I think I have to agree with Ianno. You are being quite obtuse. What Option C does is provide at least 4tph from Bolton, so assuming the Southport services go that way (I believe they will?) then the connections will be solid for the Airport.
Will they? Or will the wait be too long? 15 minutes connection time on what is a relatively short journey is too long, really, and I don't entirely trust it not being something silly like 25 minutes; for people to use these connections you need to look at e.g. the connection for Bletchley at Leighton which is about 5 minutes.
I'd object less if I
knew it would be a proper Takt. We clearly have 2 out of the 3 elements - clockface and simple, self-contained routes - but you need all three.
FWIW, designing for connections does actually in some ways mess up neat patterns. Lets's say you have the Blackpools and Southports go through Bolton and Salford Crescent in a neat pattern every 15 minutes. You can connect between them, but 15 minutes is a long time to be stood around in the cold, and is a considerable penalty on say a Wigan to Manchester journey which is well under an hour. The ideal would be that they meet up on adjacent sides of an island platform at Bolton for both-directions interchange before heading off, but we don't have the infrastructure for that. So the only way to get the connections right would be to have a "parade" going through Salford Crescent 5 minutes apart - the ex-Southport, then the ex-Blackpool, then the ex-Atherton southbound, the opposite way round northbound. To be fair that does give you a neat 5 minute pattern at Salford, but it doesn't make for a neat pattern elsewhere.
(There would be big benefit of rebuilding Salford Crescent to 2 island platforms - that way you could do exactly that - have every service from Vic meet one from Pic and vice versa, and wait there 2-3 minutes to give people chance to pop across both ways before continuing - that's
proper Takt)
The whole point of Option C, like parts of South London etc., is to finally tell people that they'll have to work around the trains for the greater good, and not get a daft hourly service to suit them because they might have to make a leisure journey once or twice a month.
Neither of those is right, though South London suffers less due to rather higher frequencies. What you need to do is provide direct services for the key flows, and then timed, planned and maintained connections for the smaller ones, and where they're equal you alternate them as through and connection. That is the element of Takt that the UK persistently forgets, largely because it requires infrastructure (platforms, mainly) to be built without being able to squeeze through yet another 153 once an hour from Rathole-on-Sea to Gypsum-factory-in-the-High-Peak, or somesuch.
In other words, people hate changing - on trains, on buses, whatever - because we don't provide the quality of connection that is needed to make them even consider it. That is arguably the most important element of
Takt.
What you need is Atherton trains to drop into Salford just in front of the Blackpool services; the Southport ones to run just ahead of the Scotland/Cumbria from Bolton as they probably won't stop at Salford. Easy.
You do - I just posted the same, near enough - but that doesn't give you neat 15 minute patterns everywhere, so I bet it won't happen. (The Scotland and Cumbria are also constrained by WCML paths, so it depends if you can tweak the Southport and Atherton timings or not).
