The King George V lock in London’s Royal Docks has three sets of mitre gates in a barrel approximately 243.8m long. The outer mitre gate, installed around 30 years prior, was due for a refurbishment of the gate and repairs to the seals and cill.  

The site also had a flood defence gate owned and operated by the Environment Agency, which took up a considerable amount of developable land. The refurbishment work presented the opportunity to also replace the existing flood gate with a new flood defence.

Beckett Rankine was commissioned to undertake feasibility studies into alternative flood defences. The chosen option was a Reverse Mitre Flood Gate to replace the existing outer lock gate, which offered the greatest flood protection with the smallest area flooded of the options provided.  

The design also considered options to better support the gates during flood activity and prevent them from opening under the additional force. We recommended the addition of drop pins and lockable rams on the gate.  

We were then tasked with the scheme design and budget cost. This included a variety of elements, such as models for buoyancy and stability of the gates, outline designs for the sill, pintle and top strap, and concept designs for the mechanical and structural operation of the gates.