Complex city-centre demolition
When Liverpool City Council’s inspection of two 50-year old flyovers found they were structurally unsound – the S Evans & Sons team was called on to plan a highly-complex and sensitive demolition within a busy city centre environment.
At 240 metres in length, each flyover consisted of ten spans which had been cast and post-tensioned in situ. Thanks to the team’s specialist expertise and careful planning, individual spans of the flyovers, each weighing 400-550 tonnes, were removed in a pre-determined sequence using various techniques with full consideration to the local surroundings.
Firstly, the adjoining footbridge was demolished using traditional techniques to pave the way for the removal of the main structure.
Twelve of the flyovers’ spans were removed by wire saw cutting in situ, supported by self-propelled modular transporter (SPMTs). Once free, the spans were transported at height to a jacking bay, before being carefully lowered onto a bespoke grillage system for further processing and eventual lifting in 40-70 tonne sections.
A bespoke temporary works scheme was designed and installed, which included propping to mitigate the risk
of premature collapse due to the unknown condition
of post tensioning within the structure.
A clamping system was also designed and installed on each supporting column to counteract the structures’ ability to move during the removal process.
Bridging three of the city centre’s busiest roads – Hunter Street, Byrom Street & Dale Street – special consideration was given to minimise disruption to motorists throughout, as well as to the wide array of neighbours, including Liverpool John Moore’s University, nearby galleries and Grade II listed building, the Liverpool World Museum. Major road closures and 24 hour working were put in place to meet the city’s needs.
As a result of Onsite Trail’s work, our engineers plotted an adapted method to safely demolish the remaining eight sections using mechanical methods over a weekend closure. This ensured that the residents of Liverpool could freely use the local road network without disruption during the busy month of December.
Materials from the flyovers have been recycled at a native site to be used on other city centre schemes.