The Canal History
The Rochdale Canal was completed in 1804 and is one of three canals that cross the Pennine hills. This is the only one that doesn’t use tunnels. In addition it was a broad canal with bridges and locks that allowed boats of 14 feet width to pass through.
The one downside of not using tunnels is that it originally had 92 locks. These days two of them have been combined into one deep lock.
Competition from railways and roads subsequently led to a decline in goods being carried and by 1937 the only section left in operation was at the Manchester end of the canal.
In 1965 there was talk of abandoning the canal but by this time leisure boating had become very popular in the UK and there was a campaign to keep it open. Work was started and the canal slowly re-opened in a number of different stages. The whole length finally reopened in September 2007.
Details of this lock
This lock is also known as Blue Pits Middle Lock. It is the middle of three locks named after a nearby quarry that used to produce a type of blue clay. Built across the the end of the lower gate is a stone arch bridge. As well as giving access to both sides of the lock to operate the gates it also carries the tow path from one side of the canal to the other. A lock always forms the narrowest part of the canal and so incorporating the bridge into the lock makes it smaller and cheaper to build.
Canal tow paths are usually built on one side of the canal to cut costs. Occasionally the tow path switches from one side of the canal to other and the bridge carrying the tow path to the other side is known as a changeline bridge.
On many locks there are warning signs about making sure the boat does not get caught on the cill.
It's not always obvious what this means, but basically the wooden lock gate does not go to the bottom of the lock but sits on a stone base. When the lock is full and a boat is going down, the cill is not visible. This means that when the water is released from the lock it is possible for the boat to get caught on the cill.
This lock was at its lowest when I took the pictures and the cill is clearly visible. When the cill is visible it's much easier to understand the hidden danger.
It can also be seen on the pictures that the gates nearest the bridge had been left open.
This lock was renovated in 2002 as part of the regeneration works and new lower gates were installed.
This
website shows the renovation works.
This lock was made a Grade II listed building by English Heritage in 1985 before the canal was restored.
link
The web site states that the lock's engineer was William Jessop and that the lower gates were missing. These were the gates shown on the renovation website. It also tells us that the parapet walls of the bridge, which appear to be largely rebuilt, has a segmental arch.