Will there ever be a conversion of 3rd rail to OLE

[AM9]

That logic was somewhat flawed IMHO, even when the Electric Spine was being announced, because brand new DC traction substations were being built all the way down the route between Basingstoke and Southampton at the same time, as could easily be seen from passing trains. There was an upgrade to Northam Jn DC substation only a few years ago.

The notional date when the route power supplies become unsupportable presumably keeps receding into the distant future.

Of course, equipment costs aren't necessarily the greatest influence on new OLE installation costs. The reason often mentioned here is that clearances under bridges and in tunnels can have far greater cost implications even before the knitting goes up. But conversely, those structures that do give problems for OLE are in general those built before 1900, (sometimes as early as pre 1850) whereas those built from the start of BR days are generally of dimensions that can accommodate OLE.
Whilst railway infrastructure was built for long life, what has changed is that road bridges over railways were built to take a low volume of horse drawn vehicles or early cars and trucks that were far easier of the infrastructure than heavy streams of 2 tonne cars and 44 tonne trucks. Thus many bridges are being replaced as their size and construction are no longer suitable for current road traffic demands. In this way, the railway estate is slowly being brough up to a standard that OLE can at least fit.

 

[Monty]

SWT looked at 110 mph running a number of years ago between Woking and Winchester. The conclusion was that it could be done safely with the 3rd rail system however the issue was signal spacing and the whole route would need to be resignalled to accommodate faster running, even if and when the change over to OLE were to happen you will still need to resignal the route be it physical ones or ETCS.

 

[AM9]

SWT looked at 110 mph running a number of years ago between Woking and Winchester. The conclusion was that it could be done safely with the 3rd rail system however the issue was signal spacing and the whole route would need to be resignalled to accommodate faster running, even if and when the change over to OLE were to happen you will still need to resignal the route be it physical ones or ETCS.

110mph running wouldn't be a worthwhile improvement anyway. It's fine when there are already faster services running to upliftexisting 110mph capable EMUs to gain a few paths, as has happened on the WCML, GWML and now the MML. I can well imagine that modifying the SWT's extensive Desiro fleet a la the LM 350s was seen as a low cost no-brainer, forgetting that the 200 mile route was already signalled and running 125mph services.
To radically improve the SWML, it would need OLE with the through services being built for 125mph from scratch. There's long been calls here for an 'ac version of the class 444s', and there is now one, - the 397, they can run amongst the 390s and soon the 80x bimodes when they appear.
What the SWML as far as Eastleigh has in its favour is a good straight and relatively unbroken alignment that would probably be relatively easy to clear for 125mph.

 

[Irascible]

The irony of course is the Southern did have OLE 110 years ago

AC OLE, too.

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If you're using AC traction motors then DC supply has to be converted to AC anyway, so the only bit you're not fitting to the train is the step-down from 25kV. It's not a case of sticking a few resistors inbetween the shoes & the motors anymore.

 

[AM9]

AC OLE, too.

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If you're using AC traction motors then DC supply has to be converted to AC anyway, so the only bit you're not fitting to the train is the step-down from 25kV. It's not a case of sticking a few resistors inbetween the shoes & the motors anymore.

It's even more than that. With ac traction motors, they are three phase and receive a variable frequency supply, so even where the train is fed with single phase 50Hz ac, it has to be converted, often by rectifying to DC and then inverting to a frequency appropriate to the speed and load on the motor.

 

[A0]

One of the issues is that you would want to convert Weymouth to Basingstoke in one go. However the electrification along that stretch has been renewed at different times so whenever you do it you're going to have some equipment that has life left.

Though I guess some of that equipment with life left in it could be re-purposed to replace other end of life equipment - in the same way rails were recycled downwards from the mainline to sidings.