Going to nitpick here but quite a lot wrong with this post.
On this point - there is already plenty of unused capacity already available on the Basingstoke to Reading services with XC hourly (I believe, may be more) and GWR half hourly. They could put doubled up 165s but they have even downgraded this to a 150 service as of late. Is there a draw beyond Reading? Maybe so but even with Western access this is one change at Reading rather than up to Hayes and back down.
I don’t think they would want to run via Reading services as Basingstoke has limited links. It’s either back up towards Woking, down to Salisbury (most towns have much better access with GWR stations back to Reading and faster) or down the long long winding road via Winchester.
That’s a complete not sequitur. Why would this free up paths?
Again I’m lost. Another non sequitur. Surely this would
add another two paths an hour if on a 2tph timetable? And if hypothetically you ran the Southern access as effectively a Basingstoke stopper that then turned into a Waterloo via Virginia Water service then who would you fill the train with? It’s a slower service via Chertsey especially when commuters would simply get off at Byfleet and NH or Egham to change?
Adding frequencies for everyone to simply leave halfway through at the same two predictable bottlenecks would be stupid and a waste of timings on the network.
The SWML is already chockablock and is built and run in a way where there are more Jesus Nut failure points than I care to count. The services (if built because that means removal of more than ten level crossings, some that will be considerably challenging technically) would probably be a simple stopping pattern as below.
- Paddington - Heathrow - Slough - Reading
- Paddington - Heathrow - Staines High Street - Woking - Guildford
Anything more is pure crayonista.
By linking Basingstoke/Reading with Reading/Heathrow/Paddington (Western Approach) it removes changes and those changes that you do have can be done at Basingstoke rather than Reading. This has the advantage that someone unfamiliar with the railways only had 5 platforms to pick from with what appears to be better staff visibility.
You so have to bear in mind that we are probably talking about at least 5 years away as probably realistically planning for10 years and so what is currently served by a 3 coach unit may need more than 4 coaches (it certainly does now in the peaks).
XC services help with keeping some people off the local services, however they may not help with getting to Heathrow depending on timings.
I've not brought such an idea from no where:
https://www.railmagazine.com/news/2015/09/24/network-rail-predicts-new-route-requirements
Destination boards at London Paddington could be displaying services for Southampton via Heathrow Airport in future years, Network Rail suggests in one of it latest route studies.
There's quite a lot of people who travel through Basingstoke at present, as there's services (ignoring Salisbury and West as you point out that they would probably go via the GWML anyway, but they may not; as someone from Honiton may be just as quick to go to Basingstoke and change than change at Salisbury and then change again to get to Reading to change for a third time) to Andover, Winchester, Portsmouth, Southampton, Bournemouth, Poole and Weymouth. That's a lot of people that could benefit from travel to Heathrow who currently all would most likely drive at it would be quicker than using public transport, after the Western Approach is built public transport should start to be much more of an option.
That's before you consider the large numbers of businesses that there's in Basingstoke.
Given the capacity issues that there currently are between Basingstoke and Reading a good first step would, in my mind, to be to replace the local services and then when capacity improves happen look to bring in the faster/longer distance services looked to above.
The Southern Approach is quoted as providing 2tph to Guildford and Basingstoke (so again not me with my crayons). As such the will be extra services between Woking and Guildford, the paths are probably due to the fact that Woking's junction would also need to be grade separated (again a project often quoted in NR documents) and from the fact that the capacity constraints on the SWML are more to do with all the services that join it rather than on the 4 tracks through Woking.
There's also been discussions about Guildford gaining an extra station, so to serve that without showing down the Portsmouth services it could be served by the Heathrow services.
The suggestion for the Southern Approach services was to add them between Woking and Basingstoke as stoppers. Yes this would mean 4tph for the likes of Hook and Winchfield, which although could do with a more frequent service wouldn't justify that level. The reason for this would be because Basingstoke would have services via the Western Approach route to Heathrow (which I'm lead to believe should be quicker) and so there's unlikely to be many that would wish to use the Southern Approach services to go to Heathrow and so you're more likely to generate more passengers by running it as a stopping service than trying to run it fast or semi fast.
As 4tph wood be too much I was proposing moving one of the existing services to/from London to serve Farnham, with it then forming a second service an hour between the and Guildford. Those from Farnborough have fast services and so the to use those to get to Waterloo, the other stations could either use the other Waterloo service(s) or could change at Farnborough or Woking to carry onto Waterloo with little or no time penalty. With 1 direct service to Waterloo and then two other services which would get you the equally quickly as the direct service most people would see that as an improvement over the existing 2tph, especially as you'd also gain a more frequent service westbound AND services to Heathrow.
All I've done is suggest calling patterns for services which have been suggested by others, including those well known crayonists NR, in a way that could bring larger benefits than just running the services fast.