Tunnels
The construction of tunnels was one of the most difficult tasks facing canal engineers – hence many early canals followed Brindley’s contour method and wound their way around hills.
Unfortunately this was not seen as a sensible long term solution as the winding, uphill course increased journey times and the extra locks soon led to water shortages at higher levels.
Tunnels were traditionally built by plotting out the route across the hilltop and then sinking down several shafts. Miners would then begin digging in both directions from the bottom of the shafts – and from the tunnel entrances. The idea was of course, that they would meet in one perfectly straight line. Unfortunately this did not always happen and some canal tunnels have obvious kinks in them.
Blisworth Tunnel, in Northamptonshire, is one of the longest in Britain. 3076 yards long and broad enough for two narrowboats to pass, it is surpassed only by Standedge Tunnel (on the Huddersfield Narrow Canal) and Dudley Tunnel in the Black Country near Birmingham.
Building Blisworth Tunnel, was the most troublesome part of the Grand Junction Canal's (now known as the Grand Union Canal) construction. When work began, in 1793, the building of a 3km tunnel was a major feat of engineering with no mechanical aids beyond the basic picks, shovels and wheelbarrows available. To add to their basic problems, just three years into the project the navvies hit quicksand. All work had to be abandoned and a new course begun.
The longest, deepest, and highest canal tunnel in the country is Standedge Tunnel on the Huddersfield Narrow Canal. The tunnel took 16 years to build at considerable cost of life - with the final section being overseen by renowned engineer Thomas Telford in 1811. The tunnel is 196 metres (645 feet) above sea level, runs for just under three and a half miles and burrows 194 metres (638 feet) underneath the Pennines.
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