The Clyde Tunnel is a crossing beneath the River Clyde in Glasgow, Scotland for road traffic, cyclists and pedestrians. Two parallel tunnel tubes connect the districts of Whiteinch to the north and Govan to the south in the west of the city. History Efforts to improve the transport infrastructure of Glasgow post-World War II were hit by the problem of crossing the Clyde. Downstream of Jamaica Street in the city centre, it was perceived to be impossible to build a bridge due to the prevalence of shipping. The solution — to build a tunnel beneath the river — was not a new one, with the Harbour Tunnel at Finnieston having been built in the 1890s. However, the Clyde Tunnel project was to be built in the boom of the car era and would be a much larger project. It was given the green light in 1948 but financial difficulties prevented work from beginning until 1957. Construction A tunnelling shield, based on Marc Isambard Brunel's design used for the Thames Tunnel a century earlier, was used to dig the two tunnels. The tunnels were cut perfectly circular with the road deck sitting a third of the way up. Under each road deck is the pedestrian/cycle tunnel and ventilation ducts. 16 miners operated the shield working shifts in a compressed air environment to ensure that the rock and the river above did not collapse into the tunneling area. The digging itself would be done only with great difficulty due to the geology of the area, hard rock sitting under a soft silt layer beneath the river. The techniques for decompression after a period of working in a high pressure atmosphere had not been perfected at this time and – also owing to the prevalence of workers refusing to go through the decompression sequence given the length of time required (around an hour) – there were a number of cases of decompression sickness diagnosed as a result, resulting in two fatalities. Work on the tunnel was halted for a time after an explosion when compressed air escaped through the tunnel lining into the river, flushing outward in a fountain. The first completed tunnel tube, for northbound traffic, was eventually opened by Queen Elizabeth II on 3 July 1963, with the southbound tunnel opening in March 1964. The total cost of the project was £10 million. By this point, the migration of port facilities