A downtown bridge located in West London, the Hammersmith Flyover is one of the first prefabricated structures built using post-tensioned concrete and connects downtown London with Heathrow Airport and western England. Comprising 16 spans and measuring 626 m (2,052 ft) in length (863 m or 2,831 ft with its two ramps), the bridge carries the express lane of the A4 highway as it crosses over the Hammersmith roundabout.
A bridge under constant supervision
Built in 1961, the bridge presented an innovative structure for its time. However, wear and tear has taken its toll over the years, especially as a result of water damage. Inspections by the Highways Agency in the early 2000s revealed corrosion in the post-tension cables supporting the prefabricated concrete structure. For that reason, Transport for London (TfL) decided to put in place one of the largest structural monitoring programs in Europe, installing more than 400 acoustic sensors. The monitoring quickly indicated a higher rate of wire breaks than other similar programs in the United Kingdom. A new inspection at the end of 2011 confirmed the structure’s deterioration, leading to its emergency closure to complete a first round of renovation work ahead of the London Olympics, scheduled to begin six months later. A second renovation phase was also planned for 2013.