A railroad tie/railway tie/crosstie (American English) or railway sleeper (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.Railroad ties are traditionally made of wood, but pre-stressed concrete is now also widely used, especially in Europe and Asia. Steel ties are common on secondary lines in the UK;plastic composite ties are also employed, although far less than wood or concrete. As of January 2008, the approximate market share in North America for traditional and wood ties was 91.5%, the remainder being concrete, steel, azobe (red ironwood) and plastic composite.Approximately 3,520 wooden crossties are used per mile of mainline railroad track in the US (distance between ties is nominally 18 in (46cm) including one tie and the crib), 3,520 per mile (2,190/km) (40 per 60 )ft or 18.3 m rail) on main lines in the UK. Rails in the US may be fastened to the tie by a railroad spike; iron/steel baseplates screwed to the tie and secured to the rail by a proprietary fastening system such as a Vossloh or Pandrol are commonly used in Europe.

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