Metrication of the London Underground

The thing is, I travel on the Central Line almost daily for about ten years now but have only seen the 5 mph signs so far. Considering TCR is undergoing a major overhaul it would make sense if this was the occasion to replace the sign.

The old 1995 stock speedo was marked with kph graduations along the top and mph graduations along the bottom, so the speed could be read off in either system, although I believe it displayed the speed in increments of 2 miles per hour. The present TOD, according to this article, shows the speed in mph, but can be reconfigured to use kph with relative ease. (I know it's about the Jubilee line, but I assume it applies to both the 95s and the 96s.) Of course, the TBTC lines do not use lineside speed limit signage, so that would make switching over easier, although I don't doubt that it would cost and would surely require a certain amount of training and familiarisation.

Getting back to the Central line, I'd love to be able to help, domh245, but I'm afraid I haven't a clue! One thing I do know, from another thread, is that Central line trains generally pass through closed stations at 20 kph, not 8, so I'm a little confused by that sign, but I suppose it's primary purpose is to show/remind that the station is closed.

Regarding when the Central line went metric - I don't know that either. Although I'd be equally interested in any details. Obviously there was a time, during the rollout, when the 1992s were operating alongside the 1962s and 1960s. I was under the impression that the 1992s operated under tripcock signalling for some time, while the rollout was completed and the new signalling was installed. Meaning, of course, that the speed was in the hands of the driver. Now the 1992s certainly display the speed in kph presently, and the 1962s used mph traditionally. So I wonder, were the 92s once able to show mph, were the 62s coverted to show kph, or were signs with both units installed?

Roll on the day when it unmetricates!

ISTR reading that the 1973 stock was the first to be designed in metric, and thus the last Imperial stock to be designed would be the 1972 stock, and the last to be built the C77 stock (assuming they used the same drawings as for the C69)

Arguably the two C stock cars rebuilt after 7/7 would be the last to be built to imperial dimensions.

The Northern still uses mph, and I'm pretty sure so does the Jubilee. Having said that, the speeds input by the signallers into the system (for example for a TSR, or a speed ceiling on a specific train) are in kph, albeit with mph displayed alongside in brackets.

The Victoria Line used mph initially, however I recall reading that a subsequent software drop proposed to change to kph. The last I remember is this reading a circular saying this was about to happen, so I presume the change was made. The circular wrongly stated this would be the first railway in Britain to use kph.

Can't see a need to change, everyone's happy with mph.

Well, if that is the case, I appear to have narrow thumbs and small feet! As for distances between cities, whilst it may be difficult to imagine Brum being 160km from London, for the most part, that is because we tend to use imperial units for most things to do with roads. You can always remember that Liverpool to Sheffield is 100km!

As for your final comment, given the 'family friendly' nature of the forum, I can only assume that you are talking about visual display equipment!

The Newcastle Metro used kph from the outset.

I remember being told that the '73 stock was originally designed in imperial then rounded up for metric. Unfortunately, the glass was still manufactured in imperial so the original delivery didn't fit the holes they were supposed to go in. It might be a shaggy dog story, but it wouldn't be that surprising if it were true.