1927 Public Works Department Annual Report
Sydney Harbour Bridge Branch.
Report for the year ended 30th June, 1927.
I have the honor to submit the following report on the work of this Branch for the year ending 30th June, 1927: —
1. CONSTRUCTION OF THE NORTHERN APPROACH.
(a) Tunnels.
The double track tunnel for the Up and Down Shore tracks, which bifurcates near North Sydney Station, was excavated and lined with concrete with the exception of the side drains.
The single track tunnel from North Sydney for the Down Shore Local was completed, and the offtake for the Down Mosman flyover was excavated and the side walls concreted.
The portal near Bank-street for the pair of double track tunnels was completed, and a granite block dated “ 1927 “ placed in position.
During the year 13,911 cubic yards of rock were excavated, and 6,807 cubic yards of concrete placed in position.
The flyover section of the offtake for the Down Mosman tunnel was cleared to the roof of the Up and Down Shore Local tunnel and concrete, heavily reinforced, placed in position.
The construction to the Western End of North Sydney station is now practically complete.
(b) Open Cut Excavation.
Excavations in open cut were made from Miller-street to Fitzroy-street: the heaviest sections being the cutting from Walker-street to Little Walker-street, deviation of Arthur-street, abutments for Arthur-street Arch, retaining walls near Arthur-street, and the retaining wall from McDougall-Street to Burton-street.
The quantity of open cut excavation during the last twelve months amounted to 20,080 cubic yards.
(c) Concrete Work.'
The retaining wall from McDougall-street to Burton-8treet, with the exception of one panel, has been completed, also the stairways near the site of Kirribilli Station. This wall is approximately a quarter of a mile long and its completion wilt enable a new road to be constructed from Broughton-street to Junction-street, which it is anticipated will be opened for traffic in 1928. This road will then allow all the vehicular traffic from Jeffrey-street to be routed direct to Junction-street, and will permit of easier construction of the bridges to be built near Alfred-street.
The abutments of the Arthur-street Arch were partly concreted.
The total quantity of concrete placed in position, including incidental works such as sumps, drains, causeways, piers, &c., amounted to 4,269 cubic yards.
The total quantity of concrete placed in position for the Northern Approach. including the tunnels, during the year amounted to 11,076 cubic yards, requiring 33,687 bags of cement. The aggregate used for the greater proportion of this concrete was crushed selected sandstone from the tunnels; the sand being a mixture of crushed sandstone and Nepean sand.
(d) Alteration to Existing Service.
Water mains and gas mains were cut and capped at Willoughby, Arthur and Walker streets. Telephone lines were removed from Milson and Little Walker streets. Electric underground cables were removed from Arthur and Willoughby streets. Overhead power lines were removed from Willoughby-street to McDougall-street. Electric light poles were removed from Willoughby, Milson, Walker and McDougall
streets, and where possible placed on their future alignments.
(e) Resumptions and Demolition of Property.
Properties to the number of 178 and also old walls, racks, sheds, &c., were disposed of by auction, the gross receipts being £5,459 2s. 3d.
At the end of March Messrs. Dorman, Long & Co. were given possession of the remainder of the land required for the purposes of their contract at Milson's Point.
The total amount paid for land resumption, including the Southern Approach, together with compensation, is as under: —
To 30th June, 1926 £365,330 12 0
1st July, 1926. to 30th June, 1927 £278,799 7 2
Total £644,129 19 2
(f) General.
There were a large number of incidental works carried out in connection with the Construction of the Northern Approach, such as storage bins for sand and crushed stone, construction of cement storage shed with unloading platforms and lorry dock, erection of office at Dorman, Long and Co.'s workshop for the steelwork inspectors, building carpenters’ sheds and stores. Fixings for the electrification of the North Shore line to the Bank-street bridge, and in the tunnels, are now almost complete.
The average number of men employed was 160. Although a difficulty has been experienced in obtaining vacant possession of resumed property as required, satisfactory progress has been made with the construction of the Northern Approach.
2. CONTRACT OF DORMAN, LONG & Co.
(a) Excavation, Concrete and Masonry.
During the year the Approach Span Piers have been completed, with the exception of Piers Nos. 17 and 18 of the Northern Approach, and good progress made with the Southern abutment tower.
The coal strike in England delayed the arrival of steel plates, and the original programme for the construction of the Approach Span Piers had to be varied. The original intention was to build each pair of piers after the falsework had been erected up to the site of the piers, but as this would have ultimately delayed the erection of the steelwork whilst the Piers were being completed. Piers Nos. 5, 6, 7, and 8 on the Southern side and 15, 16, 17, and 18 on the Northern side were erected by using a special crane for each set of Piers.
The excavations for the skewbacks and the abutment tower at Dawes Point had been completed last year and a commencement made to place concrete in the skewbacks. This has now been completed and the walls of the tower built to R.L +54. The granite masonry of the walls commences at R.L. +7 5 and up to R.L. +27.5 the granite was set and the concrete placed behind. Above the latter level this method of construction was modified as Moruya Quarry could not supply the granite facing in sufficient quantities to keep pace with the concreting. The concrete walls of the tower are carried up as a shell 3 feet 6 inches thick with steel reinforcement. The masonry was set in position as it arrived, and the space between the masonry facing and the concrete shell walls filled with concrete. At the end of June, 1927, the masonry facing had been built to R.L. +38. To protect the apron stones from damage they have been covered with sandbags which will remain in position until the completion of the abutment tower.
During the year one of the most critical phases of the construction of the Bridge was completed, viz., the erection and concreting in position of the two main bearings at Dawes Point. Each of those bearings weighs 296 tons. They were assembled in sections on specially built cradles. The erection of the South-east bearing commenced on 25th March, 1927, and the steelwork was completely erected on 23rd April with the placing of the upper saddle. The erection of the south-west main bearing was commenced on 9th May and was completed ready for concreting on 20th May.
All sections of the bearings had been most accurately machined and came together with a perfect fit. After erection, the bearing was supported by hydraulic jacks at the four corners and brought in to correct alignment to 1/64"by instruments mounted on a concrete tower, specially constructed for the purpose, at the intersection of the centre line of the Bridge and the centre line of the main arch pins. The next stage was to concrete under the bearing. Heavy reinforcement was placed in position, also special devices to prevent any movement of the bearing should the jack slip, the jacks being fitted with screw collars on the rams to lock them at any required position of the stroke. The concrete was placed in one continuous pour of fifteen hours for the first bearing and fourteen hours for the second. The quantity of special concrete under each bearing is 157 cubic yards, and is a mix of special cement supplied by the Kandos Cement Co., Nepean River sand and graded crushed granite, the proportions being 1 cement, ¾ Nepean sand and 2¼ granite aggregate. Field tests of this concrete show a high crushing strength, at twenty-eight days varying from 5,700 to 7,000 lb. per square inch.
At Milson's Point owing to the scarcity of aggregate the only work done on the abutment tower was to concrete the walls at the south-west corner and the skewbacks to within a foot of the finished level.
The following quantities show the amount of Civil Engineering carried out during the year: —
cub. yds.
Earth excavation 29
Rock excavation 3,189
No. 1 concrete 34,115
No. 2 concrete 4,324
Granite masonry 3,783
(b) Fabrication, of Steelwork.
During the year there were 6,193 tons of carbon steel delivered to the workshops at Milson's Point, 3,643 tons coming from Middlesborough, England, and 2,550 tons from the Broken Hill Proprietary Co's. Works at Newcastle. The steel deliveries were considerably affected by the coal strike in England and fabrication was thereby delayed.
The rivets are being made by Messrs. McPherson's Pty. Ltd. of Melbourne, contracts having been placed by Messrs. Dorman , Long & Co for 1,000 tons.
The first consignment of shop paint was delivered in June, 1926, and to the end of June, 1927, 2,315 gallons have been delivered. The paint is manufactured by Messrs. Lewis Berger Ltd., Rhodes, Sydney.
The total weight of material fabricated in the shops during the year was 4,914 tons, with 612 tons in February and in June of this year as the highest monthly output.
The graph herewith shows the quantities of material delivered, fabricated, erected in place and completely riveted in place since the first steel delivery.
The first shop rivet was driven on the 12th June, 1926.
(c) Erection of Steelwork.
Falsework for Spans Nos. 1 and 2 at Dawes Point and Span No. 6 at Milson's Point had been placed in position previous to July, 1926, but owing to non-delivery of plates from England it was not until 28th October, 1926, that the first steelwork was placed in position for Span No. 1.
On the 30th June, 1927, Spans Nos. 1 and 2 were completely erected with the exception of some of the light deck material and Span No. 3 was nearing completion. The erection of Span No. 6 on the Northern side was commenced on 16th June, 1927, one panel being completed as shown in the photograph.
The falsework has been removed from under Span No. 1; the fences removed from George-street North and York-street and the roadway and footpath surfaces repaired. The falsework from Span No. 1 was used for Span No. 3 and the falsework being removed from Span No. 2 is being re-erected for Span No. 4.
To place in position the light deck steelwork, an electric derrick crane previously used to construct the piers, has been erected on the roadway troughing of Span No. 2; a similar method will be adopted at Milson's Point.
To enable the final tint of the finishing coat of paint for the steelwork to be determined, six sheets of steel were painted with the shop paint and first field coat and then finishing coats tinted differently were applied to the various sheets. These were painted in August. 1926, and will remain exposed to the weather until it is necessary to make the selection of colour for the finishing coat. The paint will be as specified when tenders were called in 1923.
(d) Moruya Quarry.
During the year a new crusher has been installed to take blocks of granite 36 inches by 42 inches and this has considerably improved the output of concrete aggregate; two of the freighters, however, are still adequate to cope with the carriage of material from Moruya to Sydney.
In March, 1927, Sir Bertram Mackennal arranged for Dorman, Long & Co., to carry out the construction of the granite pedestal for the Anzac Memorial to be erected in Martin Place. At the request of Sir Bertram Mackennal, with the concurrence of the Minister for Works, I arranged for the stonework and supervised its erection. There are twenty-three stones in the granite pedestal and every care was taken to assure that any black and white markings in the granite would be inconspicuous.
(3) CONSTRUCTION OF THE SOUTHERN APPROACH.
The construction of the Southern Approach commenced on the 6th October, 1926. The major portion of the Work has been confined to excavation between Grosvenor and Margaret streets, but up to date this has been slow on account of operations being hampered by the delay in deviating under-ground services and the time taken to demolish Scots Church and the St. Phillip's Church Schoolroom.
(a) Excavation.
The excavation so far is chiefly the open cut excavation between Grosvenor-street and Margaret-street; in addition there were trenches for water and gas mains, telephone and electric cables, deviation of Margaret-lane, foundations for compressors, &c. The total quantity of excavation from the commencement of operations in October, 1926, to 30th June, 1927, amounted to 13,113 cubic yards.
(b) Concrete Work.
The concreting for the Southern Approach has been as yet confined to minor works and amounts to only 100 cubic yards in all.
(c) Alterations to Existing Services.
A 12 inch water main was deviated from York-street and a 6 inch main from Margaret-lane.
Telephone cables were deviated in York-street and electric mains were deviated between Grosvenor-street and Margaret-street.
Other service removals include street lights, taxi-phone box and drinking fountain. In all the above cases the excavation and backfilling were carried out by this Branch.
(d) Resumption and Demolition of Property.
During the year 107 properties have been sold for demolition, the gross proceeds amounting to £1,605 12s. 6d. In December, 1926, the Scots Church, erected over one hundred years ago, was sold and has since been demolished.
(e) Tunnels.
The four single-track tunnels under Margaret-street from Wynyard Station have been carried out by the Metropolitan Railway Construction Branch and are now almost completed.
The Up Shore Local and the Down Shore Local were excavated and completely concreted for a length of 60 feet. The Up Shore and the Down Shore were excavated and are now almost completely concreted for a distance of approximately 180 feet.
The work as carried out comprised 5,581 cubic yards of excavation, 1,005 cubic yards of concrete lining and 87 lineal yards of roadbed.
(f) General.
As on the northern side of the Harbour difficulty has been experienced in obtaining possession of the properties when required, but vacation of property is now proceeding satisfactorily. The average number of men employed since the comencement of operations has been 50. In addition to the work mentioned above, there has been a considerable amount of preliminary work such as fencing (approximately 1,250 lineal feet), the building of compressor sheds and the installation of compressors, cooling towers, circulating pumps and air receivers, and the erection of a smith's shop and magazines.
(4) FINANCIAL REVIEW.
(a) Land Tax.
To defray one third of the capital cost of the Land Resumptions and Construction of the Bridge and Approaches, a land tax of one half-penny in the pound has been imposed on the Unimproved Capital Value of all land situated within the city of Sydney, the Municipalities of North Sydney, Mosman, Manly, Lane Cove, and Willoughby, the Shires of Warringah and Kuring-gai and portion of the Shire of Hornsby.
The tax was first imposed in the year 1923; the rates due for the years 1923-27 are as shown in table below. Of this amount up to 30th June, 1927, £542,492 19s. 11d . was paid to the Special Deposit Fund, leaving a balance of £175,158 11s 8d. to be paid before 3lst December, 1927.
The table shows the details of the rales due since the tax was first imposed, the payments to 30th June, 1927, and the balance outstanding at 30th June, 1927,
(b) Expenditure.
The total expenditure up to .30th June, 1927, is shown in the following table. It is seen that on Dorman Long & Co's., contract for the main bridge and steel approach spans the wages variation to date is slightly less than 9 per cent, of the total amount paid for construction. The total cost of the Bridge and Approaches to date, including all expenditure prior to 1st July, 1923, is £1,852,240 18s. 2d,
(5) CONCRETE TESTS.
Further long-date tests of concrete cubes for special granite concrete were carried out as under: —
As a result of the above tests it was decided to use the 1: 1¼ : 3 mix for special concrete No. 2, forming
the second layer of concrete beneath the main bearings, that is, below the special concrete No. 1.
Special Concrete No. 1.
For the layer of concrete directly beneath the main bearings a further series of cubes of a rich mix were tested. The results of tests are as under: —
This concrete was made with special high-strength cement, giving a compression strength in 3 : 1 mortar at twenty-eight days combined air and water hardening of over 7,000 lb. per square inch, and the high strength achieved ensures a factor of safety of at least ten against the thrust from the main arches applied at the bases of the bearings. Field cubes taken from the concrete poured to date on testing give practically the same results.
(6) STREET WIDENING AND EXTENSIONS.
In May last at the request of the Premier I was authorised to report upon the practicability of extending Martin Place westward from George-street to York-street and the widening of York-street from Wynyard-street to Druitt-street: the widening of York-street from Grosvenor-street to Wynyard-street is being carried out under the Bridge Act.
Various schemes were investigated in detail from the point of view of traffic facilities and finance. I recommended the extension of Martin Place from George-street to York-street and the widening York-street from Wynyard-street to Druitt-street.
Subsequently Cabinet decided not to extend Martin Place but to widen York-street from Wynyard-street to Druitt-street to 81 feet, thus providing a widened York-street from the Bridge Crescent near Grosvenor-street to the Town Hall.
(7) STAFF.
The number of men directly employed on the bridge and approaches as at 30th June, 1927, was approximately 1,250. Dorman, Long & Co. employed 250 at Moruya, while over 700 are employed at Sydney in the workshops, placing concrete and masonry and erecting steelwork. The Sydney Harbour Bridge Branch of the Public Works Department now has over 300 men on the approaches, and arrangements are being made to augment this number.
I desire to place on record my appreciation of the work of the staff during the past year.
J. J. C. BRADFIELD.
Chief Engineer, Sydney Harbour Bridge.
