Warning the Thames Barrier - Londonís first line of defence

Environment Agency
Sentinel ER450
Tidal level monitoring and alerts
Industry / Vertical:
Utility/environmental monitoring


Built across a 520-metre stretch of the river, the Thames Barrier is one of the UK’s most recognisable constructions. Completed in 1982, the barrier was constructed to provide a line of defence against river and sea surge events which could cause devastating damage to London. Depending on the extent of a flood defence failure, estimated property damage currently lies between £7.94bn and £12.24bn, so it is critical that the Thames Barrier is able to react immediately to any changes in tidal flow and surges created by increases in atmospheric pressure in the North Sea.


Whilst the aim is to support a more holistic approach to flood risk management through long-term strategic planning, the Thames Barrier responds to more immediate threats of flood. A peak rise in tidal surge, when detected at Southend, will reach the Thames Barrier within just 20 minutes. Installation of the tidal monitoring network across the Thames Estuary was carried out for the Environment Agency by system integrator Serck Controls. In order to ensure the required speed of response to sensor data, The Environment Agency needed a guaranteed, rugged radio network and turned to Wood & Douglas’ Sentinel ER450, a digital outstation radio housed in a compact die-cast enclosure.

By adopting a radio solution, The Environment Agency could ensure an instant transmission of the sensor data to the Thames Barrier control without concerns of using a third party wireless operator, which could be prone to network congestion or failure in an emergency. Due to the ranges involved, the radio network included zones without line of sight, but this was not an issue for the ER450s which contain a buffer memory enabling the data to be received and relayed. This ‘store-and-forward’ capability maintained network speed, sending sensor data from as far as Tilbury Docks and Gravesend to the Thames Barrier in less than a second.

Since completion, the Thames Barrier has been raised in reaction to tidal surges more than 100 times. Despite global warming and a consequently greater predicted rate of sea level rise, recent analysis has recently extended the working life of the barrier until around 2060–2070, with the Sentinel ER450s continuing to provide fast data communication between the sensor network and the Barrier.

  • Mission-critical tidal monitoring and radio alert relay
  • Sentinel ER450s guarantee fast communication without line of sight

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