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An alternative to conventional individual sleepers (or ties) resting on ballast for railway lines is the use of a continuous reinforced concrete slab. The rails are mounted in chairs set into the slab or continuously fixed within the slab itself. In the UK the generic name for the system is ‘Slabtrack’. Long lengths of slab can be cast using automated machines (see Construction/In situ methods/Horizontal slipforming) or using conventional formwork. Alternatively they can be precast. To date there have been limited applications for main line railways in the UK, but concrete slab has been more widely used for light rail and urban tramway schemes.
The system has several advantages over the traditional approach. The concrete slab is generally shallower and lighter than sleepers and ballast. The reduced depth has obvious advantages in tunnels, leading to increased headroom. Maintenance should be significantly lower.
Slabtrack has a higher initial cost than sleepers and ballast but this is offset by the reduced maintenance requirement. It is estimated that the two systems are comparable over a period of 6 to 12 years, depending on the application.
Acknowledgement: The Concrete Society