THE NORTH CIRCULAR ROAD CANAL AQUEDUCT
The canal was opened in 1801 and an embankment was needed to traverse the valley of the Brent and an aqueduct had to be constructed to carry the Paddington Arm of the Grand Union Canal over the River Brent. This work was necessary to follow an approximate 100 foot contour thus requiring no locks on the 12-mile level stretch from Bulls Bridge Junction (south west of Southall) to Paddington Basin. The navvies (from navigation canal diggers) used the dug earth to create the banks required for bridges (cut and fill). This technique was used more extensively for the future railway lines.
Forward to 1933 and the construction of the North Circular Road. The Brent was transformed into an almost straight line concrete trough between the Harrow Road (with a tunnel under the railway lines which were carried by the locally named Seven Arches) and the Piccadilly Line tracks. The Brent still went through the original arch but no more meandered through the Twyford Abbey grounds. The North Circular Road passed under a very solid looking concrete bridge over the road. Some Senior Citizens may remember the Middlesex Shield dated 1934 on either side of the bridge.
On 2nd March 1939 that strength was enough to repel IRA bombs planted either end of the aqueduct. But there were small leaks over the North Circular for the canal to be blocked at Manor Farm Road bridge, and the nearest Park Royal road bridge. The ‘plug’ was pulled and the canal water emptied into the Brent scouring that shallow river of all the sediment. Now that I have seen the 1939 clips the decision to repair the cracks could not have been lightly taken.
A repeat operation took place in 1962 (see photos below) when a leak developed which was enough to flood the North Circular and caused it to be closed for four days. Once again the canal was drained into the Brent.
By the 1990s the road traffic hold-ups were enormous and a grand scheme was planned to enlarge the North Circular Road between the Harrow Road and what was to become the gyratory system at Hanger Lane. This required a completely new aqueduct bridge, and a high-technology system was used to make a prefabricated structure to be placed alongside the 1934 aqueduct and then sliding it into position after removing the old bridge, and extending the span. This solution minimised the time the road was closed. The major contractor Balfour Beatty supplied the 1992 onwards photos of the construction activity.
If anyone knows of a picture or description of the aqueduct and embankment before 1933 then please let me know. Some of the comments above are based on assumptions.
When most of the residual water has gone the 'cut' can be barricaded. Then dig to the bowels and inspect the plug hole to the pipe to the Brent.
Photos taken by Tony Rock from the Mount Pleasant footbridge to the Abbey Estate. The first is looking east towards Celotex and the aqueduct. The second is looking west with the Carlyon Road back gardens on the left behind the poplars. The amount of domestic tipping revealed was nothing compared to the factories' dumping on the stretch to the Ealing Road bridge, or the Greenford Industrial Estate.
Concurrently on the North Circular Road there is no through traffic (was it for four days?) and water can be seen gushing at pavement level.
The fire tenders are pumping via the 'master' tender which is sending water through that huge hose over the embankment and into the Brent. In the longer view in the photo immediately above taken from the bank of the Willesden 'tip', the Celotex Head Office gets a grandstand view. As do the builders on what is to become the Fire Auto and Marine office block. Remember Emil Savundra?
The water is still leaking but the fire tenders are winning.
The filmed interview took place at the earlier plug-pulling time.
Here are another three photos by Trevor Uff (see 1959). Trev has also provided a time-line of Easter 1962. That places the Easter weekend at 20 to 23rd of April.
How fortunate for the business world. Not so good if you were going away or visiting someone north or south of you in London. Mind you, not so many people had cars then so you could go right through Central London in a fairly quick time!
Taken from the towpath side looking north-east. The Willesden tip is beyond the bridge. Looks tidy, doesn't it? But if you went beyond that, as an adventurous youth must do, there were the Borough of Willesden lorries pouring all types of waste into what I suppose was described as a landfill site. Without climbing the slopes you knew the lorries were tipping by the number of seagulls wheeling overhead!
Trevor has gone down to beach level for this photo. Look at that wheel. Disgusting. Mind you it is a long standing feature of fly tipping over the centuries. If you want to dig up historical items then go to the Thames foreshores, river beds, stream beds, and even wells.
Looks something like the same row of poplars in a previous photo. With the industrial units on the other bank this might well be the stretch which bends round to the Ealing Road bridge. With the footbridge behind and to the left of the picture that would account for some excessive tipping from the Abbey Industrial Estate.
Well, we can be certain about this one. With Middlesex House (being built?) in the background, we must be standing on the Manor Farm Road bridge. This is the 'pinch-point' where the canal narrows to not much more than a barge width. At this point a barricade was erected to stop the canal waters from entering the stretch of canal from here to the first Park Royal road bridge. Thus allowing work to take place on the damaged aqueduct.
Note the scouring effect of the canal bend on the towpath side such that no sediment has built to form a 'beach' on the right hand side as we look at it.
Thank you Trevor for all these photographs. Everyone thought the barricade was uninteresting, so no photograph was taken. Perhaps someone still has it but thinks it is 'uninteresting'? Not so! Historians like all the detail, especially when it might tell us something about an 18th century bridge.
The 1992 new aqueduct
As part of the A406 North Circular Road redevelopment the road junctions were improved and the main road was widened to three lanes between the Harrow Road and the new gyratory system over the A40.
The main contractors were BALFOUR BEATTY and they kindly supplied these tremendous colour pictures. Pictures added 18.11.12.
Wave goodbye to the 1934 bridge! The canal had been blocked so that the old bridge could be demolished while the North Circular was closed overnight and the new bridge slid into position. So, minimum disruption to traffic.
Traffic going towards Hanger Lane, and on the left piles of rubble going nowhere, at the moment.
The pedestrian walkway being lined up for a fitting!
A number of the 22 photos supplied by BALFOUR BEATTY were taken from the bucket of an extending crane for very high structural work. Clearly no crane could be this high, so a helicopter was used as well.
There are two items in this photo which are of interest to an Alperton Local Historian. The first is a rare, but long distance, viewing of the original aqueduct arch which is just about coming up to its 213th birthday!
Also, celebrating only its approximately 70th birthday is the World War Two concrete pillbox on the far bank of the canal. Look for the space between the office block and the River Brent on this side of the canal, and move 'up' from there.
This pillbox has a twin on the bank of the main line northbound railway. It is usually obscured by the green of much growth, and the bulk of the office block on the corner of Heather Park Drive and the slip road running alongside the North Circular to Stonebridge Park Station and the Harrow Road. As the slit on the side of the pillbox could only take a rifle or perhaps a machine gun, one imagines that a couple of rounds from an armoured German tank would be the end of the occupants of the pillbox.
Are these two pillboxes the closest surviving ones to Central London?
Let's stay on history while we're at it.
From the aqueduct going northwards on the slip road we come to a white structure. That's the now-famous Ace Cafe. The next building we come to, is the office block 'bulk' mentioned above. To its right is the main arch of the bridge built about 1835 for the London to Birmingham Railway, which opened in 1837.
The main contractor then faced the same problem as the canal builders 35 years earlier. How to raise the level of the valley of the River Brent. Of course it was the same solution - cut and fill. The fill came from the Oxhey cutting, and we can be sure it was carried by wagons on the lines.
The pleasing design of the pedestrian walkway and the towpath barrier can now be seen in sunny daylight.
Always makes a difference when the camera-person chooses about midday on a sunny day, doesn't it? Taken from the top of the hotel which now occupies what was an office block.
All eight lanes are operational under the single span. You can just make out the western end of the central pier. On the other side of the canal is a long grey storage structure, with the pillbox next to it starting to disappear behind natural growth. As always happens when you clear a working area and then do nothing with it, nature starts its colonisation all over again.
No it's not just to keep the barges apart. There's little enough traffic anyway!
Undoubtedly the structure on top of the pier at this end will give access to a much more modern and efficient method of draining the canal if required.
The towpath is now quite a popular cycling and walking route. Incidentally, the original 18th century plan had a towpath either side. But the nearer they got to Paddington, the more difficult became the negotiations to purchase. So the canal was opened with just one towpath. Now you know why the original road bridges were quite so humpbacked. There was less span required.
There are another 15 BALFOUR BEATTY photos, but three are similar to three above so just 12 project photos follow.
An early stage of preparatory work for the new layout of roads. The railway bridges for the 1934 North Circular have been altered, extended, or removed. So two of the original Seven Arches have gone. One of them was the single track bridge which took a line behind the factories in Heather Park Drive. But the line pre-dated the factories by at least 20 years. Then the line curved ninety degrees left to finish in the present green open space behind Beresford, Kenmere, and Heather Park Drive. Real oldies like me remember the steel buffers which were the only thing left by the 1940s. I haven't yet seen it in print but there was a World War One munitions factory in this area. There was also an open water storage pit sited somewhere close to the Highcroft end of the Heather Park Hotel. It briefly figured in the news in the 1930s when a young lad drowned in it.
This single track line and bridge was in front of the first bridge you see above (the London to Birmingham Railway one).
The five bridges taken from the Harrow Road end (from the top of Middlesex House?). So the Bakerloo Line bridge is in the foreground.
In the distance the new Abbey Road access to Park Royal is taking shape. Apart from that, all the drivers must be thinking all this managing and manoeuvring of traffic better be worth it!
Meanwhile at Monks Park... the human windscreen wipers have just two prospects on the North Circular about to cross the Harrow Road towards Hanger Lane.
And in the centre of the picture they are getting ready for something.
From on high we can see the long u-turn the Harrow Road traffic has to make to go on towards Harlesden.
The Brent has been blocked so that work can take place extending the road level space.
From here the Brent ends its meanderings from the Welsh Harp where it was blocked in 1834-5 to provide the reservoir to supply the canal with top-up water not far from the first Park Royal road bridge. This measure was taken because the first reservoir (now Ruislip Lido) was not supplying enough.
The Brent now has two extremely strong walls, and the sleepers (is that the right word, or are they girders?) are the foundation for the new surface feature.
The Monks Park buildings don't seem to have changed much in the last 60 years. But the shop owners? Ah - that's something else!
Our friendly extending crane driver gives us a top-down look at the sleeper-laying. The yellow hoist is delivering another one. From here also we can see that the same exercise has taken place on the other side of the road.
It's looking eerily quiet and clean. The Stonebridge Park Station corner is unrecognisable from what it was.
Ah... this was what it was all about. Six-lane Harrow Road over the top and six-lane North Circular passing underneath. Must be early Sunday morning surely?
How pleasant. Those sleepers are supporting a decorative pedestrian area.
Entering the underpass going Neasden-wards. The inside lanes are coned off... perhaps they haven't quite finished?
Hooray... ten lanes open. All that hassle whilst being constructed starts to pay off.
Meanwhile the other underpass lets Park Royal traffic enter via Abbey Road.
And for our final photograph we can look down from the aqueduct parapet and admire the fairly heavy traffic load making its way calmly to the gyratory system.
Pessimists would say it's all just got you to the next bottleneck quicker. But they are ignoring the benefits to all the local traffic users. And when the traffic is not so heavy, you get through to the A40 quicker.
If you want to moan wait until you get to Ealing Common!
OK - NOW LET'S GET BACK TO THE AQUEDUCT!
On 17 May 2011 two friends and I took the advantage of a lovely day after a dry spell (yes... we do get them!) to take some photos of the Brent aqueduct.
So I took a rope and two of us went safely down to river level. So here is the first photo with me in wellies and the water only coming two thirds the way up them in the deepest place.
The 211 year old arch brickwork had been rendered by the 1990s contractors, so I don't know whether any remedial work was done on the brickwork along the length of the tunnel. But at least you can see that it was quite a wide arch.
As you can see it is quite long. It has to traverse the banking on either side as well as the canal and towpath.
We are looking north towards The Ace. The metre's height of containing wall for the river waters IS new.
You may well be wondering what you are looking at. It's the very last section of drainpipe coming down from the canal draining mechanism.
There is apparently no need for regular maintenance. The deluge of canal water if it ever comes down again would move anything out of its way.
Anyway I plucked up the courage to trample over the rubbish and take this much more satisfying picture of the tube going up to the, presumably, watertight 'plug'.
Ah! Now I understand how that light rubbish got higher up.
When the river waters are swollen rubbish eddies backwards slightly into the drainage trough. The lighter stuff is carried higher and gets snagged, or pushed, in some way. The heavier stuff (branches) is left on the lower slope when the waters recede.
The first step is to locate the 'plug' to the metal drain tube into the Brent. Then the plug must be grappled (how did they do that?) and hoisted.