On the West Coast route, between London* and where the Northampton route diverges at Roade, there are 4 tracks. These are paired by use so from East to West you have up slow, down slow, up fast and down fast.
North of Rugby it is paired by direction, so from east to west you have down slow, down fast, up fast and up slow (Except for the short 3 track section south of Nuneation)
Is it railway geography that determines this, or historical accident? Or are there current operating reasons that favour 1 layout of another?
I can see the argument for paired by use for south of Roade as it allows a simple clean diverge for the northampton loop. But it comes at a cost as trains needing to 'weave' from fast to slow lines must cross a track for the opposite direction.
*ignoring the DC lines to Watford
North of Rugby it is paired by direction, so from east to west you have down slow, down fast, up fast and up slow (Except for the short 3 track section south of Nuneation)
Is it railway geography that determines this, or historical accident? Or are there current operating reasons that favour 1 layout of another?
I can see the argument for paired by use for south of Roade as it allows a simple clean diverge for the northampton loop. But it comes at a cost as trains needing to 'weave' from fast to slow lines must cross a track for the opposite direction.
*ignoring the DC lines to Watford