Sapperton canal tunnel
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The Coates Portal at the south-eastern end of the Sapperton Canal Tunnel
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| Overview | |
|---|---|
| Location | Sapperton, Gloucestershire |
| Coordinates | 51°42′58″N 2°04′00″W / 51.7162°N 2.0666°WCoordinates: 51°42′58″N 2°04′00″W / 51.7162°N 2.0666°W |
| OS grid reference | SO955019 |
| Status | disused |
| Waterway | Thames and Severn Canal |
| Start | 51°43′43″N 2°04′58″W / 51.7287°N 2.0828°W |
| End | 51°42′15″N 2°03′01″W / 51.7041°N 2.0504°W |
| Operation | |
| Opened | 20 April 1789 |
| Closed | c. 1910 |
| Technical | |
| Length | 3,817 yards (3,490 m) |
| Towpath | No |
The Sapperton Canal Tunnel is a tunnel on the Thames and Severn Canal near Cirencester in Gloucestershire, England. With a length of 3,817 yards it was the longest canal tunnel, and the longest tunnel of any kind, in England from 1789 to 1811.
Although the Thames and Severn Canal was authorised by an Act of Parliament on 17 April 1783, the details of the tunnel had not been worked out, and arguments about its size continued for two or three months. Boats on the Severn were trows and were 15 feet (4.6 m) wide, while those on the Thames were Thames barges, which were 12 feet (3.7 m) wide. The only long tunnel in the country at the time was Harecastle Tunnel, which was suitable for narrow boats just 7 feet (2.1 m) wide. A party of Commissioners from the Thames thought that the cost of a wide tunnel would be prohibitive, and that it should be built for narrow-beam boats, with the trows or barges unloading their cargos at each end of the tunnel.
By late summer, the decision had been taken to build a broad tunnel, 15 feet (4.6 m) high and 15 feet (4.6 m) wide, and the company advertised for tunnellers in September. The tunnel would be 3,817 yards (3,490 m) long, and was expected to take four years to complete, beginning in early 1784. In order to speed the work, 25 shafts were sunk along its length, to provide multiple workfaces, the deepest of which was 244 feet (74 m). The construction contract was awarded to Charles Jones, who managed to build about one third of it, but then had financial difficulties, and so a number of other contractors were engaged to work on smaller sections of it.
The tunnel was opened on 20 April 1789 after five years of construction. It has no towpath; boats were propelled through the tunnel by legging. There were some defects in the workmanship, as it had to be closed for ten weeks after only a year, while repairs were carried out.
It was superseded as the longest canal tunnel in England in 1811 by the Huddersfield Narrow Canal's Standedge Tunnel, which was 5,456 yards (4,989 m) long when built, later extended to 5,698 yards (5,210 m) to accommodate the adjacent railway tunnel, and remains the highest, longest and deepest canal tunnel in Britain - though, unlike Sapperton, Standedge can only accommodate 7-foot-wide narrowboats (2.1 m). Strood Tunnel on the Thames and Medway Canal was also longer at 3,946 yards (3,608 m) when it opened in 1824, but was cut in two in 1830 by opening out a short section to create a passing basin.
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