For a DLC on TSW I think you could do a class 158 and 159 From London Waterloo up to Exeter st David’s These are (almost) all the stations on the route: 1 Clapham junction 2 Woking 3 Basingstoke 4 Axminster 5 Salisbury 6 Yeovil central 7 Yeovil junction 8 Exeter central 9 Exeter st David’s Maby for a add on you could make the route longer by making it up to Bristol temple meads
Where's Yeovil Central? There used to be Yeovil Town station but that's long gone. Also I'm not sure how this would work. The western end has very long single track sections and 1 train per hour each way. It's not something I can see working out well.
Based on the current 30 mile odd length of routes, you would only get from Waterloo to shortly after Woking as i have already requested, or Exeter St Davids to around Axminster.
Maybe not as "commercial initial routes", but if you look at Train Simulator there are a lot of branch lines which have been very well done by third parties which are popular, including the Blackpool North line, Several of the Devon and Cornwall Lines etc Personally I would like to see the Cardiff Central to Bridgend via Cardiff Airport branch, including the spur to Barry Island, but then that's where I grew up
There isn't that route in TSx. There are scenarios called that, but it uses the Portsmouth Line only as far as Woking
