I visited the Kingsway Tunnel, which first opened in 1971. Wallasey was chosen as the location for the second Mersey Tunnel because it is a point where the Mersey river narrows enough to build a tunnel.
There is also a tunnel underneath the Mersey Tunnel – called Central Avenue, it was originally intended to be used as a tramway but was never operational.
The Mersey Tunnels have their own police force, the Mersey Tunnels Police. The Mersey Tunnel Scheme which helps traffic control was claimed to be the largest CCTV system for traffic management outside of North America.
I also saw the old control room and the new control room which was only opened three years ago – you can see all the screens to help keep traffic flowing through the tunnel.