When you drive through the two Mersey tunnels, the 1934 Queensway and the 1971 Kingsway, you’re being watched – and cared for – by a small team of professionals, many cameras and, in Queensway, a great deal of 1930s over-engineering.
The Mersey Tunnel Tour is the public’s opportunity to see behind the scenes of Queensway, and to understand that it’s much more than a hole in the ground.
The tour takes visitors from the top of the George’s Dock Building, which is essentially an elegant Art Deco fan-assisted chimney with an office block attached, to the safety refuges below the road-deck. And, of course, back to the surface.
It’s a moderately strenuous two hours, and because the ventilation station is a dusty, though not dirty working building, it’s a good idea to go dressed for gardening rather than tourism. (On the 2011 Liverpool’s Heritage tour, we came straight from St George’s Hall and may have been a little over-dressed.)
The 1920s designers couldn’t be sure how the finished tunnel would work practically. At the time it was the longest under-river bore in the world. Furthermore, traffic was changing as horse-drawn carts and electric trams began to give way to motor vehicles.
In these circumstances, especially in a two-way tunnel, ventilation was crucial, and could not be skimped. The later Kingsway is in fact two unidirectional bores, so the traffic itself acts as a piston, pushing foul air through. Queensway has six ventilation stations; Kingsway needs only two. In each case, the fresh air has to be pumped in at either end: after all, there’s a river in the middle.
The party-piece on the tour is to see one of the 22ft-diameter fans start up, high in the George’s Dock building. These are the original 1934 fans, built into the building. Even at the lowest of four speed-settings, they’re distinctly draughty.
And they work. When you stand beside the traffic lanes below the river, the air is remarkably fresh.
Another resonant experience is to stand below the road-deck on Central Avenue, an empty corridor intended for double-deck electric trams to connect the Liverpool and Birkenhead systems.
The original specification assumed that the road tunnels would carry 3,000 vehicles per hour, travelling at an average speed of 15mph while maintaining a distance of 100ft apart in four lanes. Down below, an endless procession of double-deck trams, each carrying perhaps sixty people, could have shifted many more thousands.
Of course, it didn’t work out that way.
In a different age of faster, cleaner road vehicles with far better brakes than between the Wars the ventilation system has a much easier time, yet carries enough capacity to cope with any foreseeable emergency such as a blockage or fire.
One of the benefits of the Mersey Tunnel Tour is the reassurance of seeing how efficiently motorists are looked after if the traffic in the tunnel stops in its tracks.
Not that most people give an emergency a second thought as they breeze between Liverpool and the Wirral, listening to their car radios. And not realising why they can use their radio in the tunnel.
Booking a Mersey Tunnel tour requires premeditation: e-mail to firstname.lastname@example.org.
For further background information on the Queensway Tunnel, see http://www.cbrd.co.uk/indepth/queenswaytunnel.