OO scale platform height?

Hi all..
Can someone please tell me the correct height for a typical british OO/HO scale platform please?
I'm scratchbuilding a steam era layout based aorund hornby rolling stock
e.g. Flying Scotsman, Brittania, pullman coaches, etc. and this is the one dimension that has eluded me thus far.
Perhaps just the measurement of a hornby platform whould suffice, for starters.
Thanks in advance!
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Craig
Normal for the prototype would be 3ft (12 mm in 00) *above rail level*. Some older platforms could be lower than this.

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Roderic Cameron

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Roderic Cameron wrote:

The OP might like to look at a diagram, showing the Minister of Transport's Requirements in 1950. This is on my Transport Eclectica site at <
http://www.joyce.whitchurch.btinternet.co.uk/clear950.gif . How you modify this to accommodate OO gauge rolling stock is beyond me though!
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Joyce Whitchurch, Stalybridge, UK
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Joyce Whitchurch wrote:

Just convert the measurements. 4mm = 1ft, ie, 1 foot on the protoype 4mm on your layout. IOW, redraw the diagram with millimeter dimensions.
Two problems: A) the fact that British OO uses 4mm scale on 16.5 mm track; B) the fact that model curves are much to sharp, and hence the overhang of the carriages is very large.
A) Wrong track gauge for 4mm scale. Commercial UK OO gauge is 16.5 mm, which is too narrow. It should be 18.83mm, or 2.33mm wider. Thus, measurements from the outer edge of the rail must be adjusted by adding 2.33/2 or 1.16mm. (I would round this up to 2.5mm). Measurements from the track centre line will not be affected, however, as the bodies of the rolling stcok are the proper width.
B) Effect of sharp curves When a carriage enters a curev, its ends overhang on the outside of the curve, and its middle overhangs on the inside of the curve. Result: the carriage needs more track-side clearance on both sides of the curve. This means that the platforms have to be set further away from the track on curves.
On straight track, or on very wide curves (upwards of 6ft radius or so), you can scale the clearance diagram measurements exactly. On sharper curves, you have to allow additional clearance for high platforms. If the platforms are level with the steps, there will be ugly gaps between the platform and the carriage at the ends. If you set your platform height just below the steps, you can bring the platform edges closer to the track - just allow room for the bogies, and for long-wheelbase engines to clear the platform. Won't be exact prototype for modern image, but looks better.
Hope this helps.
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Thanks to all who posted. You've been a big help...

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hi Craig - I too am designing a steam era layout so if you'd like to keep in touch that'd be great - I have a few ideas and am sure you would..... might be some good sharing to be had..... just shoot me an email (remove the obvious)
Cheers
Steve

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http://www.the-dormouse.org/scales2.php may help
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All the best,

Chris Wilson
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According to the latest edition of the Mid Hants News (and a report on the lengthening of the platforms at Ropley), the Railway Inspectorate were insisting on a platform height of 3' above the railhead. However, the Inspectorate has relaxed this back to 2' 6". (Anybody visiting Alresford station will notice that the platform extension at the Winchester end is higher than the original). If this doesn't help, I suggest you build the platform so that its top is marginally below the passenger footboards on the coaches. Hope this helps, David Costigan

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