are that the trackwork has to be laid and built to very close tolerances and needs to be flat. If this is not the case then the reliability of rolling stock on the trackwork is compromised leading to poor running and derailments. This problem can, to an extent, be mitigated by the use of some form of suspension system in the locomotives and rolling stock used on the layout. There are different ways to do this and reference to one of the societies supporting modelling to this standard is recommended. Conversion to EM and P4 00 models can be converted to work on EM or P4 by replacing or reprofiling wheels, fitting the correct width axles and moving the locomotive or carriage frames outward to suit. Modern products from Hornby, Bachmann UK and others have some element of springing in their suspension to aid this, and many aftermarket chassis kits exist from a variety of vendors such as high level kits, Comet, DJH, and others. Products intended for the more dedicated modeller are generally designed to be buildable to fit any of the three standards, though one side effect of underscale locomotive frames for 00 gauge is that the width between the frames is limited, which can limit the size of electric motor that may be fitted. Irish Broad Gauge Irish Broad Gauge is 5' 3". OO models are available from Bachmann and have previously been available from Lima. P4 standards can also used with a track gauge of 21 mm. Narrow gauge OO9 9 mm gauge (N gauge) track used to model 2'–2'6" gauge prototypes. OOn3 12 mm gauge (TT gauge) track used to model prototypes which were common in Ireland and the Isle of Man. References External links The Double 0 Gauge Association, supports 4 mm modelling using a 16.5 mm gauge EM Gauge Society, supports modelling in both EM (18.2 gauge) and P4 (18.83 gauge) The Scalefour Society, supporting modelling in P4 (18.83 gauge) Diesel and Electric Modellers United, promoting and supporting the modelling of the Diesel and Electric era of the British standard gauge railway system The 009 Society - Supporting modelling 4 mm narrow gauge modelling Scale model scales