BrownhillsBob's Brownhills Blog

The Black Cock Bridge viewed from the South last Saturday afternoon.

In the last couple of weeks, I’ve compiled two posts that questioned the oft-repeated local legend that the cottages by the Black Cock Bridge in Hall Lane, Walsall Wood, were originally built at the level of the canal and sank due to subsidence. In my second post, I laid out some of my research in to the landscape around the area, formerly known as Bullings Heath. In this post, I’m going to look at the star of the show: The canal bridge itself.

First of all, I’d like to thank all of the readers who’ve contributed so wonderfully to the group knowledge on this topic – but this particular post wouldn’t be what it is without the careful thought and contribution of readers [Howmuch?], [Katyusha] and top archivist and researcher Paul Ford from Walsall Local History Centre. I had great fun researching this and I hope this comes across in the writing. Any and all input is welcome. Together we’re nailing our local history.

I caution readers once more that this is a long post. Take a run up, read it in chunks, whatever works for you. I can’t see a way to break it up without destroying the flow.

Aerial imagery of the Black Cock Bridge and Bullings Heath area, captured from Google Earth. The image was originally taken in Summer, 2007.

The Black Cock bridge in Walsall Wood carries Camden Street over the Daw End Branch canal, and is named after the nearby pub. I don’t currently know when the present incarnation of this overbridge was built. It consists of local Utopia engineering brick abutments, wing walls and supports, with a deck constructed from formed, heavy girders with hot riveted joints. The deck has guard rails made of wooden planks with angle iron supports, forged and hot riveted onto the webs of the external cross members. From memory, the now demolished Clayhanger bridge was of a similar construction. The lack of welding involved and the shape of the metalwork, leads me to suggest that this bridge was constructed anywhere from the late Victorian period – 1880 – to about 1910. I’d tend to go for around 1890. The bridge has comfortable clearance to stand underneath, and has vertical under walls.

These are late victorian construction techniques. Think of the old ‘Iron’ pedestrian Silver Street Bridge, which I suspect was cotemporary with this one. Very similar jointing techniques.

There’s also a 1980’s pedestrian footway erected on the north side of the road bridge. For the purposes of this discussion, it doesn’t exist.

Since the canal was opened in 1800, one must assume an earlier crossing existed. Indeed, the Yates Map seems to show one. This would probably be of a brick arch design as seen further up on the Rushall canal. One would expect any such structure, facing increasing traffic loads, to be in need of replacement 90 or so years later.

Paul Ford posted a comment on my original post ‘A sound foundation‘ in which he recounted some notes of interest from the minutes of the Brownhils Urban District Council:

Brownhills UDC minutes: 20 Dec 1905: the ‘canal company were on about raising this bridge [Black Cock] and that now would be a good time to raise the approaches’: Resolved – this be done.

Brownhills UDC minutes: 21 Aug 1918: Surveyor’s report… ‘with regard to the bridges at Clayhanger Rd, Black Cock and Hollander’s Lane… The surveyor pointed out that owing to the subsidences caused by mining operations and the periodical raising of the canal to maintain the original levels the approaches were becoming very steep and dangerous especially to vehicular traffic…. if it continued it would eventually end in one part of the district being cut-off from another…’

These comments are telling. They show that as the one constant factor in the history of this area, the canal height of 473 feet, was aggressively maintained. Indeed, it had to be. Any leakage or poor banking that caused the overall level to drop would be perilous to boats and render the canal unusable. I also have no doubt that subsidence occurred, and caused problems for the canal. This is actually visible in the structure of the bridge itself. Thanks are due for the eagle eyes of my companion, who spotted a major indicator.

There are two clues in this photograph.

The adjacent photo shows the canal approach to the bridge from the southern, Walsall Wood side. If one studies the brickwork, it’s generally smooth and consistent, apart from some areas of re-grouting and repair. However, there are two peculiar features. Up to a height of about two and a half feet there is a cast iron roller bracket casting set into the vertex of the under bridge. This was to protect against the cutting effect of horse tow ropes that would saw away at the brick as the lead horses rounded the bend. Whether this ever had a roller is unclear, as one can see the rope notches worn into the metal down it’s length. There is one of these brackets either side of the bridge. They are both set way lower than any such devices I’ve seen before, which usually run to about five or six feet in height – however, the base of these ironworks cannot be seen, suggesting they are buried beneath the towpath. This implies that the canal towpath has risen in level by about three feet since they were erected if they are of normal dimensions..

The other peculiar feature of the bridge is that the deck is sitting on timber planks, around six inches thick. These are of a considerable age. They sit in a recess in the brickwork that could, conceivably, have held the bridge deck without them. Directly under these timbers are voids in the brickwork in which it is practical to imagine a jack being fitted. I think these timbers have been inserted to increase the clearance height of the deck.

There is further evidence of this height build up on the eastern Camden Street approach from Walsall Wood. One can see that where the wing wall ends, the pavement leading to the deck is also filled with wood.

Anything to hand seems to have been used to build up the approaches. Wonder when this dates from? 1905, perhaps?

Whilst we were under the bridge, we noticed that someone, somewhere is concerned about the fabric of this edifice. There are datum marks and references in several places. On the eastern abutment, a 30 inch fissure in the brickwork is grouted, with the date 8-11-91 scratched into the fresh mortar. This itself is obliterating a similarly etched surveyor’s mark from 1970. A horizontal datum line in yellow wax crayon drawn across the crack no longer aligns, whilst a painted red marker underneath runs from a deck girder, over the insert plank and onto the brickwork. This is serious monitoring

Somebody is watching this bridge quite closely. I find that reassuring.

I mentioned in my last post on the subject that there was a retaining wall behind the cottages in Hall Lane that looked contemporary  with them. This is a solid, continuous wall and gives little away. However, diagonally opposite on the northeast, there is another conundrum. This one is altogether more mysterious.

1902 map fragment showing the lost square, with well central.

Throughout all the map geekery of the previous article, I advised you to keep an eye on what was happening in the space between the north of Camden Street and the canal. The maps of this little parcel of land are quite interesting. In 1884, there’s little there except what appear to be a handful of sheds or outbuildings. By 1902 there is a square – possibly houses or workshops – with a well in the middle. Still there in 1919, by 1938, they seem to have gone. I have no clue what these places were or who owned them. Their location today is nothing more than a swampy sump.

Hopping off the footpath onto the canal bank, a walk of five yards or so brings you alongside a heavy brick retaining wall, again made from locally made Utopia engineering bricks. This wall terminates at towpath height, so the incautious explorer might step off it inadvertently. It increases in height over a matter of 30 yards, until it is about 10 feet high, the ground beneath falling away to damp, lush woodland punctuated with discarded rubbish. This retaining structure finishes in a perpendicular, thick buttress. This wall is clearly bearing the weight of the bank and canal behind it. It leaks. The ground beneath is sodden, and has been for a very long time. The base of this wall is probably as old as the bridge.

The top of the northern retaining wall is at ground level. Take care if you go exploring.

The wall leaks at ground level, but it’s evidently been doing this for years. Note how the brickwork has three distinct strata – suggesting that it has been added to three times.

I say ‘base’, because the wall is stratified. The bottom 50% was clearly built in one go, the next 40% in another and the final few courses separate again. This may well suggest sinking of the land, and the need to build the canal up. However, this seems to be to a greater degree (maybe four to five feet) than is evident at the bridge. However, it’s important to consider the lost square; whatever that was had buildings here – this would surely have been a rear wall. Maybe something complicated the development of the brickwork here. Perhaps the leak – clearly audible from a seam near the bridge end – led to the abandonment of whatever was once here.

[Howmuch?] remembers that as a child, there was an old pump here. It had a pipe that led back over the wall into the canal, clearly returning the leaking water to whence it came. He says that if you bounced up and down on the casing, the pump would start. This would be in the early sixties. It seems fair to assume that this area once had a ‘floor’, and maybe still does, and has filled up with detritus and leaf litter. I wonder if the well is still in there somewhere? We could find no trace of the pump.

This wall too, is covered in surveyor’s marks and several datum.

That’s one hell of a strengthener. This must have cost a fortune to build.

From the evidence presented by the Black Cock Bridge and it’s environs during this exploration, and my previous analysis, I’d say it’s clear that the area subsided at some point, but I don’t think it was ever as severe as claimed. As Stymaster and others point out, I think the idea of a contour canal is very rigid, and with the quantities of spoil that would need to be lost, building the odd few embankments wouldn’t be too big a task in cutting the entire canal.

The canal towpath and bank has clearly been built up. The current Black Cock bridge is not original, but it’s old, and in all likelihood pre-dates the adjacent cottages. My feeling is that the area sustained a period of subsidence soon after the mining commenced, that mostly predated the construction of the houses whose slippage I question. I think the subsidence has probably been of the order of three feet, but we cannot also rule out the possibility that any embankment settled since it’s construction. The strata in the brickwork of the northern retaining wall also suggest a sudden need to increase the height. However, this may be complicated by the interaction of buildings that seem to have existed here.

Engineers are evidently still monitoring the condition of these old structures. When they reach their finale, one wonders how they will be replaced. Such work will clearly present a challenge to structural surveyors and designers.

This will certainly not be my final word on the subject, and is intended merely as a discussion point. I will continue to research this, and hope readers will give it further consideration, too. The ideas I present are not final, authoritative or nescessarily accurate, but I’m willing to revise them should further evidence come to light.

Clearance is still good enough that passing boaters don’t have to duck.