A railroad tie, crosstie (American English), railway tie (Canadian English) or railway sleeper (Australian and British English) is a rectangular support for the rails in railroad tracks. Generally laid perpendicular to the rails, ties transfer loads to the track ballast and subgrade, hold the rails upright and keep them spaced to the correct gauge. Tie spacing may depend on the type of tie, traffic loads and other requirements, for example 2640 concrete ties per mile on North American mainline railroads to 2112 timber ties per mile on LMS jointed track.