves more movements and takes longer, it unnecessarily blocks both running lines in the process.