Jubilee Bridge (Queensferry)
A retracting bridge spanning the River Dee at Queensferry, Wales, named in commemoration of Queen Victoria's jubilee. Also called Victoria Bridge, Queensferry.
1895 Work on this unusual 'telescopic' bridge commenced in April 1895. T. W. Barber was chief engineer.
1896 'THE QUEEN'S FERRY BRIDGE. A CHAT WITH THE ENGINEER.
One of our representatives visited Queen's Ferry this week for the purpose of seeing what progress is being made with the new vehicular bridge over the Dee. It was in June last that the work was commenced, and though many difficulties have had to be contended with, it is now rapidly approaching completion. At the outset it may be well to give an idea of the design of the structure. In the centre is an opening of 120 feet, spanned in two halves, each by a rolling girder, projected from the fixed portion of the bridge. The moving apparatus is simple, and will be rapid in action. By an ingenious automatic arrangement, the decking, ironwork, hand-rails of the movable span are made to collapse, and each part is drawn back on the telescopic principle by means of powerful rams, leaving a clear waterway for vessels to pass through. The movement is effected by hydraulic power, and the engineers do not anticipate any trouble through the strong gales which occasionally sweep the lower part of the Dee.
The design of the structure is quite unique. Mr. R. Routledge, the courteous representative of the contractors, the Tees Side Iron and Engine Co., Limited, has had considerable experience in the erection of bridges and piers, and, in course of conversation, he assured our representative that there is not another bridge like it in England. It involves a tremendous amount of mechanical work, but it is admirably designed to meet the general requirements. The fixed portions of the bridge are already in position. The heavy ironwork has all been brought from Middlesborough to Queen's Ferry Station. When it is stated that the portion of the structure erected on the Sealand side alone weighs 120 tons, it will be seen that the work of carting the metal to the river, and carrying it across in barges, has been by no means light. Everything, however, has been safely accomplished. Each fixed span from the abutment to the end measures 130 feet, so that, with a movable span of 120 feet, this gives the total length of the bridge as 380 ft. Questioned as to the completion of the work, Mr. Routledge said : "We have just received the rolling girders for the centre ; they weigh 65 tons, and, given fine weather, we shall have them fixed in about a fortnight. I expect vehicles will be passing over the bridge at the end of May, though in the remaining two months we have a lot of hard work to get through. The vehicular road will be 20ft. wide, and 9ft. in the centre, so that across the movable span only one vehicle can pass at a time. The footpath is 3ft. 6in. wide on either side of the road." In the minds of some people who have no engineering knowledge, doubts seem to be entertained as to the stability and carrying power of the bridge. These doubts, which one always hears in connection with an undertaking of this sort, may easily be set at rest. In the first place, ten screw piles, 3ft. 6ins. in diameter, have been sunk over 20ft. in the sand or rubble, and each has been tested with 30 tons of dead weight, without deflecting the 30th part of an inch. This is more than double the strain the piles will have to bear. The bridge is only designed to carry a traction engine, that is, 20 to 25 tons, and " this," says Mr. Routledge, "it will do during the roughest weather we are likely to experience. The movable span has been tried and tested at our works at Middlesborough, and found to work very satisfactorily. Supposing anything went wrong with the hydraulic machinery, we have the hand power gearing to fall back upon. The whole thing will be controlled by a man in the watch tower on the Queen's Ferry abutment, from which he will be able to command a view in all directions. There will be some code of signalling (probably an electric bell) from the other side, and the man in charge, in order to put the machinery in motion, has simply to open a valve. The bridge will be opened, I expect, every four hours. The fixed portions of the structure are protected from damage by passing vessels by timber fendering driven down 22ft. into the bed of the river." The approaches to the bridge are now practically finished, the contractors for the masonry work being Schofield and Sons, of Leeds. The bridge will be a wonderful improvement on the existing mediaeval ferry, and its opening for traffic at the end of May next is eagerly awaited by farmers and tradesmen on both sides of the river. No doubt there will be a formal opening ceremony, and probably the button that controls the mechanism of the structure will, as in the case of the adjoining Hawarden railway bridge, be pressed for the first time by the " Old Parliamentary Hand." '[1]
April 1897 bridge was completed and the public allowed free passage across.
The bridge was officially opened on 2nd June 1897 by William Gladstone.
Description from Engineering 1897/06/11
'Telescopic' bridges are such a rarity that it is considered worthwhile to reproduce part of the description and some of the drawings from Engineering, even though these do not provide sufficient information to clarify the mechanical arrangements.
In essence, there are two movable spans which withdraw into the fixed spans. Six large wheels support each movable span. The initial withdrawal movement causes the decks of the moving spans to drop by 15 inches (the deck being supported by hinged struts from the main moving span structure). At the same time the hinged handrails are dropped. The movement is provided by hydraulic rams acting on cables.
'The method of working the movable centre span is somewhat novel. It is made in two halves, each 60ft. long, which travel in and out of the fixed spans, meeting in the centre of the river. To admit of this motion the platform is deflected downwards a distance of 15 in. to pass underneath the platform of the fixed spans. The motion is derived by means of a cam roller working in a cast-iron roller path. This is very clearly shown in Fig. 8, the dotted lines marking the position of the roller and platform when the bridge is closed and the platform raised. The handrailing is also collapsible, folding down level with the roadway, as shown in Figs. 6 and 8. The movable half-spans are formed of two main lattice girders braced together transversely. The platform is carried by 11 cross-shafts with vertical swinging arms; its motion being the arc of a circle, the centre of which is any one of the 11 cross-shafts. It is balanced by a heavy box of pig iron which is suspended by four swinging vertical levers, enabling it to move through the same arc of a circle as the platform. The movable girders are carried on six cast-iron flanged wheels 4 ft. 4 in. in diameter, the motion being imparted by a couple of hydraulic rams working a steel wire rope.
'The arrangement will best be understood by referring
to Fig. 4, where the movable span is shown in the
position it occupies when the bridge is open. Practically the whole thing may be considered as a balanced
lever, the fulcrum being situated at the point marked
A, Fig. 4. The hydraulic rams, 8 in. in diameter by 11 ft. 6 in.
stroke, are attached in a horizontal position to the
cross-girders of the fixed spans. The pressure at
750 lb. per square inch is supplied through an
accumulator by a pair of Pearn's vertical duplex
steam pumps ; steam cylinders 8 in. by 6 in., pumps
2 in. and 2! in. in diameter by 6 in. stroke. All
the hydraulic machinery is in duplicate, and has
been supplied by Messrs.F. Pearn and Co., Manchester.
The accumulator-house is of white Aston Hall
bricks, and is situated on the Flint abutment.
A watch-room is provided at the top of this house,
giving a commanding view of the bridge itself and of
tho river up and down stream. It will be understood
that the water power has to be conveyed across the
river for the purpose of working the opposite span.
Great difficulty has been encountered in keeping these
pressure pipes tight. The River Dee (unlike its
neighbour, the Mersey) is subject to the tidal phenomenon commonly known as a "bore." At the turn of
the tide a wave is seen advancing up the river at a
speed of four or five miles an hour; it is usually of a
convex form, and varies in height from 2 ft. to 4 ft. This exercises a scouring effect on the river, and at
times completely alters the character of its bed. A
striking instanoe of this unfortunately occurred quite
recently at Queensferry. A very considerable leakage
took place quite suddenly in the pressure pipes, and it
was thought one of the joints must have blown; on
taking soundings it was discovered that the bottom
had been scooped out into two hollows 3ft. and 7ft.
below the normal bed of the river, the result being
that the pipes were suspended clear of the bottom for
a distance of 130 ft. with a single point of support
about halfway; to be accurate, the hollows were 50ft.
and 80ft. wide respectively. The pipes now in use
are of copper 1 1/2 in. in internal diameter, jointed with
screwed unions; it is in contemplation to try solid-drawn· lead pipes bound externally with copper wire. .....
'....The whole of the steel and iron work of the bridge has been carried out by the Teesside Bridge and Engineering Company of Middlesbrough and the stonework approaches, &c., by J. Schofield and Sons, of Leeds. The total cost was 14,000l., which sum has been contributed partly by the Flint County Council, who undertake the management and working of the bridge, and partly by subscriptions from the Cheshire County Council and the Hawarden estate trustees.'
Note: T. W. Barber of 17 and 18 Tothill-street, Westminster, wrote to Engineering stating that solid drawn lead ppe, covered with close coils of copper wire, had been laid and worked very successfully, [2]
1926 Having proved inadequate for the volume and weight of modern traffic, the bridge was replaced by a double leaf rolling bascule bridge, also called the Jubilee Bridge (also known as the Blue Bridge) - see Queensferry Bridge.
By the 1960s shipping had ceased on the River Dee. The bridge's lifting mechanism was removed and the roadway fixed permanently in place. ________ The 1909-11 O.S. map here identifies the bridge as 'Victoria Jubilee Bridge (Telescopic Action - Toll)'. A short distance to the south east were landing stages, a shipbuilding and engineering works, the Queensferry Chemical Works, and the sidings of the Aston Hall Colliery Railway.
See Also
Sources of Information
- ↑ Cheshire Observer - Saturday 21 March 1896
- ↑ Engineering 1897/06/18
- Wikipedia [1]