Have a lil read up as to how we could still serve MK using a junction at EWR, say if we path up for 6tph stoppers flighted between an 18tph core, if the EWR interchange is the first station call, with 3tph clockface leaving here, and 3tph calling northbound, the 3tph calling northbound would arrive in their path, and leave in the path of the service leaving at EWR, meaning a 10min loss of time, but, stopping paths being configured such that one in two paths is taken North of EWR, so for any stops between EWR and BSP, the services would simply all, 'drop back a path' if they stopped.
This of course could also work in a 20tph core with 10tph stoppers pathed in, but you would need to have calling patterns configured so that services could either drop back into an empty path, or drop back into a path vacated by a service that will be stopping next. That would mean a 6min stop alowance.
If you path for a 6min40sec segment and therefore stop alowance, you could quite nicely fit 18tph core and 9tph stoppers in, that would work out (for my timetabling) as if we had three stops, all services calling EWR, 3tph leave at EWR for MKC, 3tph call at each of the stations between EWR and BSP. Or, simply leave 3tph as empty.
Working off say 18tph core, in groups of three, giving 6tph slow paths available, not unreasonable. Have three intermediate stations at:
EWR, Brackley / A43, Kelingworth / A46.
The service pattern would look something like (Off OOC / Heathrow Jcn) Every 20mins
Fast
Fast (Maybe calls BSP)
Fast (Calls at BSP)
Slow to MKC (OOC, EWR, Bletchley, MKC, Onwards?)
Fast
Fast (Maybe calls BSP)
Fast (Calls at BSP)
Slow to BCZ (OOC, EWR, A43, A46, BSP, BCZ)
The slows would loose 10min per slow stop with an 18/6 profile, if you run with an 18/9 profile and spare 'slow' paths that could be used for slightly slower stock, or as spare paths, still pathed in and out of the station loops. then you'd loose 6min40 per stop.
But I would still provide the running at 3tph Slow Birmingham, 3tph MKC, 18tph Fast, 3tph spare. Since the spares can then be used for ECS or additionals, but would run in and out of the loops and be overtaken by two fasts.
If you're working the 18/9 profile it would be a case of:
Fast
Fast BSP
Slow (MKC)
Fast
Fast BSP
Slow (BCZ)
Fast
Fast BSP
Spare Path
Every 20mins. Yes, departures would need to be timed to the 20sec accuracy...!
If you cut back to 15tph core, or even 12tph core fasts, flighting fasts in pairs, it's easy to path as 10min waits, 16/8tph pushes a 7.5min pathing alowance, and means 4tph 'slow' onto each route.
10tph West and 6tph East isn't an unreasonable pair of numbers, 3tph Brum (Would be 8tph including 'slows' if all where included), 7tph Rugley (Splitting services at CRE, allows good service provision to all routes), 6tph East could include 2tph to Nottingham and Derby CC (Splitting at Trent Jcn), 2tph Leeds and 2tph Doncaster and Beyond. Any additionals can be picked up from the 4tph 'slow' pathed services, that don't all need to actually run fully slow, 2tph could call at EWR only and the other 2tph 'all shacks' the fallback pathing allows this. 18tph core is more desireable as it would allow heathrow and international services to kick about... But anyway, I can discuss this pathing thing till I'm blue in the face.
Can anyone else see value in opening a branch off as part of EWR to Bletchley and Milton Keynes Central, and sending say, 3tph that way, and call another 3tph at the EWR station. (So we can use the 18/6 or 12/6 pathing strategies, allowing 21 or 15tph up to BSP) 18/6 would mean falling back by 10mins, or 18/9 is proberbly the limit and would mean a 6:40 fallback.
PS: 18/6 would provide a clockface 6tph from EWR, 3tph from MKC, and 3tph to any other intermediate stations (at the cost of 10mins journey time each) and if the extended slows continued to BCZ, provide their links to BSP, fasts also calling BSP for convenience, and provide enough paths to keep everyone N of BSP happy for a long time (15tph, 8L 7R?)