Gas Street Stop Lock

[WJM]

Only a little question - when was the Gas Street Basin stop lock de-gated? I believe there was a six inch level difference. how was that resolved?

[magpie patrick]

Only a little question - when was the Gas Street Basin stop lock de-gated? I believe there was a six inch level difference. how was that resolved?

 

There was never a formal difference in level, although it did regulate flow between the canals their design level is the same. The gates were still there in the 70's I think, but were opened on nationalisation.

 

There was also a little swing bridge (well, swing plank) over it, but when the area was redeveloped this wasa not felt suitable for the general public and the present footbridge was built.

 

There is now a flow from the BCN to the W&B through the lock: a couple of years ago BW drained the lock for a week: when they took the stop planks out the lock was impassible for about half an hour because the flow through it was so strong.

 

There are a few stop locks that did have a change in level and have now been degated: Neachalls Shallow lock near Spaghetti Junction for example: the higher level has to be lowered rather than bringing the lower level up.

 

Now t

[PaulG]

The BCN Birmingham level was generally well supplied with water, the summit level of the B&W less so. The six inch difference in level may initially have been a "cunning plan" on behalf of the W&B to surreptitiously gain some water from the BCN. If so, it failed miserably, as in the early years of the B&W, the Worcester Bar prevented any water exchange at all between the two canals.

 

The Act of 1815 that authorised the building of the stop lock through the bar required the W&B to raise their water level by six inches to minimise water loss.

[Pluto]

The BCN Birmingham level was generally well supplied with water, the summit level of the B&W less so. The six inch difference in level may initially have been a "cunning plan" on behalf of the W&B to surreptitiously gain some water from the BCN. If so, it failed miserably, as in the early years of the B&W, the Worcester Bar prevented any water exchange at all between the two canals.

 

The Act of 1815 that authorised the building of the stop lock through the bar required the W&B to raise their water level by six inches to minimise water loss.

You can find lock gates, or their remains at many sites where two canal met, as canal companies were always jealous of their water supplies. Local to me are the junctions between the southern Lancaster and the L&LC. There are recesses for an extra pair of gates to block the canal just above the top gates at Wigan and above the top gates at Johnsons Hillock, the Lancaster Canal having built the flight.

The Lancaster used Jessop style locks which originally had an 'air hole' rather than a bywash. Excess water ran over a weir formed by a hole at the required water level above the top ground paddle and then through the paddle culvert into the chamber. The tops of the bottom gates were slightly higher than the tops of the upper gates, with excess water keeping the chamber full and running to waste over the top of the bottom gates. The system can be found on several canals, such as the Rochdale, where it was abandoned as the canal was extended through Lancashire in the early 1800s.

[WJM]

"There was never a formal difference in level,"

 

There surely must have been some difference in the levels. without one, the gates would have just flapped about uselessly!

[magpie patrick]

"There was never a formal difference in level,"

 

There surely must have been some difference in the levels. without one, the gates would have just flapped about uselessly!

 

Indeed they would! This is what actually happened on the Ashby Canal stop lock where the gates had to be bolted shut to stop them being blown open by the wind! This may also be why Kings Norton had guillotine gates

 

What I mean by "formal" is that the design water level of both canals, when they would be just on weir, was the same. If the lock had had no gates (as is the situation now) then any leakage in the W&B would simply have been topped up with BCN water, a scenario that displeased the BCN, so the lock had gates that were in all probability somehow held shut so that if the W&B leaked (as it does today, there is a net flow towards it) the level in the W&B would fall relative to the BCN and the W&B would have to find more water. I can't remember whether the stop lock had gates both ways, if it did then this would also work in reverse. This tempts me to have a look when I'm next in Birmingham (next Wednesday I think)

 

Stop locks are a subject in their own right, and the nuances are many and varied. the one at the entrance to the Somersetshire Coal Canal had three gates, two facing upstream into the SCCS, which was seven inches higher than the Kennet and Avon, and one facing the other way which would swing shut should the SCC suddenly empty follwoing a bank burst.

[alan_fincher]

This tempts me to have a look when I'm next in Birmingham (next Wednesday I think)

There's no evidence today that the gates were ever paired, one set for each direction.

 

Unless it's been heavily remodelled, there doesn't look to have ever been much room for that.

 

LATER EDIT:

 

I now accept the above is nonsense!

 

Views of the other end of the lock look very much like there were two gates at each end, one to close in each direction.

 

Edited November 17, 2008 by alan_fincher

[magpie patrick]

There's no evidence today that the gates were ever paired, one set for each direction.

 

Unless it's been heavily remodelled, there doesn't look to have ever been much room for that.

 

EDIT:

 

At least BW have not erected 3 square wooden oak 'stumps' alongside it!

 

 

Not so sure Alan: there look to be two opposing gate recesses at the far end of the lock and something "odd" just beyond the recess at this end...

 

I'll have a look, as I said. Meeting in the Axis next Wednesday.

 

(PS, anyone recommend an easy to use photo publishing site, the one I've been using is c**p)

[alan_fincher]

Not so sure Alan: there look to be two opposing gate recesses at the far end of the lock and something "odd" just beyond the recess at this end...

 

I'll have a look, as I said. Meeting in the Axis next Wednesday.

 

(PS, anyone recommend an easy to use photo publishing site, the one I've been using is c**p)

You are quite right of course.

 

I missed the two offset openings at the other end of the lock.

 

Not obvious from these pics how long they are, but definitely offset.

 

EDIT: No idea why this second shot has come up so dark - it didn't look dark before I uploaded it.

 

Edited November 17, 2008 by alan_fincher

[US Marines]

(PS, anyone recommend an easy to use photo publishing site, the one I've been using is c**p)

 

www.Flickr.com

 

I find it brilliant - and its HUGE - 4,000+ photos being uploaded every minute !

[Nine of Hearts]

There's a stop lock just down (or is it up?) from the Typhoo basin, and that one has all it's gates intact and well maintained (chained in the open position). I presume this is where the GU cedes to the BCN? Is this maintained for any reason does anyone know? The fact that there's a pair of gates at either end means that it can cope with a level difference in either direction. Don't remember seeing any paddles, however.

[RLWP]

There's a stop lock just down (or is it up?) from the Typhoo basin, and that one has all it's gates intact and well maintained (chained in the open position). I presume this is where the GU cedes to the BCN? Is this maintained for any reason does anyone know? The fact that there's a pair of gates at either end means that it can cope with a level difference in either direction. Don't remember seeing any paddles, however.

 

That's Warwick bar, and I think it had its gates reinstated or repaired fairly recently. It was a toll point (and gauging?) so the gates are there to stop boats rather than water, hence one set in each direction.

 

Richard

[alan_fincher]

As well as Worcester Bar, do you not, as you come in from Kings Norton, pass one or more narrowed points on the W&B that either do, or did have stop gates.

 

Or perhaps I'm confusing with somewhere else, I'm not sure. Certainly the cut narrows right down under one or more bridgeholes, despite the openings being very wide.

[Nine of Hearts]

... hence one set in each direction.

 

???? I find that one set of gates usually stops me quite adequately! Must have been some persistent (not to say reckless) boaters in them there days.

 

As well as Worcester Bar, do you not, as you come in from Kings Norton, pass one or more narrowed points on the W&B that either do, or did have stop gates.

 

Or perhaps I'm confusing with somewhere else, I'm not sure. Certainly the cut narrows right down under one or more bridgeholes, despite the openings being very wide.

 

There is a rotten gate at the exit of the bridge immediately before the Bournville works (& train station), I forget its number, somewhere in the seventies. And just beyond that there are two narrow points with disused gates, which I think are at either end of the aqueduct. At Selly Oak, as the canal passes under the railway, the canal sides come out and form what is almost a gauge lock there.

Edited November 17, 2008 by Nine of Hearts

[magpie patrick]

That's Warwick bar, and I think it had its gates reinstated or repaired fairly recently. It was a toll point (and gauging?) so the gates are there to stop boats rather than water, hence one set in each direction.

 

Richard

 

Your both right up to a point! it was a water control lock and thus could have differences, although as there is a parallel crest weir any surplus from one would flow into the other, I guess it prevented one canal from draining into the other as well. Until about five years ago it had no gates, then someone (not BW) paid for them to be put back as a "feature".

 

It was also a tolling point and it wasn't unknown to "trap" boats while they were tolled at various locations, sometimes with a swing plank over the canal both in front and behind, sometimes with gates.

 

The narrows on the W&B main line are emergency stop gates, originally installed in the second world war in case a bomb hit an embankment. The originals were mitre gates with bucket scoops mounted on them near the canal bed: the flow of water past the scoop would have pulled the gate closed. BW now prefer automated structures.

Edited November 17, 2008 by magpie patrick

[Nine of Hearts]

...in case a bomb hit an embankment.

 

Are you saying that the dastardly gerries had designs upon our chocolate supply as well as our chippies? The fiends!

Edited November 17, 2008 by Nine of Hearts

[alan_fincher]

Thanks both!

 

It's great when someone knows the facts, as guide books seldom tell you about anything but the most notable engineering features of the cut you are on.

 

I must admit when passing though a narrow, then "Second World War feature" is not the most obvious explanation I would come up with. Instinctively I would feel such a feature as older.

 

Alan

[Hairy-Neil]

That's Warwick bar, and I think it had its gates reinstated or repaired fairly recently. It was a toll point (and gauging?) so the gates are there to stop boats rather than water, hence one set in each direction.

 

Richard

 

I think you'll find Warwick Bar stop lock has two gates in each direction. It has been regated in the last 6 - 7 years. If it was just a gauging stop, why would it need gates in each direction?

[Hairy-Neil]

The narrows on the W&B main line are emergency stop gates, originally installed in the second world war in case a bomb hit an embankment.

 

I must admit when passing though a narrow, then "Second World War feature" is not the most obvious explanation I would come up with. Instinctively I would feel such a feature as older.

 

 

There are two railway tunnels under the Gas Street/Cambrian Wharf area, on the run in to Birmingham New St station on the Wolverhampton and Worcester lines. There's lots of wartime emergency provisions to be seen in the area, including the narrowing of the channel under the Cambridge St. bridge and the 'mini roundabout' near to the junction, though I believe the latter has since been repositioned to make the turn easier.

Edited November 17, 2008 by Hairy-Neil

[magpie patrick]

I think you'll find Warwick Bar stop lock has two gates in each direction. It has been regated in the last 6 - 7 years. If it was just a gauging stop, why would it need gates in each direction?

 

it also controlled water flow, but unusually they weren't worried about losing any spare water to the other company as there is a crest weir alongside. They only seem to have been worried that a leak in the other company's canal might drain theirs.

 

This might be because at the time Warwick Bar was built it was at the bottom of two flights of locks with no locks descending from that level, so neother company had much use for surplus water. Garrison Locks, on the Birmingham and Warwick Junction canal, were added later

 

 

There are two railway tunnels under the Gas Street/Cambrian Wharf area, on the run in to Birmingham New St station on the Wolverhampton and Worcester lines.

 

I'd forgotten about those, same principle applies though. the idea was tio stop the entire Birmingham Level being drained in the event of a catastrophic breach

 

 

 

Are you saying that the dastardly gerries had designs upon our chocolate supply as well as our chippies? The fiends!

[BuckbyLocks]

Several points to add. All four wooden gates on the Worcester Bar were still there until very recently, but there now appears to only be one metal one in the style of the lifting gates down the Northern Stratford. They had no top beams or anything like that, but were clealy visible as stop gates a lock length apart. It was very easy to trip over them if you were not looking where you were putting your feet when walking through with a boat.

Just round the corner, on the W & B at Granville Street, ie after the railway tunnel, the wooden stop gates have been replaced, with a truncated beam for balance.

 

Bournville Aqueduct was bombed in December 1940 and the canal was closed for at least 6 weeks. There are some pictures of the damage in the Temporary Exhibition at the Stoke Bruerne Museum.

 

The Warwick Bar is also a Junction. There was a toll office alongside it and an aqueduct almost alongside. The gates are recent replacements as part of the future Eastside Development to take place (very slowly) in that area. The Warwick and Birmingham Canal joins the Digbeth Branch of the BCN at the lock. although like the Worcester Bar there was no planned difference in levels.

 

The bi directional stop gates are still findable in the wartime narrowing of the approach to Farmers Bridge, but you have to get down close and personal to find them. The railway tunnel is between the narrows and the Island, which has indeed been moved slightly but that was built for the same reason, ie to stop all the water pouring into New Street Station in the event of bomb damage. All BCN staff were expected to fire watch and plank watch in the event of an air raid and stop planks were regularly put in overnight just in case. Stop gates were used in particularly vulnerable spots like the railway tunnels.

[alan_fincher]

Here's a good view of the other end or Worcester Bar stop lock.

 

 

It certainly looks like bi-directional gates were installed at some stage, (the footbridge not being an original feature).

Edited November 17, 2008 by alan_fincher

[alan_fincher]

And here's a picture of Warwick Bar from the TNC site....

 

[Nine of Hearts]

And here's a picture of Warwick Bar from the TNC site....

 

I know I've mentioned this before, but it was ages ago. On my way past there once (unfortunately not in the boat) I noticed a young chap stranded on that there central "island". He had jumped across as part of a dare, or somesuch, and hadn't thought it through. The narrowness of the island prevented him from taking the run up he'd obviously had when he vaulted the canal from the other side, and he couldn't get back. Being in possesion of my BW key, I tried to unlock the gates to allow him to clamber back across, but they are on a non-standard padlock. In the end, there was little I could do, so had to leave him there. (His friend on the towpath had a mobile, so they I wasn't leaving them completely at a loss). I still wonder if how they resolved their predicament. Bless 'em.

[RLWP]

I know I've mentioned this before, but it was ages ago. On my way past there once (unfortunately not in the boat) I noticed a young chap stranded on that there central "island". He had jumped across as part of a dare, or somesuch, and hadn't thought it through. The narrowness of the island prevented him from taking the run up he'd obviously had when he vaulted the canal from the other side, and he couldn't get back. Being in possesion of my BW key, I tried to unlock the gates to allow him to clamber back across, but they are on a non-standard padlock. In the end, there was little I could do, so had to leave him there. (His friend on the towpath had a mobile, so they I wasn't leaving them completely at a loss). I still wonder if how they resolved their predicament. Bless 'em.

 

I belive his ghost walks that central island even now...

 

Who's warehouse was alongside Warwick bar?

 

Richard