The special galvanised chains, which are draped at approximately 5m intervals from eyebolts securely fastened to the river bank wall, are designed for a person to grab hold of if they accidentally fall into the water, particularly where the river flows quickly. Three rows of chains are placed on top of each other at different heights according to the tidal range and the nature of the muddy river bottom.

Cosalt will also be installing fixed ladders at regular intervals along the chains.

This is the second time Cosalt's Lowestoft branch has won a contract to install river grab chains in London. Prior to the Millennium celebrations, Lambeth Borough Council commissioned the company to install approximately 4,500m of chain on the south bank of the Thames between Westminster Bridge and Vauxhall Bridge.

The work is logistically complex, mostly done on site from a riverboat or barge working around the tides. Cosalt has recommended a maintenance package to the Corporation of London to inspect chains and fixings regularly, ensuring they are kept in good condition.

MJ Information No: 16808