Engineers will spend three days underground inching their way through the dark to carry out the important inspection. High powered lighting will be bought in to illuminate the tunnel roof so that any cracks or deterioration can be identified and repair works planned.
Standedge Tunnel took 17 years to dig and was finally completed in 1811. It cost the lives of 50 men and more than £123,000 – the equivalent of £8.8 million in today's money. Having fallen into decline due to competition from the railways, the last commercial boat passed through the Tunnel on 13 October 1916, before an ambitious restoration, dubbed the ‘impossible restoration', saw it reopen in 2001.
Legging through the tunnel
With no towpath, the horse drawn canal boats originally had to be unhitched and ‘legged' the length of the tunnel. This required men to lie on their backs on top of the boat and ‘walk' along the tunnel roof, moving the boat along with them. Legging was a challenging and often dangerous job and professional ‘leggers' were employed to propel laden freight barges through the tunnel. In its heyday the tunnel operated 24 hours a day and ‘legging' took about 3 hours. Today the tunnel is hugely popular with boaters coming from across the world to make the epic journey across the Pennines from Yorkshire to Lancashire.
Chris Reynard, principal surveyor at the Trust said: "Standedge Tunnel is an amazing engineering achievement, especially considering it was dug by hand 200 years ago by navvies armed only with picks, shovels and dynamite.
"It's strange to think that almost exactly 100 years ago the tunnel was shut down to commercial boats and its restoration described as "impossible". Fifteen years after it was reopened it is more popular than ever with boaters and tourists, which is why it's vital that we carry out this annual check-up."
For more information, visit Standedge Tunnel