Track spacing (parallel track distance)

Track spacing is the distance between the centrelines of two parallel tracks. Every track system has a standard spacing (in H0 e.g. 61.9 mm for Piko A, 76.5 mm for Roco geoLine, 77.5 mm for Märklin C track) that turnouts, curve radii and crossings are designed around. Sufficient spacing matters so long vehicles do not touch in curves.