Sapperton Canal Tunnel

 invisible, canal tunnel

 Upload a photo

When Sapperton tunnel opened on 20th April 1789 after five years of construction it was the longest tunnel built in England, at 3,817yds (2·17 miles or 3·49 km), and its bore of 15ft was considerably larger than any other tunnel that had hitherto been constructed.

It was certainly one of the (albeit almost forgotten!) great engineering achievements of the age, preceding Brunel's more famous Box tunnel by 52 years and exceeding its length by 500 yards.

The method of construction was to mark out the line of the tunnel on the surface and sink 24 shafts. These were then linked up creating a headway which could then be opened out to the full bore. Some of the spoil heaps in Cirencester Park were landscaped to avoid offending Earl Bathurst, and appear as circular clumps of trees today.

Just over half of the tunnel is in rock and in many places this was solid enough not to require any lining but fissures in the rock made keeping the canal watertight a challenge. Where the rock was less solid, the tunnel was lined in brick or stone.