I was interested to read the article about the discovery of corrosion on the suspension cables of the 'old' Severn Bridge (NCE 13 July).
As a reasonably regular traveller over this bridge I have noticed the use of standard interlocking solid concrete traffic protection blocks on the side of the roadway and presume that these are going to remain for some time.
I recall that this bridge was designed with an aerodynamic deck section and the requirement for an open deck has prevented the installation of solid barriers or wind deflection structures, as are present on the newer M4 Bridge.
Presumably the installation of a long length of these concrete blocks will alter the pattern of eddy shedding during a lateral wind and also alter the dynamic response of the bridge to the lateral forces.
Since these blocks may well be in place during the coming equinoctial gales, I would be interested to know whether the necessary aerodynamic and structural calculations have been carried out to check on the stability of the bridge with this modified profile.
KG Eickhoff (M), 3 Gilbert Road, Hale, Altrincham, Cheshire, WA15 9NR