1926 Public Works Department Annual Report.
Sydney Harbour Bridge Branch.
Report for the year ended 30th June, 1926.
I have the honor to submit the following report on the work of this Branch for the year ending 30th June, l926: -
1. CONSTRUCTION OF NORTHERN APPROACH.
Ferry Docks.
The new ferry docks in duplicate which were constructed at Jeffrey-street were put into commission on 20th July, 1925, and the traffic routed along the new road from Jeffrey-street to Burton-street, and thence to Alfred-street. This diversion of the vehicular ferry traffic gave the contractors vacant possession of a large area of land at Milson's Point and enabled them to commence the construction of the Northern Abutment Tower and the Approach Piers.
Tunnels.
On 1st July, 1925, No. 1 tunnel, the Up Shore local, had been completed and the goods service to North Sydney Station Yard was in operation as from 26th March, 1925, whilst the excavation for No. 2, the Down Shore local tunnel, was nearing completion and had been carried to a point 162 feet from the Miller-street entrance; No. 4 tunnel, the Down Shore, had been driven 99 feet.
The double tunnel for the Up and Down Shore tracks was commenced at Bank-street on 24th July, 1925, and No. 3 tunnel, the Up Shore, at Miller-street on 5th January, 1926. During the year ending 30th June, 1926, good progress was made; some 31,336 cubic yards of rock were excavated and 2,634 cubic yards of concrete lining placed in the tunnels.
Open Cut Excavation.
The open cut excavation from Bay Road to the tunnel entrances at Bank-street was completed, also the excavation for the forming of Clifton-street. The excavation for the site of North Sydney Station between Miller-street and Walker-street was completed except for the area required for the road to the Goods Shed, the total quantity excavated for the twelve months being 10,238 cubic yards.
Roadmaking.
The approach to the vehicular ferry necessitated a new road between Pitt-street and Fitzroy-street; Broughton-street and Burton-street were resurfaced; Carr-street, Clifton-street, Euroka-street and Woolcott-street were graded, ballasted, kerbed and guttered with concrete kerbing and guttering.
Drainage.
A system of drainage has been completed to provide for the stormwater from the west nide of Alfred -street and from Paul-street. Western Wharf-road and Northcliffe-street to the harbour, the channels for which had been destroyed by the excavation for the workshops.
Installation of Plant—Field Office.
To enable excavation to be completed at the site of North Sydney Station, the Field Office was transferred from Bolwarra Flats to Alfred-street; Bolwarra Flats were then sold and demolished. The store, timber racks, compressor sheds, cooling towers, &c., erected between Bay Road and Walker-street, not required to complete the work in that section, were transferred to Alfred-street; the garage in Alfred-street is now used as the compressor shed. The stone crusher and bins were transferred from Euroka-street to Brisbane-street, and all the plant required has now been installed to enable the Northern Approach to be completed; the area bounded by Brisbane, McDougall, Alfred, and Willoughby-streets has been fenced in as a working area; other fencing was also done, the total length being 50 chains.
Disposal of Spoil.
The material excavated has been deposited where possible in its permanent position in the Roadway Approach to the Bridge between Junction-street and Willoughby-street; the balance has been stored for future use in the Brisbane-street dump or has been used as concrete metal and for roadmaking.
Land Resumption.
There has been a difficulty in obtaining vacant possession of all the property necessary to enable work to proceed according to schedule.
Houses, including the separate sales of Messrs. Langdon and Langdon's workshops, timber sheds and gantry, and the Milson's Point Arcade in one lot, numbered 88; these were auctioned for demolition, the gross receipts being £5,378 10s. in addition, the property, Lorna Doone, was demolished by the owner with the concurrence of the Department.
Up to 30th June, 1926, Messrs. Dorman, Long & Company had not been given possession of the whole of the land required at Milson's Point, as certain portions of the Sydney Ferries' property at that date were not available for contract purposes.
The total amount paid for land resumptions is as under: —
Up to 30th June, 1925..............................£119,948--8-7
1st July, 1925, to 30th June, 1926........£245,382--3-5
Total...................................£365,330-12-0
2. MAIN BRIDGE — DORMAN, LONG & COMPANY'S CONTRACT.
Fabricating Shops.
To enable the fabricating shops at Milson's Point to be constructed, the Contractors had to excavate 50,307 cubic yards of rock along the cliff face. With the approval of the Harbour Trust, the major portion of the material excavated was tipped along the foreshores, realigning and straightening them. On the area acquired from the Railway Department and areas made available by resumption and the excavation and reclamation above-mentioned, two large steel frame fabricating shops have been erected, also the crane runways used for unloading the steel transported by water and for storing it in the stock yard adjacent to the shops.
The erection of the fabricating shops was commenced on 28th May, 1925; they were completed at the end of June, 1926. The light shop in which the approach spans, cross girders and wind-bracing will be fabricated, and portions of the heaviest members in the main span, is 589 feet long x 130 feet wide in two bays. A template floor, 200 feet long and 130 feet wide, has been provided in an upper storey where all members will be drawn out full size before fabrication begins.
The heavy fabricating shop in which the portions of the heaviest members will be completed is 500 feet long and 147 feet wide in one bay. To handle the steelwork in this shop, two 120-ton overhead travelling cranes of 137 feet clear span, electrically operated, have been installed, and at the extreme end of the shop a dock 120 feet long and 25 ft. 6 in. wide has been constructed, where the steel members as fabricated will be loaded on a barge and towed to where they are required.
These shops are the most modern bridge fabricating shops yet erected. Both are equipped with the best modern machinery, all specially designed for the construction of the Sydney Harbour Bridge, which will necessitate the fabrication of the heaviest .steel members yet undertaken anywhere in the world.
The erection of the shops was delayed for a period of approximately five months by the shipping strike in Great Britain, as the material and machinery from overseas could not be transported to Sydney.
Under normal working conditions the shops have a fabricating capacity of 1,200 tons of steel per month or 14,000 tons per annum.
The plant enumerated below has been installed: —
Beam Bending and Straightening Machine: —Single-ended machine for straightening and bending joists up to 24 in. x 7½ in.
Horizontal Plate Straightening Machine: —To flatten plates from ⅜ in. to 2¼ in. in thickness x 12 ft. in width.
Pneumatic Power Hammer — 5 cwt.
Portable Hydraulic Riveters (2). — To exert a pressure of 80 tons. Approximate weight, 11 tons. Stroke 5½; gap, 9 ft. 6 in. wide x 3 ft. deep.
Portable Hydraulic Riveters (2). — Similar to above, but with gap 4 ft. 6 in. deep x 3 ft. wide. Approximate weight, 4½ tons.
Portable Hydraulic Riveters (2). — Similar to above, but with gap 7 ft. 6 in. deep x 1 ft. 10 in. wide. To exert a pressure of 45 tons. Approximate weight, 4 tons.
Portable Hydraulic Riveters (2). — Similar to above, but with gap 6 ft. deep x 1 ft. 10 in. wide. Approximate weight, 3½ tons.
Hydraulic Pressure Pumps (2). — Three-row vertical.
Hydraulic Horizontal Bending Press.—Complete with bending pin and abutment block; 100 tons.
Plate Edge Planing Machine. — Capable of planing plates 66 ft. long x 2¼ in. thick.
Twist Drill Grinding Machine.
Vertical Drilling Machine. — Fitted with auxiliary high speed spindle.
38 in. High Speed Cold Sawing Machine. — To cut up to 24 in. x 7½ in. joists and 12 in. x 12 in. angles.
Rotary Planer or End Milling Machine. — For machining the ends of structural members up to 12 f t .x 4 ft.
Double-ended Punching Machine. — To punch 1¼in. diameter holes through 1¼ in. thick steel.
Rivet Furnaces. — Ten.
Double Angle Shearing Machine. — To crop angles up to 8 in. x 8 in. x 1¼ in., either at right angles to their length or at any bevel up to 45°.
Horizontal and Vertical Side Planing Machine. — To plane 12 ft. horizontally and 10 ft. vertically on either side of the upright.
Plate Shearing Machine. — To shear plates 6 ft. wide up to 1¼ in. thick.
28-in . Shaping Machine.
Plate Shearing Machine. — To shear plates 6 ft. wide up to 1¾ in. thick.
Radial Drilling Machines (18). — High speed; central thrust; for plate and girder work.
Bogie Type Radial Drilling Machines (9). — Improved Duplex; four speed gear-box.
Bogie Type Radial Drilling Machines (3). — Similar to above, with one speed only to spindle.
Bogie Type Radial Drilling Machines (3). — Similar to above, but arranged for inverted drilling.
Suspended Type Drilling Machines (6).— These are a special type of drilling machine, with a vertical and horizontal traverse.
Planing Machine. — To plane 6 ft. wide x 6 ft. high x 18 ft. long.
10-ft Radial Drilling and Boring Machine. — This machine is provided with angle plate for fixing cast steel saddles in position
whilst being bored.
Double-ended Grinding Machine. — Fitted with wheels 20 in. diameter x 2½ in. wide.
Shear Blade Grinding Machine. — To grind plates up to 10 ft. long x 9 in. wide.
Grind-stone. — 72 in. diameter x 9 in. face.
Bolt Screwing Machine. — To screw up to 1½ in. diameter.
Automatic Bolt Screwing Machine. — " Heaps."
Weighbridge. — 16 ft, 80-ton capacity.
Weighbridge. — 16 ft., 60 ton capacity.
Girder Ending Machine.
Plate Edge Planing Machine. — 22 ft stroke.
Acme Single Sawing Machine. — 5in.
Lathe.
Vertical Wood Boring Machine. — Robinson " type, P.K. No. 1.
Turret Lathe. — 10in.
Double Floor Grinder.
Automatic Saw Sharpening Machine. — To 42 in. diameter.
Shaping Machine.— 18 in. stroke.
Hand Winches (2). — 30-35 cwt. direct lift from barrel.
Portable Pneumatic Riveting Machine. — For 1 in. diameter rivets.
Pneumatic Riveting Guns (2). — For rivets 10½ in. x 5/32 in.
Horizontal Water-jacketed Air Compressors (2) — Two stage belt driven; 10 in. stroke.
Cranes.
Travelling Wharf Cranes (2). — 10-ton; overhead.
Electric Travelling Cranes (2). — 120ton; 137 ft. span; overhead.
Electric Travelling Cranes (4). — 25-ton; overhead.
Electric Travelling Cranes (2). — 5-ton; Semi-Goliath; overhead.
Electric Travelling Crane (1). — Double 5 ton; overhead.
Fabrication.
The fabrication of the steelwork for Span No. 1 was commenced on 7th April, 1926.
The tonnage of steel unloaded at the fabricating shops up to 30th June, is as under:—
tons cwt. qr. lb.
From Broken Hill Proprietary Company, Newcastle...........1,050 12 0 0
From Dorman, Long & Company’s Works, England..............673 10 3 0
Total.....................................1,724 2 3 0
Prior to the coal strike in England all the steel plates required for Span No. 1 had not been manufactured at Redcar, near Middlesbrough, and on this account fabrication at Milson's Point has been delayed awaiting the balance of the plates required, some 200 tons. The coal strike in England has delayed the manufacture of the steelwork by approximately five months.
The total hold-up due to the shipping and coal strikes in England is about ten months; this, however, does not necessarily mean that the Contract is ten months behind time.
The intermediate cross frames, cross girders, roadway joists, and portions of the top and bottom chord members of Span No. 1 were under construction on 30th June; the number of men employed in the shops was 130.
3.CONSTRUCTION AT DAWES' POINT — DORMAN, LONG AND CO’S CONTRACT.
Excavation.
The excavation for the abutments for Piers 1 to 8 of the Approach Spars and for the abutment towers and skewbacks at Dawes’ Point was continued throughout the year and good progress was made. Owing to faulty rock and a layer of shale being disclosed by the diamond drill cores taken over the area of the foundations, the excavation for the skewbacks had to be taken deeper than designed. Earth excavations, 3,420 cubic yards, and rock excavation, 18,241 cubic yards, were removed, the major portion was dumped from hopper barges outside the Heads; the remainder was used cs filling in Dawes' Point Park.
The excavation for the shafts and anchorage tunnel required fer the erection of the main arch was completed during the year. The shafts are 25 ft. x 0 ft. in section on a slope of 45 degrees, some 128 feet deep, connected together at the bottom by a semi-circular tunnel of the same dimensions.
Concrete.
The concrete in the foundations of the approach piers and abutments has all been placed. In the skewbacks, to minimise shrinkage due to the setting of the concrete, the concrete is being poured in hexagonal slabs of the full width of the skewbacks (40 feet) in one operation; the upper surface of each slab is allowed to set seven days and the sides three days before any contiguous concrete is placed.
The concrete consists of granite aggregate, the run of the crusher, Nepean sand and cement in the proportions 4 : 1¾ : 1. Sample blocks tested at twenty-eight days gave an average crushing strength of 218 tons per square foot. Concrete 3,354 cubic yards in Approach Piers 1 to 8 and abutments, and 4,748 cubic yards in skewbacks of south pylon, a total of 8,102 cubic yards was placed.
Masonry.
The masonry facing for the piers of the approach spans is proceeding satisfactorily. The stone being obtained from the quarry at Moruya is excellent; 822 cubic yards of masonry have been placed in the approach piers during the past twelve months.
Falsework.
The falsework for the erection of Spans 1 and 2 has been completed for some time, but owing to the delay in fabrication of Span No. 1, caused by the coal strike, no steel was erected during the year.
Four well-braced timber towers, 110 feet high, have been erected at the site of the main pier at Dawes' Point and two 7-ton steam derrick cranes have been placed thereon. These cranes will build the abutment towers and pylons to deck level, approximately 170 feet above water level.
A heavy timber tower haw been erected near George-street North and a 25-ton electric crane seated thereon. This crane will travel towards Dawes' Point to erect he steelwork of the approach spans as it is received from the Milson's Point fabricating shops.
4. CONSTRUCTION AT MILSON'S POINT — DORMAN LONG AND COMPANY'S CONTRACT.
Excavation.
The excavation for the abutments and piers of the approach spans, and for the abutment tower and skewbacks, was undertaken as soon as the necessary laud became available. The rock on the northern side of the harbour generally is better and more evenly bedded than on the southern side. Diamond drill bores disclosed sound rock 50 feet below the finished excavation for the skewbacks. These were excavated as designed, 90 feet long. 40 feet wide, 30 feet deep at harbour face, and stepped towards the back, the steps corresponding with the bedding planes of the sandstone. Earth excavation 2,161 cubic yards, and rock excavation, 14,604 cubic yards, were removed and spread in the vicinity of the abutment tower.
The excavation for the shafts and anchorage tunnel was commenced in May last, being delayed for some months owing to the time taken in obtaining a transfer of the license of the Milson's Point Hotel to an hotel to be erected at a new site in Alfred-street. The dimensions of the shafts and tunnel are similar to those of the anchorage tunnel at Daws' Point.
Concrete.
Owing to a shortage of granite aggregate, no concrete has been placed in the skewbacks, although the excavation therefor was completed in April last. In the abutments and in the foundations and bearings or the approach piers, 1,857 cubic yards of concrete were placed in position.
Masonry.
The masonry facing for the approach piers did not proceed as rapidly as was anticipated, owing to the difficulty in obtaining sufficient masons and quarrymen skilled in granite working at Moruya.
On 30th June, some 194 cubic yards of masonry had been placed in position.
Falsework.
The erection of the falsework and of the substructure generally is not in such a forward state as on the southern side.
The falsework for the erection of spans 6 and 7 was commenced as was also the timber work for the four heavy towers for the erection of the northern abutment tower and pylon.
The erection of the tower at Fitzroy-street to support the 25-tun crane to be used to erect Spans 6, 7, 8. 9 and 10 has not yet been commenced. The delay caused by the shipping and coal strike is having its reflex on the construction of the northern approach. It will not be possible to commence the construction of the arch across Fitzroy-street for at least twelve months from 30th June, or a delay of six months in the programme I had outlined.
The Moruya Quarry.
The equipment and plant at the quarry are quite modern, but owing to a .shortage of masons and quarrymen, and disputes as to a living allowance at Moruya, the supply of facing stone and aggregate has not been equal to the demand.
With the consent of the unions concerned, men skilled in granite working have been brought to New South Wales. A larger crusher is also being installed.
During the coming year the output of facing stone and aggregate should be facilitated. Two of the three freighters built at Walsh Island are in service conveying material from Moruya to Sydney, and with an increased output at the quarry it is anticipated the third will be in commission during the ensuing year.
5.CONSTRUCTION OF SOUTHERN APPROACHES.
Survey.
The centre lines of the tracks providing for a ruling grade of 1 in 30 (compensated) for curvature were calculated and located on the ground.
On 1st July, 1925, the retaining wall along Hickson-road was in course of construction between Piers 2 and 4. It is now completed, except for portion of the parapet wall, which cannot be undertaken until the falsework for the erection of Spans 1, 2, and 3 has been removed. This wall was constructed by Messrs. Dorman, Long and Company at schedule rates as an addition to their contract. Some of the material excavated for the approach piers and the abutment towers was placed behind the retaining wall along Hickson-road, and the area thus formed, together with the area of portions of the streets which will be included in Dawes" Point Park when the bridge is complete, will add about 1 acre of land to the park. From the park adjacent to the wall a view of the harbour looking east, probably unsurpassed from any other vantage point along the harbour foreshores, is obtained.
Earth (1,255 cubic yards) and rock (4,424 cubic yards) were excavated during the year, and 7,025 cubic yards of concrete were placed in the retaining wall.
6. LAND TAX.
To defray one third of the capital cost of the construction of the bridge and land resumptions, a land tax of one halfpenny in the pound has been imposed on the unimproved capital value of 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 1923-26 are shown below. Of this amount up to 30 June, £399,631 3s. was paid to the special fund, leaving a balance of £135,842 4s. 10d. to be paid before 31st December, 1926.
Financial.
The total expenditure up to 30th June, 1926, is shown by the table.
It will be seen that on Dorman, Long & Company's contract for the main bridge the wages variation to date is approximately 9 per cent, of the amount paid for construction. The total cost of the bridge to date, including all expenditure prior to 1st July, 1923, is £942,164 2s. ld.
Concrete Tests.
Tests on granite concrete have been made under the Specification to determine the required proportions of the constituents of —
(a) No. 2 concrete for approach piers,
(b) No. 1 concrete for abutments towers,
(c) Special granite concrete for use under bearings of approach spans.
The aggregate from which test cubes were made consisted of run of crusher from 2½ in. downwards passed over ¼in. screen at the quarry, thereby eliminating some of the dust. All tests were made with the aggregate graded the same as an average sample taken from supply. The grading in all cases is: —
(a) No. 2 Concrete.
Two series of mixes were tested, one the run of crusher as above, the other using the aggregate of the same grading but without the material passing the 0.25-in. sieve. Results: —
The results indicate that the addition of granite, ¼ in. to dust, is roughly equivalent to 1 part of sand, and that, using a mixture 1 cement : 2 Nepean sand : 5 parts granite aggregate 2½ iu. to dust, the crushing strength at 28 days may be taken at 3000lb. per square inch, a good working mix being obtained. Subsequent tests on field mixed concrete have substantiated the results.
(b) No. 1 Concrete.
For No. 1 concrete two similar series of tests were performed, using 4 parts of aggregate, of the same grading as before. Results: —
The mixture, 1 : 1¾ : 4, aggregate 2½ in. to dust, gave a good working mix, with high strength at 28 days, the crushing strength being taken at 3,200 lb. per square inch.
(c) Special Granite Concrete.
A series of long-date tests are being performed at the University on cubes mixed by the Department for the special concrete under bearings. The aggregate used was 2½ in. to dust, of the standard grading. Results: —
Further tests of this series have yet to be completed, but the superiority of the mix 1 : 1¼ : 3 is apparent at once.
Staff.
All officers, except myself, employed in connection with the design and erection of the main bridge and the design and construction of the bridge approaches, have, at the request of the Public Works Department, either been set aside from the then existing Railway staff or have been appointed by the Railway Department as bridge officers. Their salaries are paid by the Railway Department and recouped from the Bridge vote.
As Chief Engineer, I deal directly with the Under Secretary for Public Works in all matters appertaining to the bridge, receiving an allowance from the department for my work.
In conclusion, I wish to express my appreciation of the work of the staff during the past year.
J. J. C. BRADFIELD,
Chief Engineer, Sydney Harbour Bridge,
11th October, 1926.
