Looking for the N-scale measurements of various NEM (Normen Europäischer Modellbahnen) standards? I made JPG files of them here. Feel free to download and refer.
Note: depending whether you are using code 55 or code 80 tracks, with or without cork roadbed and extra under-layers, these measurements below are always from the top of the rail. So if you have a 3mm cork on your plywood base, and using code 55 PECO tracks (3,1mm), you can add 6,1mm to these height measurements (if you are measuring from the plywood base)
SO: Schienenoberkante (top of rail)
NEM102 defines the clearance (loading gauge) on a straight track. Read in conjunction with NEM301, which defines the clear boundaries of a model, NEM102 shows the extra spaces around the model so as to avoid hitting another model on a parallel track, signals or bridge support structures.
NEM103 defines the clear space boundaries on curves or transition to a curve. For N-scale, this is extra 3-5mm on either sides of the model, depending on the radius of the curve. The smaller the radius, the more space up to 5mm would be recommended. This is important if you are running modern day loco, wagon or coach (up to 27,2m). Catenary masts and signals place along curved tracks would avoid being hit by the side of the model if these measurements are observed.
NEM111 requires the observation of the radius of curved tracks for various categories of models (loco, wagon, coach). The first row shows the minimum radius for reliable operation. For the Wagon group C, minimum radius is 270mm (27cm).
Recommended minimum radii of the innermost track (for Wagon group C) are:
– secondary track at stations: 315mm
– main track on branchlines: 360mm
– main track on mainlines: 405mm
NEM103 specifications for Standard Wagon Groups
Wagon group A: 125mm length (20,0m)
Wagon group B: 151mm length (24,16m)
Wagon group C: 170mm length (27,2m)
NEM112 specifies a minimum 25mm between track centre of 2 parallel tracks at open space while increases to 28mm at stations. At curved tracks, track spacing, measured from track centres, varies from 35mm (for 225mm radius) down to 25mm (for radius above 550mm) (these applied up to Wagon group C). As most layouts could have between 50cm and 100cm width, keeping a distance of 29 to 33mm track distance is recommended.
On my diorama, even with 33mm track spacing, the overhangs of ICEs (Wagon group C) were obvious and two speeding trains could potential “rub” each other.
NEM114 defines up to 0,6mm elevation on the outer track is allowed. Photo of a model loco with and without superelevation.
NEM201 applies to those who want to operate pantographs or where the power source comes from the catenary. The minimum distance between top of rail (SO) and the catenary is 34mm (crossover underpass structures, low tunnels) or up to 40mm (on open tracks). Typically at railway stations, the height is 38mm from top of rail.
These are just some of the important measurements to observe. For more, check the MOROP website (in German/Deutsch)