UK.gov unveils six areas to pilot full-fat fibre, and London ain't on the list

Re: London not on the list

"I wonder if there might be an option for a third rail in the tunnels? Trains would need adapting to have something to make contact,"

Many designs allow for this, it's not unusual. I expect there are compromises compared to a pure high voltage system though, so you weigh up fixing the tunnels once or constraining trains forever.

Also, as a notable example, the Severn tunnel, built over a century ago and part of the current (half-arsed, but that's another story) Western electrification, did in fact did have sufficient headroom (just, AIUI). Maybe otherwise problems from steam locomotive exhaust?

"possibly running less quickly,"

Third rail means less clearance, means lower voltage, means lower power. That definitely impacts acceleration, but I'm not sure about speed; there may also be mechanical issues with shoe pickup vs pantograph. End result is third rail seems to max out at 100mph or thereabouts.

"and some sort of animal grid/protection to make sure nothing too big gets in and fries themselves,"

Well, animals getting on to the railway is bad regardless of electricity and/or tunnels. Trains often can't stop in the distance the driver can see, and an animal won't get much warning of an approaching train. Admittedly a live one has more chance of getting out of the way, but I don't think being alive greatly increases your chances ;).

Re: London not on the list

@ HPCJohn: Not related to fibre optic lines, but the electrification of Queen Street station in Glasgow involved lowering the FLOOR of the tunnels by a few inches.

Please will a rail enthusiast explain further?

I cannot make any claims to be a "rail enthusiast" but the simple answer is to make space for the overhead 25 kV line and the pantograph.

Or did you mean why lower the floor rather than "raise the roof"? If so then I suggest the following: (a) enlarging the roofspace would have risked a rock fall from above - assuming that it is rock overhead and that the tunnels aren't through softer material with a lining to prevent collapses; (b) enlarging the roofspace would / may have been prejudicial to the integrity of roadways, buildings, or underground services (water mains, sewers, etc) above the tunnel. Lowering the tunnel floor was probably seen as the option with the least likelihood of adverse outcomes. It might also have been less expensive!

Doing either on the TransPennine route would almost certainly require the closure of the route for the duration.

A further thought arises about electrifying the (main) route across the Pennines. The objective always seems to be "faster trains", but there is no clear reason why this can only be accompllished by using electric traction. IIRC the reason for the slowness of services on that route is that the trains stop at intermediate stations, so any significant reduction in journey time can only be achieved by having trains that don't stop at them. It follows from that that either (a) the intermediate stations are closed, with no stopping trains at all, or (b) slow and fast services have to coexist on the same tracks. (b) can only work if there are passing loops available (which there may not be) or if the intermediate stations are big enough to allow fast trains to pass through while the slow / stopping trains are standing at platforms. That may be a possibility somewhere like (say) Huddersfield, but then again it may not.

It all seems to boil down to the fact that the politicians have got it into their heads that faster trains will cure all economic ills, but then as Rich 11 stated right at the start of this thread All politicians create their own alternative reality.

Re: London not on the list

If only somebody had given it a few minutes thought before announcing full electrification in the first place...

Steady on; we are talking about "politicians" here. A "few minutes' thought" takes them beyond their attention span. On top of which there is the ever - present problem of politicians trying to understand engineering / technology matters, and that is a mix that rarely if ever has a satisfactory outcome.