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Neptune's Staircase, Caledonian Canal
Banavie, Scottish Highlands, Scotland, UK
Neptune's Staircase, Caledonian Canal
associated engineer
Thomas Telford
William Jessop
Mott MacDonald
date  1808 - January 1811
UK era  Georgian  |  category  Locks  |  reference  NN113769
ICE reference number  HEW 84/07
photo  © and licensed for reuse under this
Neptune's Staircase, also known as Banavie Locks, is a flight of eight locks on the Caledonian Canal — and possibly the canal's most famous feature. At the time of its completion, it was the longest length of masonry on any canal. The locks remain in use.
The Caledonian Canal links the Irish Sea with the North Sea via Scotland's Great Glen. The whole canal opened in 1822. Thomas Telford (1757-1834) was its principal engineer, with William Jessop (1745-1814) as consulting engineer. Neptune's Staircase is at the south western end of the canal, about 2.4km from where it joins Loch Eil and Loch Linnhe.
Telford forecast that construction would take four years. However, the locks were completed early and the speed of construction, and possible management shortcomings, were to result in structural problems in later years.
The eight locks are each some 55m long, 12.2m wide and approximately 6m deep, and can accommodate vessels up to 45m long and 10.6m wide. Together the flight forms a stretch of solid masonry 457m long, which raises the canal 19.5m from its level at Corpach Moss (south western end) to the Gairlochy reach (north eastern end).
Robert Southey (1774-1843), Poet Laureate from 1813, visited the locks with Telford and described the flight as "the greatest work of art in Britain".
There were local collapses of the lock walls in 1829 and 1839. In 1844, all the gate recess walls had to be rebuilt. The original lock gates were replaced by new ones made from oak and steel in 1890-1906.
Passage through the flight of locks is slow, as vessels have to await the completion of the passage of any vessel coming in the opposite direction. In 1845, construction of a passing place midway was considered but was found to be impractical and too expensive. Originally, 12 lock keepers were required to work the hand-operated lock gates using capstans. Since mechanisation in 1968 — when the gates were converted to hydraulic operation — only two keepers are necessary and it takes about 90 minutes to pass through all eight locks.
In 1929, a serious accident occurred. A vessel crashed through the gates of the top lock and was swept into the lock below. The sudden emptying of the locks caused the masonry walls to bulge and they had to be rebuilt. The gates of the two locks also collapsed and had to be replaced, though a greater catastrophe would have ensued had the third lock's gates given way. The canal was closed for three months during repair work.
In 1998-9, during the winter closure of the canal, the lock walls were stabilised and the gates were replaced. Each gates weighs some 22 tonnes. Consultant Mott MacDonald designed new walkways across each of the lock gates and supplied the detailed hydraulic designs for the bypass system — to allow water levels in the lower reaches of the canal to be maintained while the locks are out of commission.
The canal is maintained by British Waterways and is now open year round. A new lighting system was installed at Neptune's Staircase in recent years. It is bathed in green light at night.
Resident engineer: Alexander Easton
Main contractor: John Simpson, John Wilson
Research: ECPK
reference sources   CEH SHI

Neptune's Staircase, Caledonian Canal