The King Edward VII Bridge, Newcastle-On-Tyne.” by FRANKWILLIAM DAVIS and CYRILREGINALD SUTTON KIRK- PATRICK, Assoc
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158 DAVIS AND KIRKPATRICK OK THE [MinuWs of (Paper No. 3742.) ‘‘ The King Edward VII Bridge, Newcastle-on-Tyne.” By FRANKWILLIAM DAVIS and CYRILREGINALD SUTTON KIRK- PATRICK, Assoc. MM. Inst. C.E. THEmain line of the North Eastern Railway is carried across the River Tyne bp what is known as the Old High-Level Bridge. The people of Newcastle are justly proud of this picturesque structure, and also of theengineers who designedand constructed it, Messrs. Robert Stephenson and T. E. Harrison, Past-Presidents of TheInstitution. The bridge was formallyopened on the 15th August, ,1849, by the late Queen Victoria, amidst general rejoicings, for besides being the first railway-bridge over the Tyne, it was also the first high-level road-bridge connecting the Cityof Newcastle with Gateshead. The bridge was constructed for three lines of railway, and for nearly 60 years the whole of the enormous traffic of the districthad to be workedover thesethree lines. As thetrafic continued to increase, the directors of the North Eastern Ra,ilway Company decided toconstruct a newhigh-level bridge with four lines of railway, and parliamentarypowers for this undertaking were obtained in 1899. The position decided upon for the new bridge was 710 yards west of the old structure,and 260 yardseast of the Redheughroad- bridge (Fig.l). This position was chosen so that trains from London could enter the Central Station at one end and proceed northward fromthe opposite end, thus doing away with the objectionable arrangement previously existing, whereby trains had to enter and depzrt at thesame end of the station. The new bridge,now known as the King EdwardVI1 Bridge, was designed by Dr. Charles Ezrrison, M. Inst. C.E., Engineer to the Downloaded by [ La Trobe University] on [02/10/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] KING EDWARD VI1 BILIDGE, XERCASTLE. 159 Northern Division of the North Eastern Railway, and it carries the railwayonly, without any accommodation for vehicles or foot- passengers.The contra.ct for the whole of theworks was let,on the6th March, 1902, tothe Cleveland Bridge and Engineering Company, of Darlington. Leaving the west end of the Central Station the railway bends to \ JESMOND NEWCASTLE NEW BRlDGE S? ST” REDHEUGH BRIM Scale: I Inch - 4,000 Feet. FEET !3,000 tDa0 3,000 %p00 ,p00 0 5.000 FEET the south on a curve of 10 chains radius, and crosses the river in rz straight line (Fig. 2, Plate 4). On the south side of the river four lines diverge on a 10-chain curve to the west, and join the existing Team Valley line, nearthe point whereit is crossed by the Redheugh Road, and two lines turn on a 7-chain curve to the east and join the Team Valley line near Gateshead statiob. A saving in distance of 682 yards is effected by the new route. The cost of the bridge and Downloaded by [ La Trobe University] on [02/10/16]. Copyright © ICE Publishing, all rights reserved. 160 DAVIS ASD KIILKPATRICK ON THE [Xinuteu of approaches,exclusive of landand permanent way,was about g500,OOO. For the purpose of this description the work will be divided into six sections, namely- I. The Foundations. 11. The Korth Approach. 111. The Superstructure and its Erection. IV. The South Approach. V. The Cableway. VI. The Board-of-Trade Inspection and the Opening. THE FOUNDATIONS. The contractors’ experience with electrical driving on other works having been very successful, it was decided to drive the plant used in the construction of this bridge as far as possible by electricity ; and in order to avoid any danger of breakdown while sinking the caissons, the generating-plant was duplicated. A generating-station was built on the Gateshead sideof the river, at the top of the bank, and sidings were laid down from a junction with the main line. The plant consisted of foursemi-portable boilers of locomotive type, any two of which were capable of providing sufficient steam, at a pressure of l50 lbs. per square inch, to work the whole of the machinery. The generating-plant consisted of two sets of enclose- high-speed compound engines coupled direct to multipolar dynamos, each set beingcapable of giving an outputof 740 amperes at 240 volts, or about 240 HP. There were also three smaller sets for lighting at 110 volts. The main switchboard was arranged so that the two large sets couldbe used in parallel, if required. An electricity-meter, reading Board-of-Trade units, was placed on the main circuit, ancl also a recording ampere-meter reading up to 1,200 amperes. For supplyingcompressed-air tothe caissons three horizont,al compressors, havingcylinders 15 inches in diameter by 36 inches stroke, driven through steel spur-gearing by 125-HP. shunt multi- polarmotors, were laid down close tothe river. Each engine delivered about 740 cubic feet of free air per minute when running at 100 revolutions, and by means of a regulating resistance on the shunt-circuit of the motors, the speedcould beincreased to 110 revolutionsper minute. The air-cylinders had water-jackets for cooling, and a high-flash lubricating-oil was used, in order to keep the air as pure as possible. The valves were operated by Corliss gear and had a positive action, and were also governed by a compressed air piston which controlled the air-pressure as required within 5 lb. Downloaded by [ La Trobe University] on [02/10/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] KING EDWhllD VI1 BRIDGE, BEWCASTLE. 161 The caissons (Figs. 3 and 4, Plate 4) wereconstructed of mild steel, the thickness of the outer plates of the shell ranging from inchto 4 inch.The area of allthree caissons was the same, namely, 3,361 square feet over the outside of the cutting edge ; but the height of the permanent part varied according to the level of the river-bed, the south caisson being 54 feet, the centre caisson 26 feet 6 inches, and the northcaisson 56 feet high. The total depth of the temporary and permanent caisson together was about 75 feet in all three cases. Thetemporary caisson was joinedto the per- manent by a bolted joint, so that it could be disconnected by divers at about the level of the bed of the river. The cutting edge of the caisson, as shownin Fig. 4, was formed of threethicknesses of plate,the outermost being 6 inch thick. The shoe, which was carriedcontinuously round the caisson, was stiffenedby plate diaphragmsinch thick, 3 feetapart between centres,braced withangle-bars, theinner skin of the shoebeing composed of onethickness of plate, andthe outer skin of twothicknesses. The angle-bar at the bottom of the shoe was designed to act as a brake to the caisson during its descent through soft ground, and, together with the two wide-flanged girders, it proved to be of con- siderable assistance in keeping the caisson level. It will be noticed (Fig. 4) that the roof of the working-chamber was curved and had a headroom of 9 feet 6 inches at the highest point and 8 feet at the lowest. This was originally designed to be flat, with 7 feet headroom, but was altered by Dr. Harrison on the Authors’ suggestion. The object of the curved roof is to give more headroom to the men as they advance into the shaft, and also to make it easierto pack the concretetight against the roof when fillingup theworking-chamber. Subsequent experience during the progress of the workproved thealteration in the headroom to havebeen necessary, the cutting edge insoft ground being frequentlyconsiderably ahead of the digging.Another important addition to the caisson was made in putting the two large girders across the working-chamber between the shafts with wide bottom flanges 3 feet 6 inchesabove thecutting edge. Themain object of thesegirders was toprotect the men in case of soft ground being encountered which might cause the caisson to sink rapidly ; in this case the wide flanges would come in contact with theground and prevent further sinking. They were also very useful in keeping the caisson plumb and regulating its descent. At all times during the excavation a bank was left underneath each girder, and at high water,:when, owing to the increased air-pressure, theweight of the caisson was least, the tops of the bankswere [THE INST. C.E. VOL. CLSSIV.] M Downloaded by [ La Trobe University] on [02/10/16]. Copyright © ICE Publishing, all rights reserved. 162 DAVZS AND KIRKPATRICK ON THE [Minutes of removed until there was about 9 inches clear between them and the bottom of the girders ; then as the tide wentback the caisson would graduallysink until it restedagain onthe banks. These large girders are shown by dotted lines (Fig. 4). Immediately above the working-chamber the caisson is spanned by girders 3 feet 6 inchesdeep and 3 feetapart. These c'arry the ceiling-plates and also form the floor upon which the weight of the concreterests during the process of sinking.The flooring was designed to carry a load of 1 ton per square foot distributed overthe whole area. The ceiling-plates of the working-chamber formed the bottom flanges of these girders and were 22 inch thick. Above the top of the shoe the skin was one plate thick only, but above the tops of the flooring-girders it was stiffened by rolled joists 8 inchesdeep and 3 feetbetween centres placed vertically.This, portion of the caisson was further stiffened by two belts, running continuously round it, formed of girders about 2 feet deep, m shown in section in Fig. 4, ancl braced by light lattice-girders and diagonally by channel-bars.