In the late 1940s, MHA designed road, pedestrian and cycle tunnels under the River Tyne (Tyne Tunnel) though the road tunnel was not built until the 1960s. Further commissions for road tunnels were received for the revitalised Dartford tunnel in 1956, Mersey Kingsway tunnel in 1966, Blackwall southbound tunnel in 1967, second Dartford tunnel in 1972, and the Hatfield, Bell Common, Holmesdale and Penmaenbach tunnels in the 1980s. In all, MHA were involved in the construction of all but five of the UK's longest road tunnels (the exceptions being the Heathrow Cargo Tunnel, Heathrow Main Tunnel, Clyde Tunnel, Limehouse Link tunnel and Rotherhithe Tunnel).