The Hammersmith Flyover forms part of the A4 route connecting London to Heathrow Airport. This was the first bridge in the UK to be constructed using precast concrete sections. These sections were compressed together by pre-stressed steel cables which ran internally through the bridge. After corrosion had been detected on the steel cables Transport for London conducted a detailed 2-year monitoring inspection of the internal cables to assess the level and speed of the corrosion. After the inspection was completed it was agreed that a £100m strengthening programme would be required to repair the bridge and ensure its longevity for future generations.
Millar Callaghan were asked to fabricate the new internal cable strengthening support brackets. To ensure that the support brackets distributed the load form the cables evenly through the structure, each guide tube on the brackets would be rolled to an exact radius for each location. It would then be off set to a specific angle and to avoid damage to the cable due to expansion and contraction, the liner tube ends would be flared away from the cable. All fabrication work had to be carried out to a maximum tolerance of less than 0.5mm.
On completion of the contract Millar Callaghan’s quality department supplied the client with a complete quality package. This quality package ensured the client that all of the steelwork complied with new CE regulations and that it had been manufactured and certified to execution class 3.
