The New Tidal Weir at Glasgow Green

Sketch of structure with sluices up

Glasgow Herald, Thursday December 26^th 1901

This structure, which is to be opened by the Lord Provost on Saturday, is a somewhat unique type of cross-river bridge, the only similar one in Britain being across the River Thames at Richmond.

The Lord Provost of Glasgow at that time was Samuel Chisholm.

Somewhere about 20 years ago, after much discussion, it was decided by the then Town

Council that the old weir, which consisted of a rough bank of stones and boulders of various

sizes submerged at high water, and which extended across the river about 100 yards east of

Albert Bridge, having a lock for the passage of boats at it’s north-end, should be removed, in the

expectation that various good results would follow, including less dredging in the harbour, and

unimpeding navigation as far as Carmyle.

Far from improving maters, however, the immediate effect of this step was an enormous

amount of scour in the river bed, causing the river banks for long stretches to cave in, and also

seriously injuring the foundations of several of the river bridges, the old Rutherglen Bridge being

the first to show dangerous symptoms, which ultimately led to its being taken down and replaced

by the present handsome structure, whilst the amount of dredging in the harbour was probably

increased by the deposit of the scoured-out material.

After considering the question for some time, and studying the result of the new weir just them

finished at Richmond on the ‘stoney’ principle, the Corporation decided to erect a similar structure

on the site of the old weir, as a result, Parliamentary powers were obtained in 1892.

The work of construction was not begun until a year or so later, but following very severe

flooding, the coffer-dam, which had been constructed by the first firm of contractors who

undertook the work, was undermined and a great amount of damage done, the final result

being that the Corporation took over the works from them. Sir Benjamin Baker, the well known

engineer, was called in by the Corporation, and, after a careful examination, be recommended

the carrying out of the works by the sinking of a series of caissons extending from bank to bank

by the pneumatic process, which he had employed so successfully at the Forth Rail Bridge.

Fresh designs were prepared under the supervision

of the City Engineer, and a new contract was let, the successful offerers being Messrs

Morrison & Mason Limited, and work was again resumed in the latter end of 1896.

The firm of Morrison & Mason specialised in building waterworks, docks, railway

construction, tenements, villas and public and commercial buildings.

Amongst some of their work in Glasgow between 1875 – 1908:

The General Post Office, George Square

Her Majesty’s Theatre (Citizen’s Theatre), Gorbals Street

Clyde Navigation Building (Clyde Port), Broomielaw

Great Western Road Bridge

Ruchill Hospital , Extension to Rottenrow Hospital

Colliseum Theatre

And possibly most famously – Glasgow City Chambers (1882 – 1890)

Progress Of The Work

Since that date the work has been quietly but steadily carried on under many difficulties,

particularly during the winter seasons, which since the work was resumed have been of a

very wet description, the river being in flood to a greater or less degree for weeks at a time.

The delay has arisen chiefly from the great difficulty which was experienced in sinking the caissons

through the solid masonry foundations of the old lock already mentioned and through the boulders

etc., forming the old weir, which had made their way many feet down into the sandy bed of the

river, and caused a great deal of trouble when getting below the cutting edges of the caissons.

The series of sill caissons, which were sunk right across the river, had to be finished one by one,

the work at one being completed and the water-way restored before another was started,

this being absolutely necessary owing to the amount of scouring action which immediately took

place when the water-way was restricted by their presence. As only four men could be employed

in one of these caissons at a time, the rate of speed was necessarily slow, and the daily amount

of sinking accomplished, even in the easiest material, very small. They are sunk to a depth of 45

to 50 feet below high water, so that their foundation is well below the limit of any scour which

could possibly occur in the future.

Operations Below Low Water Mark

Very great amount of accurate work had to be carried out below low water mar by the aid of

pumps or by divers, and as even the most powerful pumps were unable to control the water

except for a short period at low water of each day during the period of spring tides, the

operations were necessarily prolonged. In fact, many of the portions of the work carried out

have no precedent in engineering operations, in that no benefit was obtainable from prior

experience gained in similar work, and many expedients were tried from time to time by the

contractors to solve the various problems, and great credit is due to them for the manner in which

they have finally overcome all difficulties. It is also a matter for congratulation that, in spite of the

somewhat risky nature of the pneumatic process of forming foundations, especially in tidal

rivers, no fatal accident has occurred since the commencement.

The structure is now quite complete and the sluices in working order, the only thing remaining

to be done being the drawing of old piling and the placing of a new skin of heavy slag all over the

river bed, so as to prevent any scouring action in the future.

Division Of The Weir

The type of weir adopted, as already mentioned, is that patented by the late F.G.M. Stoney

and consists of three large sluice gates 80 feet long by 12 feet deep, each closing up one of

the three 80 feet spans into which the weir is divided. These gates weigh about 45 tons, but

20 tons of counter-balance weight is provided at either end, so that only five ton net lift remains.

The lower edges of these gates, when down for the purpose of damming up the water on the

upstream side, is in very close proximity to a massive granite sill by the caissons formerly

mentioned, but is not closed right down on it, a sufficient space being left so that just enough

water gets away underneath to ensure that the ponded up water on the upstream side shall

remain at a constantly uniform level. When there is a large amount of water in the river these

openings will be increased, and when a small amount, diminished. At high water, or shortly

after it, the gates are shut down and while the tide recedes on the down-stream side as it does

ordinarily on the up-stream side, the water remains at the level it held when the gates were shut

down, thus ponding up the water, and forming practically a long lake extending beyond

Dalmarnock Bridge, and as a consequence preventing that unsightly exhibition of

mud and garbage, and in summer the objectionable smell from decaying matter which

are observed at the present.

Navigation Arrangements

On the incoming tide rising and reaching the level of the ponded-up water on the up-stream

side, the water pressure on the gates is naturally equalised, and the gates are then lifted and

navigation allowed to go on unimpeded as through an ordinary bridge. As the gates rise they are

tilted over into a horizontal position, until the face of the sluice gate is at the same level as the

crown of the arch, and the appearance of an ordinary bridge is obtained. Each gate is raised and

lowered by a small hydraulic engine situated in the centre of each span, and the process of lowering

or lifting a gate takes about three minutes. As a final result of the undertaking, the dilapidation of

the river banks will be stopped and it is confidently expected that when they are restored, the

stretch of river lying to the east of the weir will once more become a boating centre, and with a

purified river, which is not very far distant, will once more prove an attraction to the citizens, and,

instead of being an eyesore, become the scene of much healthy and enjoyable recreation, not

very different from what obtains on the Thames at present.

Engineers and Contractors

It should be mentioned that the engineer in chief for the whole works has been Mr. A. B.

McDonald, M.Inst.C.E., the City Engineer, with Mr. John Cowan, Assoc. M.Inst.C.E., as

resident engineer, while Messrs Ransomes & Rapier (Limited) of Ipswich, have erected all the

steel work of the superstructure, as well as the ‘Stoney’ sluices, the foundations, masonry, and

general work being executed by Messrs. Morrison & Mason (Limited), Polmadie.

Completed Bridge, 1901 

The bridge remained until 1941 when flooding to the surrounding area

occurred - scour undermining the abutment foundations. At this time, both the structure and

the tenements on Adelphi Street on the south bank were demolished.

The present bridge was completed in 1949 and carries pipes across the river.

Bird's Eye View showing Glasgow Green on the north bank.

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