HALCROW has secured a design contract for one of the world's largest flood protection barriers.
It will update designs for the US$385M scheme, which stretches 25.4km across Neva Bay near St Petersburg in Russia.
The embankment structure is intended to prevent the twiceyearly flooding of the Russian city - and carry a six lane highway.
The St Petersburg barrier will incorporate an embankment with eight sluice gates and two navigation channels.
A tunnel will transport the highway beneath the main 200m wide shipping channel.
A pair of 130m long curved rotating gates, thought to be the largest of their type in Europe, will protect this key cargo route. This opening is over six times wider than those on London's Thames Barrier.
The shorter navigation channel will have a vertical hydraulic lift bridge to raise the highway 8m and allow shipping to pass beneath.
Work on the project began in the 1980s but construction was halted in 1987 amid fears that it would prevent untreated sewage from reaching the Baltic.
Since then, the Russians have built new treatment plants to alleviate the problem, said Halcrow director David Birch.
Halcrow's main task is to check that the designs still conform to modern international codes. This was demanded by the European Bank for Reconstruction & Development (EBRD), which has lent US$230M to the scheme.
Birch expects all mechanical and electrical works to be updated although the civils designs are well advanced.