What kinds of sleepers are used by IR?
Cast iron sleepers (‘CST-9’) are widely used. They are not very suitable for high-speed traffic and so are not usually seen on the mainline BG sections. The earlier ‘pot sleepers’ were especially prone to problems; newer cast iron sleepers (with ends that have two pockets) are much more laterally stable. Steel trough sleepers (‘ST’) are very common, especially for many high-traffic BG routes. Steel sleepers of various designs have also been used for MG and (by reusing discarded MG sleepers) for NG too. IR also uses prestressed (pretensioned) concrete sleepers in many areas. Some are monobloc prestressed concrete sleepers, while others are two-piece reinforced concrete sleepers. These came into use in the 1970s, however the twin-block concrete sleepers have gone out of use while the monobloc sleepers continue to be deployed. Standard prestressed concrete sleepers are available for a number of configurations for use in turnouts. Some post-tensioned concrete sleepers do exist on some stre
