Edwin_m

From places served by HS2, I'd say it would be the preferred route to get to Heathrow. As well as the journey time saving to Old Oak, there will be one relatively simple change of train there instead of the schlep from Euston to Paddington or the Piccadilly.

And presumably then they then sit for a couple of years doing nothing, in a confined and possibly damp environment. And are expected to work perfectly thereafter, without any possibility of pulling them out for maintenance.

I saw a TV programme recently (probably a repeat from some years ago where they interviewed a geologist who was called out to one such leak. She tasted it and was able to reassure the workforce that it was a fresh water spring and not an inundation of the sea.

Gizmo has at least eight when we're trying to get him into a cat box.

A more recent example is between Kings Norton and Longbridge, where only the outer two tracks are electrified (25kV in this case). Continuing on towards Barnt Green only the inner two are electrified.

Most tram-trains can pick up either their main line voltage (15kV or 25kV) or 750V from the same pantograph, including the Sheffield ones although those only every use 750V. Changeover is via a longer than usual neutral section which causes both sets of traction equipment to be disconnected until a voltage sensor works out what the new voltage is and connects the appropriate one. I believe this is similar to the old 6.25kV to 25kV changeovers in places like Glasgow, and also carried some risk of a large bang if something goes wrong!

Some similarities to this derailment, probably caused by technicians doing the wrong thing, though inside the equipment room in this case. The chain of events is consistent with someone working on the circuits and managing to reverse the points after the train put the signal signal back to red but before it reached them. Depending on circuit design and the exact error made, the route lights could be wrong and the point out of correspondence on the panel, but the former could be explained if the signaller put the route back as soon as the train passed, and the latter if whatever fault was cleared before anyone noticed. https://www.railwaysarchive.co.uk/docsummary.php?docID=529

It was an interesting and unique bit of railway, but these days all there is to see is a junction underneath a 1960s flyover, so it probably doesn't make very good television.

The gap only needs to be one coach long. Main line units have a bus cable linking the shoes within the unit, but tube stock only links the shoes on an individual car.

For long freight trains in North America, a brake release and recharge can take several minutes. This is why separate locomotive brakes (generally dynamic, regenerating via the traction motors and dissipating heat in resistors) are so important for keeping the train under control when descending long gradients.

Thanks for clarification - I vaguely remember it now. However, all it needed to unlock the land was a decision that the wider curve would never be built, rather than a decision to go ahead and build what they actually did. I agree that without the work at Oxford Road and Piccadilly, this curve (now carrying only one train per hour) was a monumental waste of money and an indictment of the way politicians (don't) plan and fund rail projects.

This has probably been done to death a few dozen times on the HS2 thread. But in short, about 8% of the passengers on HS2 were predicted to be going to Heathrow so it would be difficult to provide a good service there without inconveniencing the much larger number heading for central London. Even if they did that, you'd still not be able to serve all terminals directly. Old Oak Common has a frequent service to all terminals.

What land was released please?

NPR: Let's make Piccadilly the prime station, so we can use parts of HS2 to continue to Liverpool.

It's probably OK if there is a plan and political commitment to build a comprehensive network in a reasonable timescale. Clearly we don't have that in the UK, and if HS2 had been incompatible with the classic network then passengers from the North West to London would be forced to change at Birmingham (and possibly again at OOC) for many years.

So I guess carriers don't have a mouse problem...

Contractors and consultants also have to spend a lot of money putting their bid together, which involves some very detailed planning if they are to reduce the risk of underbidding and losing money. There's always a clause somewhere which says the employer reserves the right to cancel the tender process and the bidder can't then seek any recompense (quite apart from the money being lost if someone else wins). If the government gets into the habit of issuing tenders and then doesn't proceed with the work, the next time they may find that suppliers bid high to allow for the risk premium or just don't bid at all.

I guess the face and the hands could have been original. The mechanism, not so much.

Seeing the ROC at Ashford not in use might only have been a tempory control from France. Presumably they need to use it from time to time to keep the staff current. They may even have scheduled a swap so Tim's visit could be confined to British territory. Interesting that the re-used section of 1974 tunnel only appeared to be a few tens of metres long, although I think there was another set of cast iron segments visible in the distance at one point. If that's all there is then I'd have thought it would have been easier to just get rid of it rather than trying to re-use.

The reasoning for a station at OOC most likely goes back to the original idea of connecting to Heathrow, and I think was entwined with the decision to turn down the third runway and provide better rail connections instead of more domestic flights. A branch there would have been very difficult and expensive, and would only have served one or two terminals directly so many passengers would have needed to change again. IIRC only about 8% of passengers were expected to head there anyway and it was quite hard to develop a service pattern that provided for them without inconveniencing everyone else. Early designs included provision for a future junction towards Heathrow, just south of the Chiltern tunnels I think, but it was deleted. A stop at OOC allows passengers access to any terminal at Heathrow without a further change of train.

Part of the difference in China may be that they have more engineers in positions of political power.

Part of the claimed benefit of downsizing Euston HS2 from 11 to 10 platforms was the saving of time and cost, because it allowed the station to be built in one phase instead of two... Anyway, as mentioned, construction is well under way and the parts of the existing station within the footprint of the 10 platforms have already been demolished.

We now know that the Russians had far better maps of UK military sites than the British public was allowed to have.

The line from Chester to Warrington was genuinely a joint operation as part of the Birkenhead Railway. The GWR had its own warehouse at Liverpool Road, now part of the Museum of Science and Industry. https://www.pressreader.com/uk/heritage-railway/20210416/282342567660431

Unlikely to be maglev. The cable-hauled peoplemovers at Birmingham and now Luton are limited to one vehicle per track, as the vehicle is fixed to the cable, and this probably wouldn't be enough capacity for a longer route with several stops. There's apparently now a variation on cable-hauled that allows vehicles to let go of the cable and switch tracks, but my money would be on a rubber-tyre vehicle with on-board motors, as seen at airports such as Stansted.