What is the quickest diesel passenger services under the wires could end?

[Trainbike46]

In a hypothetical situation where, after the next election, the government decides that diesel passenger trains over electrified lines should end ASAP - how long would it take?

Clearly this would require (many) more bimodes, as well as strengthening of power supplies in certain places. Potentially in some places extending the wires may also be considered.

What are the likely constraints that would crop up?

 

[Snow1964]

About 10 years for about 95% of diesel on electrified tracks.
Simply because many of the diesels are 30+ years old.

There are bits where some routes that run along electrified track for short distances, but are basically diesel. eg Carmarthen-Cardiff.
These are unlikely to change for decades

 

[cslusarc]

I think that splitting some existing services in two (or more segments) could make sense especially if that service reverses enroute.

 

[stevieinselby]

What fraction of the UK diesel passenger rolling stock fleet never operates on an electrified line?

I'm fairly certain it will not be a particularly large fraction.
At which point is it worth keeping a fleet of pure diesels? SNCF has come to the conclusion that it is not.

There is a difference between fleet and diagrams. An operator may have a number of daily diagrams that don't come within sight of electrification, but with trains deployed on different routes each day there may not be (m)any specific units that don't ever encounter electrification as they work on a variety of routes. That is pretty irrelevant if they could be ringfenced for particular services without any great loss of flexibility.

On that basis, (and not counting branches that join an electrified mainline for a few hundred yards)...
GWR - all Devon and Cornwall branches, Cornish main line locals, Bristol locals, Thames Valley branches (including Oxford)
Chiltern - ALL
Wales - Swanline, Heart of Wales, Conwy Valley, Borderlands
West Mids - Snow Hill lines, Kenilworth line
East Mids - Matlock, Skegness, Robin Hood, Lincoln (PBO–DON), Barton
Northern - Hadrians Wall, Durham Coast, Esk Valley, Tees Valley, Yorkshire Coast, Colne, Ormskirk, Rose Hill, Hope Valley, Harrogate, Pontefract, Barnsley, Brighouse, Penistone, Nottingham, Lincoln, Scunthorpe
Anglia - Sudbury, Felixstowe, East Suffolk, Bitterne, Wherry
Scotrail - Girvan/Stranraer, Tweedbank, Kyle, Far North, Aberdeen locals/Inverness

There are plenty of those routes that could and should be at least partially electrified, but for the foreseeable future there will be ample work to keep the current diesel fleet employed on unelectrified lines for most if not all of their working life.

(moved from thread on "Chiltern tender for 20 - 70 units")

 

[Jan Mayen]

If we are allowed to include diesels over the third rail, you could restrict the Marshlink services to operate Hastings to Ashford only. Likewise, Uckfield could only be served from Oxted. I'm not suggesting these should be cut back to reduce diesel over third rail, but could be (excluding running to/from Selhurst depot, of course).
An even less likely candidate is to terminate the Cardiff - Portsmouth at Southampton, and the Exeter - Waterloo at Basingstoke.
Mind you, given the shortage of rolling stock they would then be able to lengthen services if they did!

 

[HSTEd]

The simplest answer is, however long it takes to order ~3000 rail vehicles to replace all the diesels with electrodiesels and electrodiesel-battery vehicles.