The concrete industry has hit back at the inaccurate and misleading reporting of the closure of the A4 Hammersmith Flyover, London. The flyover was closed on 23 December following concerns over structural defects and partially reopened to light traffic on 13 January.
The concrete industry has hit back at the inaccurate and misleading reporting of the closure of the A4 Hammersmith Flyover, London. The flyover was closed on 23 December following concerns over structural defects and partially reopened to light traffic on 13 January.
Site investigations have ascertained corrosion of the internal steel cables which help support the flyover, due to salt water ingress from grit laid during winter. The flyover, built in 1962, was originally designed to have under-road heating and was not meant to be gritted. The under-road heating has never operated and, over the last 50 years, salt water due to gritting has steadily seeped into the structure.
The Hammersmith Flyover comprises concrete segmental units post-tensioned with steel cables. The issue of steel corrosion is well understood and modern bridges are designed to ensure that the steel elements are adequately protected. There has been no report of any structural failure of the concrete units themselves despite some headlines incorrectly reporting ‘concrete cancer’ or ‘rotting concrete.’
“Such terms are sensationalist with no general technical basis and have no relevance to this particular structure”, said Andrew Minson, executive director of Mineral Products Association (MPA) the Concrete Centre. “The Hammersmith Flyover is undergoing strengthening works because of a steel corrosion issue not a concrete material issue.”
His comments were underlined by Nigel Jackson, chief executive of the Mineral Products Association, who said: “It is regrettable that concrete, which is such an essential material for both existing and future infrastructure, has been misrepresented in such tabloid terms. It is important that technical issues such as these are reported accurately and with integrity.”
Engineers inserted 100 cameras into the flyover to fully assess the cable damage before undertaking strengthening works. These are expected to take around four months.
