26m tunnels have been dug by hand, for a Scottish Water flood prevention scheme in Greenock.
Amey Black and Veatch (ABV), who are delivering the project on behalf of Scottish Water, called in Northern Tunnelling to hand-dig tunnels totalling 26m in length.
Engineers tunnelled under the roadway from a section of the car park on Inverkip Street in Greenock and then across to a roundabout.
In both cases, difficult ground conditions meant the more modern method of tunnelling with a guided tunnelling machine wasn’t possible.
ABV project manager Scott Henry said: “The hard, rocky ground meant that we had no alternative but to return to traditional methods and use hand operated tools like picks and shovels to do the excavations.
“It was really hard work for the tunnellers. They’ve removed approximately 115t of debris comprising mainly of reinforced concrete, brickwork foundations, sandstone and whinstone rock.”
ABV communications manager Paul Milligan added: “We’d like to thank Paul Bonthron, a site agent from Northern Tunnelling who has supplied us with some fantastic shots of the tunnelling on this project. With the work taking place underground and out of sight, his photographs really do help illustrate the full extent of what’s been carried out here.”