Sleepers (ties) are increasingly made up of prestressed concrete, though metal and teak sleepers are still in use on a few lines.
Metal and teak sleepers are still in use on a few lines. Sleepers (ties) are mostly made up of prestressed concrete.
Sleepers (ties) are mostly made up of prestressed concrete. Metal and teak sleepers are still in use on a few lines.
Sleepers (ties) are mostly made up of prestressed concrete. Metal and teak sleepers are still in use on a few lines.