What Is The Minimum Curve Radius For OO Gauge Track?

Generally, the recommended minimum radius is determined by the accepted Set Track standards in UK OO gauge modelling. But, similar to 3rd Class seating, the concept of 1st Radius curves is no longer considered to be of any use. So where does that leave us, and what is really the minimum radius for OO gauge track?

Is it possible to have a track with a much tighter curve than the norm? Where would you want tighter curves and what are the pitfalls to avoid? 

Read on, as we straighten things out…

Table of Contents

• What is the minimum curve radius for OO gauge track?
• Where would you use tighter curves?
• What models can use tighter curves?

What is the minimum curve radius for OO gauge track?

Whilst 1st Radius curves ( 371mm / 14.6 inches) do still exist, for most modern locomotives and rolling stock the minimum recommended curve is 2nd Radius (at 438mm / 17.2 inches).

For the traditional trainset layout, on a single board, perhaps using a Hornby TrackMat, if we consider the next size radius as an outer limit/safety margin, then using 2nd radius curves to turn 180° means a minimum board width of at least 1,000mm / 40 inches.  However, this will give very little room outside the track, for scenery or other sidings, so a baseboard width of 1,200 mm / 48 inches is usually seen as most suitable. This can also accommodate 3rd and just about 4th radius curves.  

Of course, should a baseboard be fitted around a room edge, perhaps fixed to a permanent shelf, then the curves can be eased to much larger radii.

Where would you use tighter curves?

For those modelling industrial scenes, such as ports and quaysides, or factories, it is often more convenient to use curves with a much tighter radius. However, this then limits rolling stock to short-wheel-based locos and wagons, but that is often in keeping with the prototype scenario.

This example is from Google Maps, showing a section of Devonport Naval Dockyard.

For those with a more whimsical philosophy, locomotives inspired by the late Roland Emmet can be made using a 0-2-0 configuration. These can negotiate almost unbelievably tight curves, but this only adds to the charm of these eccentric models.

What models can use tighter curves?

There are several new industrial prototype-inspired locomotives now available on the OO market.

From Hornby's Ruston 48ds and Peckett W4, Dapol's B4, Model Rail's Sentinels, and even Bachmann's Wickham Trolley, there will be something to use on a layout with tighter than normal curves.

Of course, diesel locomotives, with 4-wheel bogies, can also run around tighter curves, but the overhang at each end can look somewhat odd.

Keep on Shuntin'