The illusion of width: maximising carriage space in the British loading gauge

[Clansman]

Given the constraints of the loading gauge, I can't help but notice certain designs which contribute to the feeling of a much larger or wider feeling in rolling stock interiors.

For starters, we have seen previous BREL rolling stock designs which maximise coach width at 9ft 3inch, with more modern designs currently being more narrow with the likes of the IETs at 8ft 10 inches or the 700s at 9ft 2inch.

I guess first of all, what are the modern design constraints that restrict width down to under the 9ft 3inch that has previously been achieved (crashworthiness? route-specified guage clearence? space for onboard technology?) - and by extension why have previous widths not been achieved?

Secondly, given these constraints, what are some design features which contribute to the illusion of width?

I am aware of the usual constraints around tilting technology as well as raised floors for engines on diesel stock (though previous BREL units have circumvented this as the 150s show with their slower top speeds and acceleration), and that carriages typically over 20m in length require to be narrower or tappered to still fit. Additionally, I personally feel that higher and longer windows contribute to feeling more spacious in carriages, though I know this is subjective.

What are everyone elses thoughts on this?

 

[janahan]

Length of each carraige is a factor too. If the carraige is longer, it has to be a little narrower to fit the same LG around corners. Articulated carraiges, with shorter segments potentially allow a greater width (such as the new tube trains, and trams)

 

[Peter Mugridge]

Visual design of the interior is also important.

The original Mk 3 interior had sideways ceiling lights, for instance. After refurbishment they had lengthwise lighting fitted - which immediately made them feel narrower because of the perspective effect.

There are many other visual tricks which can be used to give an impression of greater space, but they are rarely used properly, if at all.

 

[coppercapped]

Given the constraints of the loading gauge, I can't help but notice certain designs which contribute to the feeling of a much larger or wider feeling in rolling stock interiors.

For starters, we have seen previous BREL rolling stock designs which maximise coach width at 9ft 3inch,

A minor correction, the 9ft 3in maximum width dimension was over the door grab rails and handles, the body width for the C1 carriage profile was 9ft maximum. There is a scan of a drawing of a Mk3 coach (which I found somewhere on the world wide web some years ago but no longer have the URL) dated 7 May 1971 giving the maximum external dimensions. This showed the maximum width over the panel at waist level as (erring on the side of caution) 8ft 11 7/8in.

with more modern designs currently being more narrow with the likes of the IETs at 8ft 10 inches or the 700s at 9ft 2inch.

I guess first of all, what are the modern design constraints that restrict width down to under the 9ft 3inch that has previously been achieved (crashworthiness? route-specified guage clearence? space for onboard technology?) - and by extension why have previous widths not been achieved?

Realistically there has been no great change in the external dimensions. The internal dimensions of stock built with double walled aluminium extrusions could be less due to the extra thickness of the structure compared to a thin steel skin welded to a frame. If one allows for the thickness of insulation material and internal facings I suspect, but don't know, that the true difference in internal width is marginal. Some designs of trains have longitudinal trunking along the wall which will reduce the floor width.

Secondly, given these constraints, what are some design features which contribute to the illusion of width?

I am aware of the usual constraints around tilting technology as well as raised floors for engines on diesel stock (though previous BREL units have circumvented this as the 150s show with their slower top speeds and acceleration), and that carriages typically over 20m in length require to be narrower or tappered to still fit. Additionally, I personally feel that higher and longer windows contribute to feeling more spacious in carriages, though I know this is subjective.

What are everyone elses thoughts on this?

 

[swt_passenger]

One of the narrowest vehicle bodies around is the 23m 444 at 2.688m. That value is from the carriage data plates, many books give incorrect widths, my P5 books state 2.8m.

But when you‘re in one I think most people don’t realise they’re so narrow, I think because the overall squareness of the body shape, and general lack of obstructions, makes them feel at least as wide as a 450. Both SWR Desiro classes seem wider to me than comparable 20m units operating in the south, such as 377s.

 

[Mikey C]

One of the narrowest vehicle bodies around is the 23m 444 at 2.688m. That value is from the carriage data plates, many books give incorrect widths, my P5 books state 2.8m.

But when you‘re in one I think most people don’t realise they’re so narrow, I think because the overall squareness of the body shape, and general lack of obstructions, makes them feel at least as wide as a 450. Both SWR Desiro classes seem wider to me than comparable 20m units operating in the south, such as 377s.

Plus the 444 have "comfy" 2+2 seating, while the 450s have 2+3 seating, so the former will automatically feel less cramped.

The Electrostars and Turbostars bodyshells taper in, making them feel more cramped than the Desiros.

 

[py_megapixel]

The Civity stock on Northern feels considerably more spacious that the Sprinters and 319s it replaced. I think the plug doors really help here as it means no door pockets are necessary - there can be windows down the whole length of the train and thus lots of natural light. The design of most older LU stock where the door slid into the gap between the two panes of a double-glazed window was quite good in this regard. I wonder why it wasn't replicated on the mainline?

I'd love to see what a 323 looks like with 2+2 seating. Would probably feel very wide as well.