Hmmm glad ChrisB’s post has resurrected this thread as your above comment Graham makes me wonder why one of the two limited stop Bristol-London can’t go via Bath rather than both going via Parkway when the hourly XC▸ service went this way and stopping at Bath.
Could it be that the new timetable includes a path or allowance from Bristol to Bath Spa for an additional (Metro West) stopper?
Express leaves Temple Meads at :00
Stopper leaves at :03.5, Stopper reaches Bath Spa :20.5 (17 minutes), Stopper leaves Bath Spa :22.5
Express leaves Temple Meads at :15, Arrives Bath Spa :26
As planned, you have 3 expresses most hours (2 x
PAD» , 1 x PMH); stepping them up to 4 consistently and evenly (3 to London) would leave no slack / recovery - above shows how a local between two departure from Temple Meads with a 3.5 minute headway is at the very limit. All it needs is a platform delay ...
Stoppers go up to 2 an hour "Metro West" and you can see the problem of putting in a Saltford stop. You can also see the lack of time to reverse at Bath Spa, and note that doing so would reflect would reflect delays in one direction into the paths in the other. And there's the
SWR» trains to add in there too.
It is of course much more complex that this - with only 2 of the four 'intermediate' paths at :04 :19 :34 and :49 actually being tight stoppers (that helps) and flat junctions at Bristol East and Bathampton to path (that hinders).
