What is P4 (Protofour)?

P4 (also known as Protofour) is as true to the scale of 4mm to 1ft (1/76 scale) as you can get, giving a true representation of a properly scaled OO gauge railway.

This is what OO gauge should have been in the first place rather than manufactures compromising and utilising existing 16.5mm HO track.

The track distance on P4 is actually 18.83mm rather than the standard OO gauge being 16.5mm.

If you were to place a P4 engine next to a standard OO the first thing you will notice is the wheels are larger on P4 giving true model scale. The forerunner of these exact standards was EM which is the abbreviation of eighteen millimetres, that being the distance between tracks.

There are a few things to be aware of when venturing into P4: there are very few manufacturers catering for the P4 purists amongst us, meaning very few off the shelf parts being available. You will need longer axles for your train. You will also have to kit bash/scratch build chassis/bogies to allow for running on a wider track.

Talking of track, you will also need to make your own track, as no-one actually makes that gauge of track. This obviously includes points as well.

If you are that way inclined, your first contact should be the Scalefour Society.