Tunnel Pumped Drainage (TPD) is a mechanical drainage system used to collect and remove water from railway tunnels, particularly at low points where the tunnel cannot discharge effectively by gravity.

Water entering the system may originate from groundwater infiltration, seepage, track drainage, tunnel washing, firefighting activities, equipment drainage and other sources.

The drainage arrangement typically directs water through channels, gullies or drainage pipes to a sump or pumping station located at a suitable low point. Pumps then lift the collected water through discharge pipework to a gravity drainage system, sewer, surface-water network or other approved discharge location.

A Tunnel Pumped Drainage system may include duty and standby pumps, sumps, level sensors, valves, non-return valves, discharge pipework, electrical panels and local control equipment. Pump operation is generally automatic based on water levels within the sump.

Monitoring and alarms may be provided through a PLC, SCADA or other centralized monitoring system to indicate conditions such as high water level, pump failure, power failure or abnormal operating status.

Railway TPD design must consider peak inflow rates, emergency water volumes, pump redundancy, sump capacity, power-supply reliability, maintenance access, blockage prevention and the consequences of system failure.

The system requires close coordination with tunnel civil works, track drainage, waterproofing, MEP systems, electrical power, fire and life safety systems and the external drainage network.

mainline, high_speed, metro, light_rail, freight

Applicable railway tunnel drainage standards; local drainage authority requirements; project-specific tunnel, civil and MEP specifications