Components, systems and materials › Railway track components › Concrete sleeper
Concrete sleeper
What it is
A concrete sleeper is a prestressed concrete beam laid across the track that holds the two rails at the correct gauge and tilt and passes wheel loads into the ballast.
Where it is used
Main-line, freight, suburban and metro ballasted tracks; special sleepers at turnouts and bridges.
How it works
Rail seat loads push the sleeper down into the ballast, which pushes back unevenly, so the sleeper bends: sagging under the rail seats and hogging at the centre. Prestressing keeps the concrete in compression under these cycles. Cast-in inserts anchor the elastic fastenings, and pads under the rail add resilience.
Types
- Mono-block prestressed sleepers
- twin-block sleepers joined by a steel tie
- wide sleepers and bearers for turnouts
- sleepers with under-sleeper pads
Materials
High-strength concrete, high-tensile prestressing wires or strands, cast-in shoulders or inserts, rail pads and insulators.
Design checks bending at rail seat and centre, under static and dynamic wheel loads with impact factors, plus fatigue and handling. Sleeper spacing and ballast depth together control the pressure on the formation. Factory production is controlled by testing of samples to the specification.
Installation and QA steps
- Manufacture in a controlled factory with long-line pretensioning.
- Test sample sleepers for bending and fatigue.
- Lay at specified spacing and square to the track.
- Fit fastenings and check gauge.
- Pack ballast by tamping and stabilise before full speed.
- Rail seat cracking from impact loads
- centre-bound cracking when ballast under the centre is too firm
- damaged inserts and loose fastenings
- abrasion at the rail seat
Codes cited
- EN 13230 (series) (Europe): Concrete sleepers and bearers for railway track.
- Indian Railways Permanent Way Manual (India): Standards and practice for track laying and maintenance.
Cited by number only. We do not reproduce code text, tables or figures.
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