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Clyde Tidal Weir

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Clyde tidal weir from the west, 2007, Captain
Clyde tidal weir from the west

The present (2008) Clyde Tidal Weir in Glasgow is the fifth (technically the sixth) such structure to have been installed to control the river, and was completed in 1901, replacing an earlier structure at the same location. Collapsing in 1941 due to undercutting of the abutments, the weir was rebuilt in 1949 to give the present structure.

The history of the five weirs is described at length in The Swirl of the Pipes – a History of Water and Sewerage in Strathclyde by Bill Gow, published in 1996:

The Clyde Tidal Weir

Although not specifically related to the sewerage function the Clyde Tidal Weir became the responsibility of the Strathclyde Department of Sewerage following the local government reorganisation in 1975 and latterly the responsibility of Strathclyde Water Services. The present Clyde Weir is the fifth across the river at Glasgow although previous ones were all at different locations.

The first weir on the River Clyde was constructed of rough stones in 1772 to protect the foundations of the new Jamaica Street Bridge against the scour of the river in spate and to protect the water supply of the city. The deepening of the river and the development of Glasgow Harbour had made the shallow foundations of the bridge vulnerable and consequently the weir was built a short distance downstream of the bridge creating a constant river level upstream. However the weir had the disadvantage of preventing navigation up the river to Rutherglen and was also blamed for causing flooding at times of high river flow.

In an endeavour to alleviate the flooding caused by the close proximity of the weir to the bridge piers the weir was relocated 50m downstream of the bridge in 1803.

In 1829 Parliament passed the Bridge Trust Act which gave the Bridge Trustees (in essence Glasgow Town Council) powers to rebuild the Jamaica Street Bridge and to demolish the old bridge including the weir. The new bridge was opened to the public on 1 January 1836 but the weir was not removed until some years later.

Meanwhile a meeting had taken place on 24 January 1835 between a committee of the Bridge Trustees, the Directors of the two Water Companies and representatives of the local proprietors and other interested parties in the upper navigation of the river “with a view to the construction, at the joint expense of the parties interested of a Weir and lock below the old bridge opposite Stockwell Street or such other works in the river as may appear expedient for preventing damage to the water-works and at the same time not obstruct or impede any right of navigation above Glasgow to which landed proprietors in the upper parts of the river have a legal claim”.

The Water Companies had pipes laid across the bed of the river and were concerned that if the weir was removed and the water level dropped, their pipes may be endangered. In addition the abstraction of water from the river relied on the constant level of water upstream of the weir.

Consequently the weir at the Jamaica Street Bridge was retained although in February 1837 a committee of the Bridge Trustees recommended that the weir should lowered 2 feet.

This proposal was strenuously resisted by the Water Companies and by the factory owners who drew their water from the river but countered by the Burgh of Rutherglen, and the Duke of Hamilton and others who took legal action against the Bridge Trustees to force them to totally remove the weir enabling navigation upriver. Not to be outdone the Water Companies and others appealed to the Court of Session against the resolution by the Bridge Trustees to reduce the height of the weir.

Stalemate continued until the Clyde Trust Act of 1840 gave powers to the Clyde Trustees to deepen and improve the river and harbour and to remove the weir from the Jamaica Street Bridge. The Bill had been opposed by the Water Companies but agreement was reached by the insertion of a clause into the Bill requiring the Clyde Trustees to maintain the original weir until the new was constructed immediately downstream of Stockwell Street Bridge. The Act also made the Trustees liable for any losses suffered by the Water Companies and by printing and dyeing works at Barrowfield and Dalmarnock through failure to maintain upstream water level.

The third weir located downstream of the Stockwell Street Bridge was constructed in 1842 and the original weir at the Jamaica Street Bridge was finally removed.

On 21 July 1845 the Bridge Trustees obtained Parliamentary powers to rebuild the Stockwell Street bridge. The new bridge was to have deeper foundations and therefore the weir was not required for protection of the abutments. A weir was still required to maintain upstream water levels and the Act required the construction of a replacement weir 130 metres above or to the east of Hutchesontown Bridge. The Act also stipulated that a lock should be built into the weir to enable navigation past the weir. On 9 October 1851 the Bridge Trustees accepted an offer from a Mr. York to remove the old weir for £1,800 and to erect a new one, with lock, for £3,182. The lock was designed to allow the passage of barges and was 22.7m long by 7.6m wide with a pair of double gates. The weir itself was constructed of regularly built masonwork with rows of sheeting piles on the upper and lower sides and was engineered by James Walker of London. The new weir was completed in 1852 and subsequently the one at Stockwell Street was removed.

In 1858 the Clyde Trustees obtained an Act of Parliament consolidating and amending their previous acts. The Bill had been opposed by the Magistrates and council of Rutherglen and upper heritors who complained about the serious obstruction to navigation caused by the new Weir. As a result the following clause was inserted.

“And whereas, under provisions of the Act 8 and 9 Victoria cap. 133(the Bridge Act of 1845), a Dam or Weir was constructed, at the expense of the Clyde Trustees, across the River Clyde, near, and the east side of, the Hutchesontown Bridge; and whereas, the said Dam or Weir obstructs the navigation of the said river, and impedes the tidal scour thereof, and the removal of the said Dam or Weir would restore the upper navigation of the said river, and thereby open up a convenient means of shipment of coal from the adjacent mineral fields, and of other commodities, to and from the Burgh of Rutherglen and other places to the east of the Harbour of Glasgow; and whereas, the principle object for which the said Dam or Weir was constructed was for the preservation of the level of the water at the works erected on the said river for supplying the City of Glasgow with water, which works are expected to become unnecessary as soon as the supply of water from Loch Katrine, authorised by ‘The Glasgow Corporation Waterworks Act, 1855’, shall have been introduced into the said City, and it is expedient that the said Dam or Weir should be removed as soon as the same can be done, consistently with the rights and interests for the protection of which it was erected. Therefore, nothing in this Act contained shall authorise The Trustees (the Clyde Trustees) to maintain the said Dam or Weir after the said rights and interests shall have ceased, or shall have been extinguished by Parliament.”

Loch Katrine water was introduced to Glasgow on 14 October 1859 and abstraction from the river thereafter discontinued but no immediate steps were taken to remove the weir.

In 1864 it became necessary for the Bridge Trustees to apply to Parliament for powers to re-erect the Hutchesontown Bridge. With the agreement of the Clyde Trustees a clause was inserted in the Bill for the total removal of the weir but this resisted by a number of companies who abstracted water from the Clyde for use in their factories. Although passed by the House of Commons, the House of Lords insisted on an amendment to the Bill allowing for compensation to be paid to the factory owners from any damage caused by the removal of the weir. This was unacceptable to the Bridge Trustees who withdrew the Bill and resubmitted it to the next Session of Parliament omitting all provisions relating to the removal of the weir.

However pressure to remove the weir continued because it was also blamed for the flooding of the low-lying parts of Glasgow. As development spread eastward an increasing number of properties were at risk of inundation from the river in spate.

In 1865 discussions were held with the Water Commissioners, who were promoting the Water Works Bill, the Clyde Trustees and the factory owners regarding the weir and it was agreed that provision would be made in the Water Works Bill for the removal of the weir. This was opposed by a section of the Town Council on the grounds that the removal of the weir would destroy the amenity of Glasgow Green. However after long discussion and division the Council voted not oppose the Bill and it duly received Royal Assent on 6 August 1866. The 1866 Act allowed the Water Commissioners to develop a river supply pumping station and associated pipework to supply those factories which previously abstracted from the Clyde. The Weir was not to be removed until the factories were connected to the new supply. Delays in completing the low level supply and disagreements with the Clyde Trustees (who at the time were responsible for the maintenance of the weir) led to the Trust obtaining an Act transferring responsibility for the Weir to the Water commissioners. This concentrated the efforts of the Water Commissioners and following completion of the low level water supply the weir and lock were finally demolished on 20 October 1879.

While the removal of the weir was supported by the Clyde Trust, its Engineer James Deas had reservations and these were confirmed within a short period. In a report of November 1885 he described the removal of the weir above Hutchesontown Bridge as being “an unmitigated evil”. Firstly it caused erosion of the river banks resulting in considerable riparian owners in protecting their property. Secondly it caused the sewage which had previously discharged to the river below the weir to be washed upstream with the tide, “while at low-water the bed of the river exposed to view in all its slimy hideousness”. Thirdly after removal of the weir boating was very much dependent on the state of the tide whereas previously in summer evenings the river was crowded with rowing craft. Finally the removal of the weir caused thousands of tons of material from the bed of the river to be washed down to the harbour causing delays to navigation and a 63% increase in dredged material removed from the river.

In spite of these problems the Royal Burgh of Rutherglen were strongly opposed to any replacement weir which they considered would be illegal. However a solution emerged following an inspection by Glasgow Corporation of a new liftable weir which had been erected at Richmond on the river Thames.

The Present Weir

In 1894 Glasgow Corporation promoted the Glasgow Bridges, etc, Bill which sought approval for a liftable weir to be constructed across the River Clyde about 110 metres upstream of the Albert Bridge. The Bill was opposed by Rutherglen and the Rutherglen Shipyard on the basis that it would restrict navigation. The counter arguments were that a new liftable weir would be no more of a restriction than the existing bridges; that navigation upstream would be available at any time and not just at high tide which was then the case; and that there was minimal commercial use of the river to Rutherglen apart from the shipyard. A second objection was raised by an upstream riparian owner regarding the likelihood of flooding due to the weir. However it was pointed out that the gates of the weir could be lifted clear of the water when the river was in spate. The argument in favour of the weir won the day and the Act was passed in 1894.

Having procured the necessary powers the Corporation place a contract for the construction of a liftable weir. The work was hazardous with many difficulties resulting in the abandonment of the original contract and a new contract was entered into. Finally the work was completed in 1901 after Sir Benjamin Baker, the designer of the Forth Railway Bridge, had been called in as a consultant in view of the difficulties experienced in sinking the foundations.

The structure comprised a north abutment, south abutment and two river piers all connected by a dual walkway and supporting three equal 24 metre long liftable gates hydraulically operated and born by chains carried over sprocket wheels. Back balance weights, each weighing 25 tons, were housed in recesses on the piers and abutments. The three gates when in the ‘down’ position rest on granite sills built into six monolithic concrete caissons 4m wide and 14m deep. The 3.7 m high gates are now raised by electric motors. As well as supporting the walkway the arches carry two 675 mm diameter water mains across the river. The level of the sill is 2.13 m below ordnance datum (Newlyn) and the impounded water level is 1.7 m above ordnance datum.

The weir is manned 24 hours a day by 4 operators and a chargehand on a shift basis. Water levels are taken using a depth gauge and an ultrasonic level recorder and the weir gates adjusted accordingly. When the river flow is low the gates are dropped until they are on the sill thus impounding the water upstream. During high flows in the river the gates are progressively lifted and in extreme conditions can be lifted clear of the water, thus preventing any obstruction to the natural river flow.

By prior arrangement the gates can be lifted to allow boats to pass up or down the river. The gates operate always as underflow sluices and the water is not allowed to flow over the top of the gates.

- The Swirl of the Pipes – a History of Water and Sewerage in Strathclyde.[1]

Additional information

Glasgow council provides further information regarding the history of the weir, noting that the fourth weir of 1852 stood from 1851 until 1880, when it was replaced with a weir containing a lock.

Describing the weir of 1901 as "The first tidal weir", it goes on to describe the collapse of the original structure when the abutment foundation was undermined by scour in 1941, resulting in its repair in 1943 and replacement by 1949 by the structure in place today (2009), which also serves to carry large diameter pipes across the River Clyde.[2][3]

River access for boats

As noted in the history of the weir, there were various issues regarding access upriver towards the Rutherglen area, and this led to inclusion of a lock to allow the passage of vessels through the weirs constructed after 1850. During the 19th century, the area was known for its boat and ship building, and in 1884, Rutherglen shipbuilder Thomas Seath constructed six small screw steamers for the Clyde Trust, each able to carry between 235 and 350 passengers, and destined for service between Victoria Bridge and Whiteinch in the west of Glasgow. By 1896 there were 12 of these vessels service, and they carried two and a half million passengers annually. This was not to last though, and following the opening of the underground system in 1897, and introduction of electric trams, they had been withdrawn by 1903.

The later weir has no lock, but the gates can be lifted to allow boats to pass.

As can be seen in the photographs, the gates carry signs to warn owners not to attempt to pass the weir as not only is prior permission required, but passage is only possible at high tide. This means that there will usually only be about seven or eight instances during each month when the tide is high enough to ensure that boats can pass the restricted opening of the gate and clear the sill, and that the water level on each side of the weir is similar before the gate is opened, otherwise the resultant water current could be a problem.

In order to traverse the weir it is necessary to contact the council's Land Services at least two weeks prior to the move. They will provide a date and time when the gates will be opened, to accommodate the crossing. An allowance of 20 minutes either side of the appointed is allowed to complete the move, after which the gate will be closed, even if a scheduled boat is seen approaching, but late. The times given are dependent on the tide, and can fall at any time of the day or night.

Photographs

Clyde tidal weir from the west, 2008
Clyde tidal weir from the west
© Thomas Nugent
Upriver, or east facing side, 2008
Upriver, or east facing side
© Thomas Nugent
Seaward, or west facing side, 2008
Seaward, or west facing side
© Thomas Nugent


References

1 The Swirl of the Pipes – a History of Water and Sewerage in Strathclyde, p107, Chapter 6, Bill Gow, 1996.

2 Pipe Bridge and Weir – 1901 (rebuilt 1949), Glasgow council.

3 The Pipe Bridge and Tidal Weir, Glasgow council

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