What paths might be available for extra South London semi-fast services?

[Railcar]

In this thread I thought I'd explore what semi-fast paths might be available in the network of South London lines.

For example, prior to Covid, the Epsom to London Bridge service via Sutton and West Croydon has been a great success. It started about the time the Bermondsey diveunder became operational and, being fast from Norwood Junction to London Bridge, it makes an attractive and swift way to the City from the suburbs, particularly from the London Borough of Sutton which has no Underground, no Overground and just two tram stops (which scrape the north-east corner of the borough).

Sutton station has semi-fast services to Victoria via Mitcham Junction, but the level crossing at Mitcham Eastfields is the limiting factor to introducing any further services on that line.

Sutton station also offers trains to Victoria via Norbury but those are all-stations and inevitably slow.

Sutton council is at present running a 'Sustainable Transport Strategy' consultation. It has one of the highest car-usage percentages in London and the Council are anxious to get people to use public transport as well as walking and cycling.

The line between Sutton and West Croydon still has paths available.
Am I correct that the bay platforms at Blackfriars are under-used?
If so, are there paths that would allow a non-stop service from West Croydon to Elephant & Castle and Blackfriars via Herne Hill? I've included E & C to offer interchange to Bakerloo and Northern tubes.
Reversing the service could either be at Cheam (for the cost of a reversing siding) if there are paths available through Sutton station, or Wallington (again for the cost of a reversing siding).

 

[JonathanH]

If so, are there paths that would allow a non-stop service from West Croydon to Elephant & Castle and Blackfriars via Herne Hill?

The problem with Blackfriars is getting a path across the Victoria to Kent main line at Herne Hill. As you will recall from Thameslink services from East Croydon going that way for three years, non-stop to Blackfriars is a crawl.

Fast services are the stuff of flyovers and four track railways. They don't really work on two track railways with flat junctions.

 

[Peregrine 4903]

Eh, I don't think the West Croydon Line has many spare paths available, mainly due to the 4 and half minute slow headway, and ARL at West Croydon plus the flat junctions at Gloucester Road Junction and crossing moves at West Croydon.

And while Blackfriars does have spare capacity, the bigger issue is where to send the trains as Herne Hill and Tulse Hill aren't exactly overflowing with spare capacity.

In terms of extra fast services, London Victoria on the Kent side actually has lots of spare capacity. The problem is that due to the numerous flat junctions in South London, sending the services anywhere is what's difficult.

 

[swt_passenger]

There is supposed to be a 2 tph peak service both ways round the Wimbledon loop between Blackfriars and London Bridge. Once Southeastern are out the way.

These sort of “what if“ proposals really need to consider the existing unfulfilled plans of the franchise consultations and specs, as well as what in today’s timetable...

 

[cle]

Wallington works have been discussed, but I recall these being for the ELL extended (2tph?) from West Croydon, once those go up above 4tph.

I think I just wrote similar elsewhere, but if Wimbledon-Sutton became a Tramlink, even though the route isn't currently a rail alignment takeover, there would be debate about what to do on this line. Would 2tph from Streatham to Wimbledon be worth it? Or might more run via Mitcham?