P4 gauge
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(Redirected from P4 scale)
P4 gauge, also known as protofour, 4mm finescale, Scalefour and S4 is a model railway standard of 4mm scale and accurate 18.83 mm gauge track. As the name implies, P4 gauge is accurately to scale for 4 mm scale modelling, while other track gauges (such as OO gauge and EM gauge) used for standard gauge prototypes are less accurate approximations.
As well as a track gauge, P4 also specifies the exact wheel profile and track parameters to use, which are largely an exactly to scale version of real life standards.
P4 is only used in Britain, like OO and EM. Irish broad gauge is also modelled at 4mm scale with 21mm gauge track to P4 standards.
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