Platform sharing & permissive working

[Peter]

Hi,
Am I right in thinking that permissive working is not an acceptable means of working for anything other than coupling trains?
If so, how do we control platform sharing? Signals mid platform seems the obvious solution but how would one get the required overlap?

Thanks

If you are looking at how permissive platform working has been used rather than what is stated as preferred today, have a look at places like the main London termini (Paddington, Waterloo etc) or at places where services start / terminate / divide en route (Eastleigh, Haywards Heath spring to mind). Bristol Temple Meads is an interesting case study on platform sharing because of the way the route indicator effectively gives the driver the authority (or not) to pass the mid platform "signal" which never changes its indication.

If you can find out about how it has been used, you will appreciate some of the risks that may be present and see why is may not be appropriate for general use, but if the relevant risks can be controlled, perhaps not ruled out totally.