1929 Public Works Department Annual Report.
Sydney Harbour Bridge Branch.
Report for the year ended 30th June, 1929.
I have the honor to submit the following report on the work of this Branch for the year ended 30th June, l929: —
I. — CONSTRUCTION OF THE NORTHERN APPROACH BY THE SYDNEY HARBOUR BRIDGE BRANCH.
(a) Excavation.
The excavation, 17,176 cubic yards, was carried out at various places between Fitzroy-street and Walker-street.
(b) Concrete Work.
The concrete poured during the year was 17,046 cubic yards.
The two largest works were the Burton-street arch and the arch of 120 feet span near Lavender-Street.
The Burton-street arch ring, containing 2,014 cubic yards, was poured in eight working days.
The complete arch ring of the 120 feet arch, containing 488 cubic yards, was poured in one day.
(c) General.
In addition to the above major items there was a considerable amount of general work. Careful hand packing was done between the retaining walls and over the rings of the filled spandrel arches, the total quantity being 5,821 cubic yards.
A total of 1,708 lineal feet of permanent and temporary fencing was erected.
The reinforced concrete arch bridges over Arthur-street, Burton-street and Fitzroy-street were waterproofed with bituminous sheeting. This work was carried out by the Ormonoid Roofing Co. by contract, the total quantity being 5,948 square yards.
Concrete kerbs and gutters were poured in Arthur-street, Burton-street, Broughton-street, and adjoining streets. The total length of kerb and gutter poured was 2.943 lineal feet.
In connection with the kerbing and guttering and draining behind the retaining walls and arches,a total length of 648 lineal feet of drains and box drains was laid.
The road surfaces and footpaths of Arthur, Burton and Broughton streets were ballasted and metalled, and the surfacing completed by the North Sydney Council. The total area thus prepared was 5,135 square yards.
The stairways from the footways across the Bridge were completed, the stairway treads and landings were finished with carborundum rendering.
Walls and arches of a total area of 9,727 square yards were cement rendered.
he maximum number of men employed by the Sydney Harbour Bridge Branch on the Northern Approach was 268,. minimum number 168, and the average throughout the year 221.
II. — CONTRACT OF DORMAN, LONG & Co., LTD.
(a) Concrete and Masonry.
During the year the substructure work has been concentrated chiefly on the construction of the two abutment towers at Milson's Point and Dawes Point to the main deck level and on the cable anchorages for the arch.
Span No. 10, the last of the approach spans, was completed. It was erected on timber trestles from 80 to 95 feet in height. The back section of the abutment tower was constructed in advance of the front and sides, so that the bearings for Span No. 10 could be set. This was done in July, 1928, and the false-work was removed by November.
The general level of the concrete shell walls of the Milson's Point abutment tower in June, 1928, was approximately R.L. 90; these were continued during the year to R.L. 155.50 and the heavy reinforced concrete slabs placed over the side cells.
The masonry facing of the Milson's Point and Dawes Point abutment towers has been continued steadily. The masonry at the Dawes Point tower is nearing completion until concrete walls can be raised above the present level of R.L. 155.50.
At Milson's Point the concrete lining of the anchorage tunnels was poured and the two heavy concrete saddles to change the direction of the cables at the top of the cable tunnel were completed. At Dawes Point the concrete cable saddles had been completed, and the steel saddles were placed and grouted in position, and the cables were drawn through the saddles and socketed.
Commencing in August the anchorage cables were drawn through the tunnel at Dawes Point, and at the end of .June 102 cables had been so drawn and the majority socketed, leaving a further 26 to be drawn to complete the quota of 128 in the complete anchorage system.
The quarry at Moruya is turning out stone faster than it can be placed in position and the site previously occupied by Langdon's timber yard is being prepared as a storage yard.
The following are the quantities for the masonry and concrete work during the year: —
No. 1 concrete ... ... ... ... ... ... ... ... ... ... ... ... ...12,678 cubic yards.
Granite masonry ... ... ... ... ... ... ... ... ... ... ... ....3,672 ,,
Four cut work on granite masonry ... ... ... ..17,589 square feet.
(b) Fabrication of Steelwork.
During the year 1,928 tons of carbon steel were delivered at Milson's Point of which 1,101 tons were rolled in England and the balance of 827 tons rolled at Newcastle by the Broken Hill Pty. Co. Ltd. The total silicon steel delivery during the year amounted to 11,169 tons all rolled in England.
The total steel delivered to date is 31,063 tons, of which 14,853 tons is silicon steel, the above figures being exclusive of main and approach span bearings.
During the year 2,245 gallons of paint and 68 gallons of dryers were delivered, making a total of 7,735 gallons of paint and 273 gallons of dryers delivered to the end of June.
The total deliveries of rivets amount to 1,792 tons, of which 616 tons were delivered during the year.
The total tonnage which had to be fabricated in the shops at Milson's Point is 49,014 tons, of this 20,340 tons have been fabricated, leaving 28,674 tons to be fabricated.
The first complete member for the main arch was weighed during July, 1928. The average output per month since the commencement of the arch fabrication is 608 tons per month over a period of twelve months. This figure should show a considerable improvement from now on as during the period under review the Shops have had to turn out special lifting gear, stagings, anchorage links, & c , the bulk of which is now completed.
There has been a gradual decrease in the number of gallons of paint per ton due to the fact that the heavier material is gradually superseding the lighter material, consequently there is less surface to cover per ton.
To expedite the fabrication of steelwork of the main span a third shift was commenced in the workshops in September, 1928. The average number of men employed oh the third .shift is about 40, while there are about 150 on the second shift, and an average of about 420 on the day shift.
The graph herewith shows the quantities of material delivered, fabricated, erected in place and completely riveted since the first steel delivery.
(c) Erection of Steelwork.
At the commencement of the year under review the travelling gantry of the creeper crane had been erected on the ramp on the south side and preparations were being made for the erection of the creeper crane jib. The erection of the jib, and the main and auxiliary hoists of the creeper crane were completed during September.
Approach Span No. 10 was completed during August, the false-work being completely removed during November.
On 14th August a start was made with threading the anchorage cables through the tunnel and pylon saddles, the terminals of the cables hanging over the front wall of the pylon.
The cables were unwound from a wooden drum fitted with a brake band and mounted on the back stays of the Eastern Pylon saddle, the cables being drawn through the paddles and tunnel anchorages by means of winches mounted on the pylon.
On the 15th October the top saddles of the southern main bearing which had been in the workshops for the purpose of fitting to the bottom chord sections, were placed in position on the pins of the main bearings. The pins and saddles were thoroughly cleaned and lubricated with flaked graphite and cylinder oil before the saddles were placed in position.
The 160-ton floating crane " Titan " was hired by the Contractors from Cockatoo Island Dockyard for the purpose of lifting the main arch members from the pontoon to within reach of the creeper crane jib.
On the 25th October the creeper crane was brought forward up the ramp and before the end of October the first section of the bottom chord was lifted into position, on the bearing.
During November and December the end frame and portal bracing were erected and the temporary
struts which, will ultimately be the posts, 8-9, placed in position.
During the riveting of the end frame connections, the cutting to length and socketting of the cables were proceeding and on 19th December the eight cables forming the temporary anchorage were attached at the top of the end post.
By the end of January seventy-four cables had been threaded through the cable tunnel and fifty-five cables socketted at each end.
Early in March the first panel of the main arch was completed and the creeper crane moved forward and was completely on the main arch steelwork. The creeper crane ramp was then dismantled from the south pylon and re-erection commenced on the north pylon.
By the end of June, 1929, the first three panels of the arch had been completely erected on the Dawes Point side, and on 23rd June the northern creeper ermine was erected on the steel ramp ready to commence the erection of the main arch from the northern side.
At the end of June forty-four cables of the Dawes Point anchorage had been tensioned
3. CONSTRUCTION OF THE SOUTHERN APPROACH BY THE SYDNEY HARBOUR BRIDGE BRANCH.
During the year work has proceeded steadily over the whole of the Southern Approach.
(a) Excavation in Tunnels.
The excavations for the double track tunnel for the Shore tracks and the signal cabin under Lang Park were completed, the total quantity of excavation being 4,437 cubic yards.
The excavation of the signal cabin called for special care as it is located directly under the City Railway compressors which, together with the soil of the park contributed their full weight to the timbering.
(b) Excavation in Open Cut.
The cutting for the four tracks from Grosvenor-street to Little Essex-street was practically completed, the quantity of excavation being 36,710 cubic yards. The two double track cuttings between Argyle Cut and Little Essex-streets were completed as far a could be done without cutting off the roadway access.
The total quantity of excavation, including footings for walls, abutments, cable tunnel, and various regradings was 76,328 cubic yards.
(c) Concrete Work.
Concrete was placed during the year in walls and flat top construction of the cut and cover work from Jamieson-street to Argyle Cut, in lining the tunnels under York-street, in the arch roof of cut and cover construction, and in the piers and abutments of the three reinforced concrete arches at the southern end of Contract.
A total of 41,590 cubic yards of concrete were placed.
(d) Deviation of Services.
The excavation and construction in the vicinity of Essex-street called for the removal and deviation of several underground and overhead services. The chief alterations were as given below. A water main was removed from Princes-street, necessitating the laying of a temporary 4-inch main in Essex-street to supply Fort-street Girls' High School, the Observatory and the Weather Bureau. Aerial cable and telephone poles were removed.
The City Council low tension feeders to Miller's Point were deviated to clear the excavation. The stormwater, sewer and gas mains were moved from the junction of York-street North and Grosvenor-street.
(e) General.
A considerable amount of fencing, practically all of a temporary nature to enclose the working areas, was carried out, the total quantity being 3,517 lineal feet.
The flat top construction south of Grosvenor-street was waterproofed with bituminous sheeting. This was carried out, by contract, by the Ormonoid Roofing Company, the total quantity being 996 square yards.
The Grosvenor Hotel, the Grand Hotel and about half-a-dozen other properties constituted the tally of buildings demolished during the year.
From 282 minimum, the number of men reached a maximum of 362, the average number for the twelve months being 316.
4. FINANCIAL REVIEW.
(a) Land Tax.
To defray one-third of the capital cost of the construction and laud resumptions and the maintenance and lighting of the roadways and footways of the Sydney Harbour Bridge and approaches from Bay Road Station on the Northern side of the harbour to Wynyard Station on the South side, a land tax of one half-penny in the pound was imposed upon the unimproved capital value of all rateable land with the City of Sydney, the Municipalities of North Sydney, Mosman, Manly, Lane Cove, Ku-ring-gai and Willoughby, the Shire of Warringah and portion of the Shire of Hornsby.
The tax was first imposed in 1923; the rates for the years 1923-29 are as shown on table appended. Of the amount of £1,094,754 12s. 6d. due to 30th June, 1929, £909,171 3s. 5d. was paid to the Special Deposit Fund, leaving a balance of £185,583 9s. 1d. to be paid before 31st December, 1929.
Interest received upon the amounts received from the rate levy is calculated on the daily balance and to 30th Juno, 1929; a total of £101,021 6s. 11d. has been credited to the rates account as interest.
The table shows the details of rates due since the tax was first imposed, the payments to 30th June, 1929, and the balance outstanding at that date.
Rate Levy—Payments and Outstanding Amounts at 30th June, 1929.
(b) Expenditure.
The total expenditure to 30th June, 1929, is shown on the following table. The cost to date of the Bridge and Approaches, including land resumptions, interest on construction, and all expenditure prior to 1st July, 1923, is £4,815,131 153. 11d., of which amount the resumptions have cost £l,200204 5s. 11d, but a large proportion of this, if not the full amount, will be recouped at the completion of the Bridge by the disposal of the residues.
It will be seen that the wages variation to date on the contract of Dorman, Long & Co. is a little more than 10 per cent, of the amount paid to date for construction. This figure has risen slightly during the past year on account of the greater margin above ordinary award wages due to the men now being engaged upon the main span.
Expenditure to 30th June, 1929.
5. IMPROVEMENTS TO ROADWAYS IN APPROACH TO BRIDGE.
During the year the Drawing Office staff have made investigations, including carrying out the necessary field work, of a scheme of roadways to improve and supplement the existing roadways, on both sides of the Harbour, in approach to the Bridge.
The outstanding section of the work was the location of a new highway from near Alfred-street, North Sydney, to Military-road.
6. STAFF.
The number of men employed on the Sydney Harbour Bridge and Approaches as at 30th June, 1929, was approximately 1,650. Dorman, Long & Co. employ 200at Moruya Quarry, and in the transport of material from Moruya to Sydney; about 920 are employed in placing concrete and granite masonry, fabricating steelwork in the workshops and in erecting the steelwork, whilst 530 men were employed on the construction of the approaches under the Public Works Department.
As in previous years several draftsmen have resigned, leaving to obtain higher salaries elsewhere. On account of the difficulty in obtaining suitable men in New South Wales a number of draftsmen have been brought from Victoria and South Australia.
I again wish to express my appreciation of the manner in which the staff of the Sydney Harbour Bridge Branch have carried out their duties during the past year.
J. J. C. BRADFIELD,
Chief Engineer, Sydney Harbour Bridge.
26th September, 1929.
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