Text and photographs copyright of Jim Shead.
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This article Staircase Locks is the copyright of Jim Shead - A look at staircase locks. First published in Waterways World May 1998
After operating a few dozen locks most boaters feel thoroughly at home with the procedure but an encounter with staircase locks can give pause for thought to even the experienced crew. A lock staircase, or riser, is defined as two, or more, adjacent locks where the upper gates of one lock serve as the lower gates of the next. This means that there are no pounds between locks and on leaving one lock the next lock in the staircase is entered immediately. The method of operating staircase locks is somewhat different from that used for single locks and the variety of lock designs do not aid our understanding, you may be familiar with the Leeds and Liverpool staircase locks but that may not be of much help when going through Foxton locks.
As you might expect the staircase lock was a later development than the single pound locks, of the type that are usual on our waterways, but lock staircases had been in use for over a hundred years before the Bridgewater Canal was built, at the start of Britain's canal age. In France in 1642 the Briare Canal was opened and had 40 locks, including a staircase of 6 locks rising 65 feet. What is more surprising is that England also had a staircase lock that pre-dated the Duke of Bridgewater's Canal, this was the Old Double Lock on the Sankey Brook Navigation opened in 1757. The popularity of the design continued throughout the canal age, other early examples being Botterham Locks on the Staffordshire & Worcestershire Canal (1772) and the many Leeds and Liverpool staircases which date from about 1777. Staircases were also common in South Wales, on the Glamorganshire there were 2 lock staircases and a 3 lock rise at Nantgraw.
You will see from the table giving examples of staircase locks that there are many that are navigable and some that are not. Some of those on the Chesterfield Canal are currently being restored (see WW December 1995), as are Ryeford Double Locks on the Stroudwater, others can only be seen in a derelict state or have disappeared completely. Through the years many staircases have come and gone, Snakeholme locks on the Driffield Navigation were originally single locks, were changed to a staircase in 1776 and are now unusable. Before 1841 the Caldon branch of the Trent & Mersey Canal had a three lock staircase at Hazelhurst, then the course of the canal was changed so that the main line went under the Leek branch, as it does today, and three new separate locks were built on the new section of canal. At Chester the Northgate staircase was changed from 5 to 3 locks in 1797. The beginning of the nineteenth century saw the building of some of the most impressive lock staircases, the largest being at Banavie on the Caledonian Canal with eight locks each 150 feet by 35 feet. The canal also has two other staircases, at Muirtown and Fort Augustus. At the same time as these locks were being built the narrow staircases at Foxton and Watford on the Grand Union Leicestershire Section were under construction. William Jessop and Thomas Telford, the engineers of the Caledonian Canal, were able to make full use of staircase locks as they had a plentiful supply of water, this was not the case on the Grand Union and side ponds were provided to reduce water use at the Foxton and Watford staircases.
The building of staircase locks did not end with the nineteenth century, the newest must surely be the two wide locks at Bascote. They were built in the 1930s to replace two single narrow locks as part of the Grand Union Canal Company's modernisation scheme.
When you are travelling through a staircase you need to think where the water is coming from or going to. For example you arrive at the bottom of a three lock staircase just as a boat, coming the other way, has left the bottom lock. At single locks this is good news, you can go in and fill up the lock, but with a staircase the top two locks will also be empty so there is no water to fill the bottom lock. You must fill the top two locks before filling the bottom lock otherwise you will not have enough water to take you to the top. This helps to explain why staircases need more water, we need two locks full of water to get to the top where one lock-full from the summit level would suffice on flight composed of single locks, no matter how long the flight. If the staircase had four or five locks there would be three or four locks to be filled using even more water. If you follow another boat up the staircase all the locks are full, you can just empty the bottom lock, enter and fill each lock as you progress up the flight. This is easier and uses only one lock of water instead of two.
If you are going down a staircase flight think where the water you empty from the lock will go. Some locks, like the narrow locks in Stourport basins, have a generous overflow weir running the whole length of the lock so it is possible to empty the top lock even though the bottom one is full. At some other locks such an attempt would leave bystanders on the lower lock side with very wet feet. On the Leeds & Liverpool, for example, the recommended procedure is to empty the lower locks before descending the staircase. This is easy on a double lock as the bottom one will only empty to the level of the canal below the locks, however, with three or more locks it is possible to run locks dry, which, in this case, is not what is meant by the word 'empty'. To help overcome this problem British Waterways provide level markers inside the locks so that you do not over empty them.
Taking turns at single locks is straight forward. If the lock is in your favour, i.e. empty when going up hill or full when going down hill, you go in and anyone coming in the opposite direction waits. This is the quickest, simplest mode of operation and the most economical use of water. With staircase locks the situation is reversed, it is quicker, simpler and uses less water if you immediately follow someone going in the same direction rather than wait for someone to come through from the opposite direction. Lock keepers and instruction notices encourage the passage of several boats in the same direction before passage in the other direction is started. This obviously speeds the process through narrow flights as several boats can be progressing through the flight in the same direction. In wide staircase locks it is possible for single narrowboats to pass each other, or for a single narrowboat to pass a pair coming from the opposite direction, although the latter case does require a couple of sideways shuffles in the locks.
At the larger staircases (e.g. Bingley, Foxton and Watford) there are lock keepers on duty to give help and advice, and to control the movement of boats through the locks. At some unmanned staircase locks there are instruction boards. At Foxton and Watford there are side paddles (painted red) to control the water into and out of the side ponds, installed as a water saving measure. The procedure is to open the red paddles before opening the normal ground paddles. This not only saves water but simplifies the working of the locks as it is not necessary to fill or empty locks in preparation, the side ponds take or provide water as required.
On the Staffordshire and Worcestershire Canal at Bratch there are three locks that are unique on our waterways, not a staircase - each lock has its own top and bottom gates - but three locks with incredibly short pounds between, no more than a few feet long. These intermediate pounds have been extended by culverts under the towpath that link them to side ponds. In this way these seemingly tiny pounds can supply enough water to operate the locks in the normal manner. Less than two miles away at Botterham on the same canal is a conventional two rise staircase. Why Bratch was built this way must remain a matter for speculation but water usage no doubt played a part in the decision. Perhaps if they had been built thirty or forty years later the canal engineer would have used a staircase with side ponds like those at Foxton.
Staircase locks provide interest for the boater, historian or towpath walker. Many feature in our best known waterway views; Fort Augustus on the Caledonian, Bingley Five Rise on the Leeds & Liverpool, and Foxton on the Grand Union all present impressive sights rising steeply up hillsides, but there are plenty more to be found, perhaps not all so spectacular but each with its own charm and interest.
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