Case Study 11

Refurbishing an underwater tunnel

December 19, 2017

tunnel

The Queensway Tunnel is a road tunnel under the River Mersey, in the north west of England, between Liverpool and Birkenhead. When construction was completed in 1934, it was the longest underwater tunnel in the world at 3.24 kilometres.

In 2011, after 77 years of service, an 11-month refurbishment of the tunnel began.
The old plastic corrugated protective wall cladding was replaced with ceramic steel, chosen for its durability, strength and low maintenance. It’s easy to clean as well as giving the tunnel a 21st century look.
The new cladding system also enhanced safety, improving light reflection and increasing brightness by 14%. This reduces energy consumption and extends the lightbulb life from seven to eight years, saving money, and reducing the carbon footprint.

The cladding panels are supported by a lightweight modular stainless steel framework of cold formed members, manufactured from 390 tonnes of stainless steel strip. Type 304 (UNS S30400) nickel-containing stainless steel was chosen for the framework because of the aggressive environment inside road tunnels.
A strict cleaning schedule was defined to prevent the accumulation of dirt and contaminants such as chlorides or sulfates which might lead to localised corrosion.

The stainless steel framework was designed to be as lightweight as possible, to both reduce material costs and facilitate quick installation, enabling the refurbishment to be completed with minimal disruption to the normal running of the tunnel. The framework system also needed to be easily demountable and panels replaceable in the event of any damage, for example by vehicle impact.
Designed on a modular basis, each sub-frame supports one cladding panel.

The innovative design concept of pre-fixing sturdy top and bottom rails to the tunnel wall and then fastening the stainless steel frames in position reduced installation time considerably. This process also minimised disruption to tunnel users.

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December 19, 2017

cover

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