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
Thanks in advance!
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 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.
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
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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