What are the minimum vertical clearances for model trains – British standards

Model Railway Standards

Don’t run the risk of having your trains crash into tunnel roofs. Build to British standards for minimum vertical clearance and train heights and keep your models safe.When building tunnels and over bridges for model trains to pass through making sure the train can pass through clearly without crashing in the top of the structure is obviously vital.

How high should a bridge or tunnel be for N, OO, HO scale?

Luckily, a set of standards that define this were devised in 1950 and if you keep to these you (or more importantly your trains) will be safe.

The standards are from the British Railway Modeling Standards Bureau and give exact dimensions for all the main British scales.

From track to train top these are:

N (1/148)




For reference, the protocol height (that of real trains) is 13ft.

So when planning and building a tunnel or bridge, measure from the top of the track rails to, say 54mm in the case of OO gauge, and go above this and you’ll be good.

Personally, I’d also allow a little extra room for access should you need to get your fingers or tool under there for whatever reason, not that our trains ever derail in tunnels… 🙂

As a final note, the history behind model railway standards, the British Railway Modeling Standards Bureau  – my copy of one of their publications is seen above – and the hobby and the History of OO Gauge by Stephen Siddle is fascinating reading.

> A final, personal, note: I spend a huge amount of time testing, photographing, writing and researching techniques for these articles and pay for all the running costs of MRE out of my own pocket. If you found this article useful you can support me by making a donation on my fund-raising page. Thanks and happy modelling, Andy.

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Founder of ModelRailwayEngineer, Andy Leaning

Andy is a lifelong modeler, writer, and founder of modelrailwayengineer.com. He has been building model railways, dioramas, and miniatures for over 20 years. His passion for model making and railways began when he was a child, building his first layout at the age of seven.
Andy’s particular passion is making scenery and structures in 4mm scale, which he sells commercially. He is particularly interested in modelling the railways of South West England during the late Victorian/early Edwardian era, although he also enjoys making sci-fi and fantasy figures and dioramas. His website has won several awards, and he is a member of MERG (Model Railway Electronics Group) and the 009 Society.
When not making models, Andy lives in Surrey with his wife and teenage son. Other interests include history, science fiction, photography, and programming. Read more about Andy.

Afflliate disclosure:The links on this page may take you to carefully selected businesses, such as Hornby, Amazon, eBay and Scale Model Scenery, where you can purchase the product under affiliate programmes. This means I receive a small commission on any orders placed although the price you pay does not change. You can read my full affiliate policy here. I also sell my my own ready to use, pre-made and painted buildings and terrain features. browse the range.

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