North Gate Bridge, Cork

DEMOLISHED IN 1961. Replaced by Griffith's Bridge.

Architect: Sir John Benson.

See here for illustrations

1864 'NORTH GATE BRIDGE.
The new bridge at North Gate which was opened yesterday morning at nine o'clock by the Mayor, accompanied by a few civic officials, is another important addition to the public structures which have of recent years begun to ornament this city. Those who remember the old hump-backed bridge which till a year ago stood in this spot must be gratified by the sight of the handsome and elegant structure which now occupies its place; and if the much more important elements of strength and security be regarded the advantage of the new work over the old must be still more impressive. The thoroughfares which the bridge connects, joining it may be said the entire North of the city, with one the busiest and most populous parts of its centre, rendered it desirable that the bridge in that place should offer every facility to traffic, while of a secure and substantial character. Every one acquainted with the city knows that the old North Gate bridge was exactly the reverse of this, from the enormous gradients on it, its narrowness and its utter unsuitability — so much doubted previous to its being pulled down, but so fully proved in doing so. On the removal the south abutment of the old bridge, which was built on mud and gravel, it was found to be three inches out of plumb, and had sunk several inches, which caused a fracture in the crown of the arch the whole length, and also in the wing arches. The latter the contractor wss obliged to allow to fall into the river when shoaring, they were so damaged. The pier adjoining those angles was in a dangerous state, being merely faced with limestone eight inches thick, the centre being dry rubble. The north arch also sank in the crown about ten inches.
The new bridge offers a remarkable contrast to this. That in the first place it meets every requirement of the locality every one who sees must admit; its handsome proportions and graceful span give an improved appearance to the entire neighbourhood; whilst the stability of its structure may be gathered from the following facts: The new foundations are 80 feet long, 12 feet broad, and are sunk five feet below low water level. In the carrying out of this portion of the work, owing to the close proximity of the buildings adjoining, piles 21 feet long, and six feet apart, had to be driven back of the abutments to sustain the bank, shooted inside with three-inch planks and braced from the river bed. Tidal dams were found to enable the excavation to be made, and a steam engine and centrifugal pumps capable of raising 1,100 gallons of water per minute, had also to be employed to keep the water down while the excavation was being made, and the foundations laid.
The new foundations consist of two feet of cement concrete, on this is laid blocks of stone six feet six inches in length, four feet in depth and two feet width, stones three feet six inches long are placed between these and the cells, and the space back of this course is filled with concrete to the level of top stone. A course of two feet thick of limestone is laid on this course the full breadth of abutment. On each abutment eight sets of corbal stones 8 feet long, 2 feet 6 inches deep and 2 feet thick, are set, which receive the cast iron ribs. The difficulty experienced at the south was not encountered at the north side, where a rock four feet under the old foundation was met with, and upon which the entire abutment was constructed. Both abutments and the short pieces of quayage at either side of the bridge bave been built in the most substantial manner.
Messrs. Rankin and Co., Liverpool, were the contractors for the iron arch, and have succeeded in turning out bridge of light and graceful proportions, and one that will constitute a lasting ornament to the city. Eight large cast iron ribs secure the road and pathways ; they are made of the very best material, and are of immense strength. Each rib consists of six parts, all of cast iron, and each part forms well a portion of the arch as of that part upon which the roadway is to be carried, thus securing great strength to the bridge. The span of the arch is 106 feet in the clear, which is equal to the width of the river at that spot, that no obstruction to the flow of the tide is in the slightest degree offered by it. The arch portion of the ribs is two feet six inches deep and two inches thick, with broad flanges at either end ten inches in width, rounded off and forming the moulding, which are carried through the entire line of the arch. The ribs are secured into the masonwork by being carefully bedded upon large masses of stone nine feet in length, two feet six inches depth, and two feet thick ; and between the stone and the iron, thin sheets of lead are placed for the purpose of correcting any inequalities that may arise from the pressure of the two harder materials. The arch is secured in a most permanent manner, the ribs being securely bolted and bound to each other by cast and wrought iron of the very best description.
The roadway is carried upon cast iron plates, which are strengthened in the back by what are called rib flanges; the plates rest upon a continuous flange or bearing cast upon the upper side of each portion of the arch and eight inches below the level of the metalling of te roadway. The whole of this platform of iron covered with asphalte, over which is laid a bed of concrete, bringing the surface to a uniform level, and upon this is placed the ordinary metalling of the road. The pathways sre flagged with granite similar to that used on St. Patrick's Bridge, the flagways being wide, affording ample facilities for the large foot passenger traffic that will pass over the bridge. The external ribs of the bridge are ornamented with mouldings that define the outline of the arch, and also with moulded and fluted cornices, from which spring the hand-rails. These, too, are of an ornamental nature, displaying work of very elaborate design. The railings after passing across the arch form graceful curves at each side and extend on the quays for a distance of about twelve feet, where they terminate in handsome cut stone pedestals, on which will be the inscription for the bridge and the date of its erection. On the centre of the balustrade stand two ornamental lamp posts, and similar ones on the cut stone pedestals. In the spandrills of the up-and-down elevation of the arch are cast iron flanges. On the western flange — or that facing the direction of Sunday's Well — are medallions with busts of the Queen and Prince Consort; while on the eastern flange — or that facing the direction Patrick's Bridge — are medallions with busts of O'Connell and Moore. The four are admirably executed.
The width of the roadway of the bridge is 24 feet, and the two footpaths are 8 feet wide, giving an entire width of 40 feet. The structure is almost level, the incline on it being only 1 in 20, while on the old bridge it was 1 in 7. The design for the new bridge was furnished by Sir John Benson, under whose supervision the work was carried out, and to whom much credit is due for the architectural skill of the design, and the careful superintendence he maintained over the work throughout. The work itself was executed by Mr. Barry M'Mullen who went through his task with an energy, care and workmanlike ability of the highest order. It is only eleven months since the removal of the old bridge was commenced and it is altogether owing to Mr. M'Mullen's hard working energy that the completion of the new one has soon and satisfactorily been brought about. Mr. M'Mullen maintained constant personal supervision over the work, and it to this fact that the care and elaboration displayed in the preparation of the foundations and the building of abutments is mainly due.
The opening of the bridge though formal, was utterly devoid of ceremony. The Mayor merely removed the board erected at one end, and having passed over the bridge, declared it open for traffic, which concluded the proceeding.'

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