What if 1,100mm was the standard platform height?

[Sorcerer]

So obviously Britain's railway network has historically had varying platform heights due to being built by different companies with different standards. But in general, 915mm is the norm for most platforms with the notable exceptions being Heathrow Express platforms at the terminal stations along with the Elizabeth Line core being at 1,100mm and with HS2 planned to be 1,115mm for true step-free access. But at present 1,100mm is the closest to level platform heights, and it got me wondering, what if 1,100mm became the norm for platform heights instead of 915mm? What was it that made 915mm the norm and how different would the railways be in terms of rolling stock (such as appearances) and the rail infrastructure (such as design and platform designs) if we went with 1,100mm? Setting aside the cost that would come with converting platforms to a more step-free height, what would change if the network platforms were converted and how different would our railways be if we had done long ago?

 

[AM9]

So obviously Britain's railway network has historically had varying platform heights due to being built by different companies with different standards. But in general, 915mm is the norm for most platforms with the notable exceptions being Heathrow Express platforms at the terminal stations along with the Elizabeth Line core being at 1,100mm and with HS2 planned to be 1,115mm for true step-free access. But at present 1,100mm is the closest to level platform heights, and it got me wondering, what if 1,100mm became the norm for platform heights instead of 915mm? What was it that made 915mm the norm and how different would the railways be in terms of rolling stock (such as appearances) and the rail infrastructure (such as design and platform designs) if we went with 1,100mm? Setting aside the cost that would come with converting platforms to a more step-free height, what would change if the network platforms were converted and how different would our railways be if we had done long ago?

I would think that 915mm (being the equivalent of 1 yard or 3 ft) was adopted as a round figure in the vicinity fo what was practiv#cal for much of the railway, (when the standard coach wheel was around 3ft also. Similarly as 1100 or 1115 mm is around three feet 8 inches as near as makes little difference. Platform height above rail is nowhere as critical as track gauge, even where accessibility is concerned.

 

[zwk500]

The height itself is only one part of the profile, of course. UK platform edges are also considerably closer to the rail edge than most European networks. If platform heights were harmonised to train floor heights there would likely be a lot of curved platforms requiring to be cut back, as the curve out from the lower section is quite pronounced on UK rolling stock. Or, of course, all platforms needing to be straightened. Which might cause problems at Bristol, York, Newcastle, Carlisle, etc.

 

[Bletchleyite]

The height itself is only one part of the profile, of course. UK platform edges are also considerably closer to the rail edge than most European networks. If platform heights were harmonised to train floor heights there would likely be a lot of curved platforms requiring to be cut back, as the curve out from the lower section is quite pronounced on UK rolling stock. Or, of course, all platforms needing to be straightened. Which might cause problems at Bristol, York, Newcastle, Carlisle, etc.

Also rolling stock step height does vary. The CAFs seem to be noticeably higher than e.g. 15x. If you're having to build new stock to a standard height it might as well be 915mm and save money changing platforms.

 

[Sorcerer]

The height itself is only one part of the profile, of course. UK platform edges are also considerably closer to the rail edge than most European networks. If platform heights were harmonised to train floor heights there would likely be a lot of curved platforms requiring to be cut back, as the curve out from the lower section is quite pronounced on UK rolling stock. Or, of course, all platforms needing to be straightened. Which might cause problems at Bristol, York, Newcastle, Carlisle, etc.

Sounds like Berkhamsted would be a real nightmare with a curved platform and tilting trains then. Obviously even in the case of 1,100mm standard the Pendolino wouldn't be level boarding since the floor height is higher, but that would be an exception rather than a rule. Makes me wonder if a higher platform height would need a narrower body though in order to account for the tilt profile.

 

[zwk500]

Also rolling stock step height does vary. The CAFs seem to be noticeably higher than e.g. 15x. If you're having to build new stock to a standard height it might as well be 915mm and save money changing platforms.

Indeed. Although with the standard diameter of a Railway Wheel by the UIC definition being 920mm I'd be tempted to go for a standard floor height of e.g. 950mm which although not true level boarding would be closer while avoiding any problems of having to 'bump' internal floors over bogies or narrow squeezes as you can find on some continental stock.

Sounds like Berkhamsted would be a real nightmare with a curved platform and tilting trains then. Obviously even in the case of 1,100mm standard the Pendolino wouldn't be level boarding since the floor height is higher, but that would be an exception rather than a rule. Makes me wonder if a higher platform height would need a narrower body though in order to account for the tilt profile.

Or potentially shorter individual vehicles. Berkhamsted would indeed be a right pain, although it's probable tilting won't be around forever as HS2 will remove the pressure for classic WCML journey times to be maximised.

 

[Bletchleyite]

Indeed. Although with the standard diameter of a Railway Wheel by the UIC definition being 920mm I'd be tempted to go for a standard floor height of e.g. 950mm which although not true level boarding would be closer while avoiding any problems of having to 'bump' internal floors over bogies or narrow squeezes as you can find on some continental stock.

960mm is what Stadler uses for UK "level boarding" at 915mm platforms. It's actually 45mm above platform, but actually means a very small step up from the platform to the moving step and another small one that allows for a strong enough* body panel above the step. These slight undulations are fine for most wheelchairs and prams.

* Allegedly (the Class 777 entered the chat )

 

[zwk500]

960mm is what Stadler uses for UK "level boarding" at 915mm platforms.

Well within the margin covered by my 'e.g.'

It's actually 45mm above platform, but actually means a very small step up from the platform to the moving step and another small one that allows for a strong enough* body panel above the step.

45mm is still a hell of a lot better than today, especially for people who can walk but struggle with steps. 45mm is probably fine for prams and most cycles although probably isn't suitable for wheelchairs, hence the 2-step arrangement you describe.

 

[Bletchleyite]

45mm is still a hell of a lot better than today, especially for people who can walk but struggle with steps. 45mm is probably fine for prams and most cycles although probably isn't suitable for wheelchairs, hence the 2-step arrangement you describe.

Yes, a single 45mm step is probably too much for a wheelchair, but fortunately we need gap bridges anyway, so two 22.5mm steps will tend to be fine for almost everyone. You need a decent structural floor above the step anyway, so you have to have at least one step of about 20mm at least.

You don't need that for a fixed step of course, but a fixed step doesn't close gaps on curved platforms (see the Isle of Wight, which is very nearly level vertically but still requires a ramp as there's a gap, or similarly the London Underground S stock).

 

[Mcr Warrior]

How high (low) are platforms at some secondary / tertiary stations, that have required the installation of "Harrington humps" or similar contrivances?