THE Clyde Tunnel is a major artery through Glasgow now and a major technical achievement when it was built in the late 1950s.

Critical to its success was looking after its workforce as far as possible in difficult and dangerous conditions, with workers offered a decompression chamber, pictured above, to enter and leave the tunnel.

The miners tasked with digging three tunnels worked in a compressed air environment, meaning they had to go through the process to avoid crippling decompression sickness "the bends".

Using the chamber added an hour to their working day and some refused. Two men died.

The tunnel linking Govan and Whiteinch was expected to be used by 9,000 vehicles daily when it opened in 1963. It now caters for 65,000 cars and lorries. It cost £10million, £200m in today's prices.

Built to offer another way across the river when it was impossible to build a bridge due to river traffic, by the time it opened, shipping had moved to the Firth of Clyde.

Still, many drivers trying to get around the city today have reason to be grateful for it - and the men who built it.