Costain is working with Transport for London to renew the Gallows Corner Flyover, a strategic link that joins the A127 to the A12 and enables access to the M25.
The flyover was built in the 1970s as a temporary structure and is now in urgent need of renewal. The strengthened flyover will allow for the removal of speed and weight restrictions, improving journey times, reliability and safety on London’s road network.
Costain previously completed the detailed design for the refurbishment of the complex structure, where we identified 11% of carbon savings in the concept design, which is equivalent to 644 TCO2e. The concept design also gave a 35% reduction in carbon compared with demolishing the structure and rebuilding it.
To deliver the upgrade, Costain applied a design for manufacture and assembly (DfMA) approach which saw parts of the new structure manufactured offsite and then transported to the location. This minimised disruption from onsite working and reduced the use of carbon-intensive materials. TfL and Costain also implemented extensive public communication and engagement ahead of the closure of the flyover to support local residents with their journeys and planning.
An important milestone in the project has been the removal of the old flyover structure, which weighed more than 1,150 tonnes and required 36 complex lifts. The removal was also achieved whilst managing the switch of a bus lane from the west side of the roundabout to the east, with no disruption to the bus network.
Costain has subsequently dismantled sections of the old flyover offsite to reduce the environmental impact and minimise noise disruption for residents.
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