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> Britain is max 200kph (125mph) currently although there is infrastructure designed for 225kph (140mph) on conventional lines though this is not permitted any

> Britain is max 200kph (125mph) currently although there is infrastructure designed for 225kph (140mph) on conventional lines though this is not permitted any more. It’s not correct to say that trains circulate at close to top speed a lot of the time as they share tracks with freight and commuter and there is a lot of congestion on uk lines. I was referring to Britain's adoption and pervasive use of its InterCity 125 trains. https://en.wikipedia.org/wiki/InterCity_125 https://en.wikipedia.org/wiki/InterCity_125 The interesting aspect of the InterCity 125 was the fact that, instead of going with an optimized record breaking train, British Rail went the other way around and optimized their track layouts to allow an unimpressive train to achieve what was at the time unmatched commercial speeds.

willyt 3y ago
No you’ve got it the wrong way round the Intercity 125 was an impressive feat of engineering designed very quickly as a temporary stopgap while lines were electrified and still holds the record for world’s fastest diesel train. It was a side project of the engineers that were designing the Advanced Passenger Train that was being developed at the time, which was supposed to be able to run at up to 150mph on conventional routes using tilting technology. The intercity 125 incorporated a lot of the lightweight construction research that was done for APT. Not much was done to the track to enable higher speed running, some resignalling and very very occasional route realignment for higher speeds. The intercity 125 achieved better times by being more lightweight and having faster acceleration than conventional locomotive hauled trains of the time, but it was only 15mph faster than the conventional trains. Most of Western Europe has standard lines with up to 125mph running, it is not uncommon. E.g a lot of the old non-tgv line between Paris and Bordeaux supports trains running at up to 200kph (125mph) Likewise 200kph running is common in Germany with conventional trains. The track in the UK was not special, quite the opposite as when the 125 was introduced we still had a lot of victorian style jointed rails that had been obsolete since the 1950’s. Britain was slow to upgrade to continuous welded rail, it wasn’t gone from all main lines until the 1990’s.

willyt 3y ago

No you’ve got it the wrong way round the Intercity 125 was an impressive feat of engineering designed very quickly as a temporary stopgap while lines were electrified and still holds the record for world’s fastest diesel train. It was a side project of the engineers that were designing the Advanced Passenger Train that was being developed at the time, which was supposed to be able to run at up to 150mph on conventional routes using tilting technology. The intercity 125 incorporated a lot of the lightweight construction research that was done for APT. Not much was done to the track to enable higher speed running, some resignalling and very very occasional route realignment for higher speeds. The intercity 125 achieved better times by being more lightweight and having faster acceleration than conventional locomotive hauled trains of the time, but it was only 15mph faster than the conventional trains. Most of Western Europe has standard lines with up to 125mph running, it is not uncommon. E.g a lot of the old non-tgv line between Paris and Bordeaux supports trains running at up to 200kph (125mph) Likewise 200kph running is common in Germany with conventional trains. The track in the UK was not special, quite the opposite as when the 125 was introduced we still had a lot of victorian style jointed rails that had been obsolete since the 1950’s. Britain was slow to upgrade to continuous welded rail, it wasn’t gone from all main lines until the 1990’s.