Gas Street Stop Lock

[Derek R.]

If you approach the narrows in Gas st fully loaded at fair speed and then shut off it floods the cafe tables on the lockside......... honest

 

Much fun! Many bridge'oles will do likewise, there's one below sewerage lock on the GU - bridge 145, nasty bend where the offside arch will catch the cabin side if you don't keep towpath side, and the path is low under the bridge. No end of times folk stand under the bridge to watch the boat go by and get very wet feet.

[Pluto]

I believe that the stop lock on the Birmingham & Warwick Junction was indeed a slight fall. It is difficult for it to be any other way. Yet having picked up on an alternative, thought I would check opinion. Many thanks for the comments.

 

It is also interesting to see when more than a standard set/ pair of stop gates apply. On the Stratford Canal at Kings Norton the lock gates were originally a pair of mitered gates at each end of the lock only to be replaced by that special arrangement once the lock was narrowed to a guillotine gate at each end. Thinking about other canal junctions, I wonder how the arrangement at Leigh between Leeda & Liverpool and Bridgewater was made?

 

Ray Shill

I think that the agreement for building the Leigh branch required all water to be passed to the Bridgewater. There must have been some sort of gate there originally, but now just a stop plank crane, typical of the Bridgewater. However, under the 1907 (IIRC) Bridgewater Act, they ensured protection of the Bridgewater from subsidence, or at least getting payment from the coal owners, whilst on the L&LC, coal owners were allowed to remove coal from under the canal following the 1891 or 1892 Acts without compensating the canal. As part of the correspondence between the two canals regarding the 1907 Bill, there is a sketch of a lock at Leigh with gates pointing in both directions. Presumably, they could not control exactly how subsidence would affect each canal and were hedging their bets on future canal levels. I don't think the lock was built, but subsidence between Worsley and Wigan has dramatically affected canal structures, with subsidence of easily 1 foot a year when mining the seams under the canal.

[magpie patrick]

I think that the agreement for building the Leigh branch required all water to be passed to the Bridgewater. There must have been some sort of gate there originally, but now just a stop plank crane, typical of the Bridgewater. However, under the 1907 (IIRC) Bridgewater Act, they ensured protection of the Bridgewater from subsidence, or at least getting payment from the coal owners, whilst on the L&LC, coal owners were allowed to remove coal from under the canal following the 1891 or 1892 Acts without compensating the canal. As part of the correspondence between the two canals regarding the 1907 Bill, there is a sketch of a lock at Leigh with gates pointing in both directions. Presumably, they could not control exactly how subsidence would affect each canal and were hedging their bets on future canal levels. I don't think the lock was built, but subsidence between Worsley and Wigan has dramatically affected canal structures, with subsidence of easily 1 foot a year when mining the seams under the canal.

 

You are correct with the 1907 Act, although it contains no details of control structures. I spent about two years on and off , along with a colleague, advising the Coal Authority on their obligations under this act.

 

The "mining length" as it is called runs from south of Worsley to the junction with the L and L; the proprietors of the mines passed the act to allow them to take coal from under the canal by making themselves liable for any maintenance that resulted from subsidence. As a piece of legislation it is unique, and the Coal Authority are still bound by its terms some 100 years later.

 

The rate of subsidence is very complex, and I will admit I don't fully understand it. It depends on the depth of the seam as well as the size of the seam, so for example a six feet seam 20 feet down will cause more subsidence than a seam the same size 200 feet down. The subsidence is also curved, so at the edge of the mining there is very little settlement but in the middle there is a lot. One only has to stand on the embankments of the Bridgwater Canal to see this. These embankments are where the canal was built at ground level, and some are 30 to 40 feet high.

 

Of course, when the mining act was passed, the leeds and liverpool had locks a lot closer to the junction with the Bridgwater, at Dover and Plank Lane. Those locks migrated upstream to Poolstock because of subsidence

[Pluto]

 

Of course, when the mining act was passed, the leeds and liverpool had locks a lot closer to the junction with the Bridgwater, at Dover and Plank Lane. Those locks migrated upstream to Poolstock because of subsidence

By 1905, there was already one lock at Poolstock, with the level of the canal five feet lower below the lock. Further towards Leigh, in places the canal became four feet lower between 1893 and 1906, so the total subsidence was around ten feet. The second lock at Poolstock was erected in 1913. Pagefield, on the way to Liverpool, replaced Crook Lock in 1913. On the L&LC, it was the Winterburn Reservoir Act which brought about a change in attitudes to mining, with the canal company paying for the effects of subsidence after the Act, rather than the collieries. It was not part of the Act, more a gentlemen's agreement, no doubt the canal making a good return on the coal trade. The lock suggested at Leigh would have been like this:

 

[Heartland]

Subsidence, of course, is another reason for lock gates. The plan provided by Pluto, provides a useful insight into what might have been.

 

Ray Shill