Briefing: Queensway and Kingsway Tunnels, UK

When the 3·43 km long Queensway Tunnel under the River Mersey was built, it was described as an engineering feat without parallel. The cost was £8 million and, at the time, was said to be the biggest single municipal enterprise ever undertaken in Britain. In the summer of 2009, about 15 000 people took part in an ‘Under and Over the Mersey’ walkthrough to celebrate the 75th anniversary of the opening. Among them were two members of the original 1700 strong workforce who described their working conditions underground. About 1 200 000 t of rock and gravel were excavated during the building of Queensway Tunnel, much of which was later used to build the Otterspool Promenade on the banks of the River Mersey. Rock and gravel were replaced with 82 000 t of cast iron and 270 000 t of concrete. Working from both sides of the river, and despite what today might be considered primitive methods of excavation, when the two tunnels met mid-river there was a divergence of less than 25 mm.