Why did the UK not pursue double deck trains?

[Gostav]

There were a kind of double-decker train operated by Japanese private railway: the Kintetsu Railway 20100 series, which had 2,800 mm wide and 4,065 mm high. Judging from the technical specifications alone, this double decker train should be also fit with UK railways.

オリジナルのアップロード者は日本語版ウィキペディアのJr223さん - ja:ファイル:Kintetsu-20100.JPG, パブリック・ドメイン, https://commons.wikimedia.org/w/index.php?curid=54754177による

 

[zwk500]

There were a kind of double-decker train operated by Japanese private railway: the Kintetsu Railway 20100 series, which had 2,800 mm wide and 4,065 mm high. Judging from the technical specifications alone, this double decker train should be also fit with UK railways.

Max UK carriage crown height at centreline is 3,910mm (see: http://www.trainweb.org/train-research/loading_gauges/c1/c1.html, link to the C1 Loading Gauge Profile). The max width is not the problem, but the width below platform level, which means the lower deck would need to be a lot narrower.

 

[Gostav]

Max UK carriage crown height at centreline is 3,910mm (see: http://www.trainweb.org/train-research/loading_gauges/c1/c1.html, link to the C1 Loading Gauge Profile). The max width is not the problem, but the width below platform level, which means the lower deck would need to be a lot narrower.

That is similar in Japan, l didn't find the loading gauge standard for Kintetsu Railway but should same with that diagram from Wiki. Blue part means "Local railway construction regulations" enlaced in 1919 and Railway construction regulations" enlaced in 1910, grey part means "Rules of ordinary railway structure" enlaced in 1987. All have narrow limits from below the platform part.

 

[30907]

ISTR the timetabling carefully avoided the height of the peak

And checking the 1963 workings (peak direction):
6.57 Dartford via Sidcup to CHX 7.41
8.26 Crayford ditto to CST 9.2
3.27 CST Dartford via Sidcup
5.23 CST Slade Gr via Bexleyheath
7.7 CST Dartford ditto
So only one high peak out of 5.

 

[Deepgreen]

I’m assuming this photo is genuine - apparently at London Charing Cross in the late 1940s.

Given some infrastructure on certain routes appears to have been able to cope at that time (bridges, tunnels etc) why do we not have these today?

View attachment 159687

Certainly genuine - Bulleid produced two 4 car DD units, which actually were more like one and a half decks. The upper areas had no ventilation and I can attest that they were stifling, as I was taken on a run on them in August 1971, their final year of operation, and even as a child I was boiling! They were generally used for peak hour workings only.

== Doublepost prevention - post automatically merged: 12 Jun 2024 ==

The 4DD has a chequered history (and yes the photo is genuine). It wasn't really double-deck but as you can see from the photo a staggered arrangement. You'd have the upper passenger's feet between lower compartment's head height.
It didn't go anywhere because it was cramped, expensive to maintain and had low dwell times compared to a single deck train.

is a contemporary Pathe newsreel, and despite the optimistic tone, you can see the problems.

High dwell times...