| With the recent completion of the Tamar Bridge strengthening and widening project, the UK-based company Bridon has celebrated a 40 year relationship with this bridge, spanning back to 1962 when the bridge was first constructed. The Tamar Bridge was the first modern suspension bridge in the UK. At just over a third of a mile in length, with a 1,100ft main span, it was at the time of construction, the longest suspension bridge in the UK. Its 6,000 tonnes of structural steel and concrete deck were suspended from 15� diameter main cables. Since its 1962 opening, the significance of the structure to the South West economy has been demonstrated by the increased traffic passing through its 250ft towers.
The expertise of Bridon�s Structural Systems team was again brought in to help with additional strengthening of the Tamar Bridge which is situated on the A38 between Devon and Cornwall. This is now completed following an official opening by HRH the Princess Royal. Bridon supplied 102mm and 110mm � prestressed galvanised locked coil cables, fitted with a combination of block and threaded cylindrical sockets, amounting to some 220 tonnes of cable. Bridon's cables were installed from the winter of 1999 onwards, and the company worked closely with main contractors Cleveland Bridge UK Ltd, advising on cable design, specification and installation. All cables were protected with Bridon's innovative Metalcoat cable corrosion protection system. The first phase in connection with the strengthening and widening programme comprised of installing 12 lengths of 102mm � locked coil cable, each length with a breaking load of 1,031 tonnes. These provide extra support for the existing main cables. Following this, along the Bridge�s centre span, six lengths of 110mm � locked coil cable, each with a breaking load of 1,244 tonnes were fitted. In addition to the socketed cables, Bridon also designed and supplied the equipment for jacking and tensioning the cables.
�Bridon supplied the original bridge suspension system, comprising of 60mm diameter locked coil main cables and hanger cables in 1962. The original cables are still performing to specification, however the higher loadings caused by increased traffic flow and new legislation allowing heavier vehicles, required additional cables to be fitted as part of the recent strengthening and widening project�, commented Mr Barrie Mordue of Bridon. Nowadays, up to 40,000 vehicles use the crossing daily. Strengthening was needed to contend with this, and also to cope with vehicles of up to 40 tonnes. In addition, the bridge was widened. Two new lanes were added to maintain traffic flow during construction. These additional lanes remained after completion - one for local traffic and another for pedestrians and cyclists. The bridge remained open throughout the three year construction programme.
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