The Designers

The ideas that formed the timber truss bridges of New South Wales (NSW) came from many sources, mostly taking shape in the drawing offices of the Department of Public Works in Sydney. In the Australian colonies where the designers were public servants an administrative head signed plans, so a designer’s identity is not always obvious to today’s researchers. The search is not helped by an inadequate legal definition of design as ‘a scheme or plan conceived in the mind’.

As a former NSW chief bridge engineer explains, this

singles out the one who proposed the form of the bridge and doesn’t equate with any engineering definition. While the designer proposed the outline of a bridge, it was ‘the stress man’ who did all the calculations to make it work and sculpt it so it would work.1

Among the many engineers employed on bridge design during NSW’ timber truss bridge era — from the design of the first in 1854 to completion of the last in 1936 — five men stand out for the distinctive timber truss types they created for Australian conditions.

The five types were retrospectively classified for the practical purpose of bridge maintenance, with the fifth type not identified until 1987, in the DMR Timber Truss Bridge Manual. Since then a growing appreciation of these historic bridges has drawn the theory behind their typology out of the engineering classroom to become the basis of assessment of the heritage values of the timber truss bridges of NSW.

In focussing on the designers, this chapter advances that typology, firstly by naming all five truss types for their creators, William Bennett, John McDonald, Percy Allan, Ernest de Burgh, and Harvey Dare. Also, through the haze surrounding Australia’s very first timber truss bridges, William Weaver emerges as the engineer who introduced the timber truss bridge to NSW though both the bridges and their designer were unrecognised.

The biographical approach in this chapter fills in some fascinating facets of the lives of the designers to complement the intriguing details of their designs given in Chapter 2 ‘The development of the truss’.

In finding the designers – those who ‘conceived the plan’ and those who computed the figures that gave the bridge its working form — it helps to have a commencement date. For this purpose the date of a plan, or of the call for tenders from builders, is better evidence than the date of completion, which might refer to various events weeks, months and even years apart – the date work is finished, the date the bridge is in operation, or the date of its official opening. Wherever possible, the commencement dates are provided here and any ‘completion’ dates specified.

The story of timber truss bridges in Australia begins with engineer William Weaver, engaged for his bridge expertise by the NSW Colonial Architect’s Office in 1851. Then aged 23, Weaver had worked in the firm of Isambard Kingdom Brunel whose multiple British railways contracts made him an iron bridge engineering legend. Brunel was in business, and as his customers included the under- capitalised railway companies needing low-cost materials, his engineers also gained experience in designing timber bridges and viaducts. One of several Brunel engineers whose expertise was sought in the Australian colonies, Weaver arrived in 1850, the same year as BH Babbage, bound for South Australia where he built the Colony’s first railway. In NSW Weaver was in charge of bridge design for five years, including his term as Colonial Architect from 1854 to 1856.

Weaver’s first colonial work was the laminated arch Victoria Bridge, built over Wallis Creek at East Maitland in 1851-52 (see Figure 3.1). Colonial Architect Edmund Blacket was enmeshed in the problem of assessing the vigorously competitive local proposals for this bridge when he appointed Weaver. Weaver next designed its ‘sister’, the Hume Bridge built over the Yass River at Yass from November 1853-September 1854, then the Fitzroy Bridge over South Creek at Windsor and the Denison Bridge over the Macquarie River at Bathurst in 1855.2

Reportedly ‘built from his own designs’, these followed British railway timber bridge design, including Brunel’s only laminated arch bridge, built in 1840 to carry the Great Western Railway line over the Avon River at Bath, where Weaver had been assistant engineer in 1846. In applying this design in NSW Weaver sidestepped the ‘formidable undertaking’ of building stone bridges at sites like these, as well as avoiding labour- intensive construction.

Weaver’s plans, or at least his innovation, produced two more laminated arch bridges, over the Peel River at Tamworth and over the Murrumbidgee River at Wagga Wagga. Building of both began under Ben Hay Martindale and his assistant engineer William Bennett, and continued after the resignation of both men at the end of 1860. By the time these bridges were finished in 1862, Bennett had returned as the Colony’s new Roads Engineer.3

It was the unsung Weaver who brought the timber truss bridge to NSW with his Carcoar Bridge, built over the Belubula River from July 1855 – January 1856. Though new to the Australian colonies, as Chapter 2 ‘The development of the truss’ explains the truss form was old, a revival of Palladian bridge trusses that Weaver knew from Brunel, whose four classes of timber viaduct were based on these trusses. In 1855 the Sydney Morning Herald explained this innovation, where instead of laminated arches, trusses ‘framed on the principle of the ordinary ‘queen’s-post roof’’ provided a bridge 173 feet (52.7 m) in length with three 52 feet (15.9 m) spans and a deck 18 feet (5.5 m) wide.5

Weaver designed at least one other bridge with a timber truss, across Paddy’s River on the Great Southern Road, though no evidence is yet available that the bridge completed in 1855 followed the plan. Showing a timber trestle bridge with one queen post and one king bolt truss, this was dated 30 August 1854, when Weaver was still Clerk of Works, soon after he completed the Carcoar plan.6 It was an eventful year for Weaver. It included his visits to the Hume Bridge site at Yass and his marriage to Frances Broughton, daughter of a prominent local family there and as well, his appointment that October as Colonial Architect, succeeding Blacket.

Troubles in his office resulted in orders ‘for the cessation of all public works after the completion of the Bathurst and Carcoar bridges’ and Weaver resigned in March 1856.7 Then in his 30s, he had considerable success in private architectural and engineering practices in Sydney but in 1864, the year his fifth child was born, he left, alone, for an engineering post in New Zealand. An Associate Member of the Institution of Civil Engineers (ICE) from 1851, Weaver was elected a Member in 1868, just months before his early death ended a troubled personal and professional life.8

Even before the 29-year-old Irish surveyor and engineer arrived in NSW, William Christopher Bennett’s career made for an epic tale including an eccentric uncle keen to make him heir to a Tudor castle and a mother who preferred her son surveying in the wilds of British Colombia rather than being shackled to a crumbling legacy. The young surveyor was part of the British attempt to find a route for a shipping canal across the Isthmus of Panama to link the Atlantic and Pacific oceans; his heroic initiative in the rescue of a US Navy crew there had Bennett featured in US Harper’s Magazine. NSW read about the young Irishman before he set foot on shore, with coverage of his heroism in The Times in London relayed in the Sydney Morning Herald in January 1855. Bennett was then in New Zealand seeking work, but witnessed instead the devastating earthquake that destroyed the 50-year-old town of Wellington.9

Leaving New Zealand for NSW, he found employment in Surveyor- General Sir Thomas Mitchell’s army of temporary staff. The following year Bennett assisted Edward Bell in planning Sydney’s sewerage system, and in 1857 surveyed the extension of the Colony’s first railway south to Campbelltown for Chief Engineer John Whitton.10

In June that year the Colony’s first Commissioner for Internal Communications, including railways, roads and bridges, and the electric telegraph, arrived. A British Army engineer, Ben Hay Martindale’s first report in 1857 made little of Mitchell’s extraordinary contribution, noting some 340 miles of existing roads with ‘scarcely a creek or river bridged’. He soon recruited Bennett, despatching him on an expedition to inspect the Great Southern Road that winter. Bennett’s thorough report included a warning on the new bridge at Marsden’s Crossing place over the Wollondilly River. His advice for folding rather than fixed railings as the plans had the deck of the bridge below flood level was unheeded and he ‘requested that I might not be held responsible for its success’. His asperity was justified when the bridge was swept away in floods in 1870.

By early 1858 Martindale had appointed Bennett assistant engineer in the roads and bridges section of Internal Communications, with his first task that summer to examine the Parramatta-Bathurst route of the main western road. Bennett recommended bridges for Junction Creek and Cox’s River, with his report on the condition of the road justifying the Bathurst Times’ description:

The road from Lapstone Hill to Victoria River was never in a worse condition than it is at present, and, unless substantial and costly repairs are at once commenced, there will be greater difficulty in crossing the mountains next winter than there was last year. It is absurd to suppose that any permanent good can be accomplished with the small amount of funds annually appropriated for the repair of the Western Roads… All that we can say is, something must be done, and that quickly.

That winter Bennett was in Bathurst again, superintending major repairs after severe flood- damage to Weaver’s Denison Bridge. In spring Martindale joined him in an inspection of the road over the Blue Mountains, when at least the approach road through Penrith gratified locals:

It cannot but be apparent to travellers that a vast improvement is being made on the Western Road by the filling up of holes, which process, together with the aid of the sun, has indeed had a wonderful effect in making our main thoroughfare at least passable again.11

When he set out on the western road with Martindale, Bennett had just returned from examining the whole of the main northern road, riding along the route from Morpeth to Black Creek, from there up to the Murrurundi Gap, and on to Armidale. Despite a serious accident when horse and rider fell on a steep decline, Martindale noted the intrepid Bennett was back at work the next day. Among deviations Bennett sought was one to the Armidale route through Salisbury Plain, recommending the more westerly route through Uralla ‘on account of the rising township and gold field there’.

Everywhere his party lodged, locals provided Bennett with ample evidence of the need for bridges. Reporting that the mail contractor was regularly unable to cross Sandy Creek north of Muswellbrook, he noted the site was perfect for a simple timber beam bridge as ‘there is not much driftwood, the bottom of creek is sandy, and ironbark is abundant’. More challenging was the ‘immediate need’ for a large bridge over the Pages River near the Murrurundi Gap, where not only the consignment of mail but all four coach horses had been swept away. He advised equal urgency in bridging the Peel River at the postal township of Tamworth, before the road ascended steeply to the tableland; and bridging the Macdonald River at Bendemeer on the tableland.12

Bennett’s advice extended from engineering to political economy. Like Martindale a firm advocate for letting work on contract, he stressed the need for successful tenderers to lodge securities to ensure their capacity. He grasped rural realities too, and was emphatic that contractors provide task work for capable day labourers so small selectors could

get the means of earning subsistence during the growth of their crops, and an opportunity of acquiring the necessary skill and capital to enable them ultimately to compete for contracts.

Though Bennett cited the success of the contract system in Ireland, in NSW it was more usually considered American, with the Maitland Mercury approving Martindale’s approach in 1858:

We have heard this contract system of maintaining roads in good order much praised, and its working in the United States alleged to be efficient and excellent… Perhaps some of the many intelligent Americans now living in the district will advise.13

But the most pressing problem was finding competent builders.

Martindale and Bennett worked closely together and were in accord on many key matters. The two men were the same age, though as an Army engineer recruited directly from London, Martindale’s had been a more direct and usual path into colonial public works. Everything was experimental, and uncertain, in these formative years of responsible government.

With the new Public Works role of Roads Engineer in place only two months, the Minister, John Robertson, was challenged in the Legislative Assembly by his predecessor with the argument that ‘the gentleman Bennett’ should also be charged with superintending the road surveyors on all three main routes.14 As well as Bennett’s overall responsibility for the routes, construction and maintenance of the main roads, from January 1859 Martindale’s reports state that ‘bridges were designed by the Engineer for Roads, Mr Bennett, CE’, with ten major bridges completed that year and 20 more underway. Of these seven were on the main northern road, three on the main western road, and ten on the main southern road.

The completed bridges comprised six on the main western road and four on the main southern road. Only two of these ten were timber truss bridges, over Cox’s River (see Figure 3.3a) and Junction Creek, but of the twenty large bridges under construction eight were timber trusses: at Falbrook (now Camberwell) and at the Pages River on the northern road; on the southern road at Berrima, Camden, and Jones Creek between Gundagai and Junee; on the western road at Ropes Creek between Parramatta and Penrith, and at Gosling Creek between Bathurst and Orange.

The eighth timber truss was at Albury on the Murray River, the Colony’s southern border. Two of the twenty in progress were the laminated arches being built over the Murrumbidgee River at Wagga Wagga and over the Peel River at Tamworth.15

Bennett described the Cox’s River Bridge as

a queen truss timber bridge on piers, with stone bases and wooden superstructure of two spans of 63 feet, and two of 20 feet each; the roadway is 12 feet wide and six feet above flood level; the total length is 170 feet [51.8 m].

Gosling Creek was based on a king truss, with all the others based on the queen truss. Bennett explained his design in Martindale’s final report in 1860:

For trussed bridges, the simple queen truss with iron suspension rods, in spans of from 50 to 90 feet [15 to 27 m], has been used, as giving the greatest headway and requiring least workmanship. When the headway had not been limited, a modification of this truss with radiating principals has been adopted, with the tie beam passing between the principals; it has been used in spans of from 60 to 100 feet [18 to 31 m], and the laminated arch has been applied in spans of the same dimensions, in some special cases where timber large enough for trusses could not be obtained.16

As Bennett had to train any assistant, he would have done his own calculations for the many bridge plans he drew up in 1859. The shortage of capable builders persisted for at least another decade and getting adequate tenders delayed construction at the Pages River, Albury, Camden, Berrima and Picton bridges, which were not completed until 1861. At Vacy Bridge over the Paterson River at Clark’s Crossing, the tender was let in May 1859 but work stopped when local contractor Stephen Stanbridge failed. The bridge was completed at the end of 1860, just before severe January floods caused major damage when the Paterson River rose nearly forty feet.17

Two of Bennett’s 1859 timber truss plans for bridges on the main northern road show his experimentation with the American truss design patented by William Howe in 1850, discussed in Chapter 2. After tenders were first called for the bridge at Falbrook (later Camberwell), between Singleton and Muswellbrook, Bennett altered the design to make the bridge longer and higher. While it looks similar to his Howe Truss plan for the Vacy bridge on the Paterson River (which seems not to have been built), at Falbrook there were distinct design elements that can be read as the step from the United States Howe Truss, towards the Australian Bennett Truss.18

The Falbrook Bridge made history not for its key design innovation, but as possibly the only colonial bridge damaged in a gunpowder plot. One night in September 1861, the longitudinal timbers were ‘severely injured’ when an unseen hand detonated gunpowder charges surreptitiously laid along the deck.

Though local press reports complained that the alignment approach required a sharp turn onto the ‘absurd narrow roadway’ of the bridge, at 12’ 9” (3.89 m) this roadway was wider, by just a body-width, than Bennett’s other contemporary bridges. If this were a Guy Fawkes-style protest it was equally ineffective, with the repaired bridge in service until 1894. But six years after the gunpowder protest, tragedy tested the allegations when a teamster was fatally injured, jammed between the framework of the bridge and his laden dray, as his horses continued to haul it across.19

Strategies for systematic roads development by Martindale and his Roads Engineer were constantly frustrated, both by the new methods of allocating funds and the government policy for roads to serve railways. At the end of 1860, Martindale concluded his final report by repeating his recommendations for ‘an entire change of the present system of expenditure’ before resigning on 20 November. Two weeks later, Bennett tendered his resignation too.20

On 14 January 1861 Bennett joined Mary and Ben Martindale and their three children aboard the La Hogue at Sydney’s Circular Quay. Government ministers joined officials, staff and friends gathered at the wharf in hearty cheers for the two men and for Mary Martindale. The farewell did not end there, as colleagues had hired the paddle-steamer Herald for the occasion and escorted the ship down the Harbour, crowding the decks in a rousing send-off.

When the La Hogue reached London at the end of April, both men had engagements. Martindale resumed his military engineering career in London, but Bennett’s engagement was to fellow passenger Agnes Hays, returning to her New York home. The Hays family had migrated there from London in the 1840s; a decade later three teenage sons had left home for the colonial goldfields and Agnes’ mother had despatched her daughter to NSW for firsthand news of her younger brothers.21

Bennett’s search for a secure professional post found him a few months later booking a passage back to NSW on the sailing ship Damascus, to become the Colony’s new Commissioner and Engineer for Roads and Bridges. His and Martindale’s former positions had been unsuccessfully diverted to their road superintendent William Collett and clerk of works Alexander Beazley, with Harbours and Rivers chief engineer EO Moriarty having to take over from Collett until Bennett arrived in March 1862. That November, Agnes Hays and Bennett were married, with a house at 320 Pitt Street Redfern their first home.22

In 1865, shortly before the birth of their third child, the Bennetts moved to 55 Shellcove Road Neutral Bay, to a house Bennett named ‘Honda’ in memory of the picturesque haven on the Magdalena River that had been his base in British Colombia a decade before. With a buggy ride to Blues Point, Bennett could commute to the Roads and Bridges Branch offices at 124-28 Phillip Street on the very same paddle- steamer Herald, then plying as a Harbour ferry.

Reporting in March 1865, Bennett pointed out the many ways roads policy had deviated from the priorities he and Martindale had set. Their strategy put bridging of rivers and creeks first, to reduce interruptions to mail and other traffic; then to improve the most difficult of the mountain roads and those in swampy areas; thirdly, to survey permanent lines of main roads and form and surface these and any ‘heavily trafficked’ areas near settlements to create a continuous road network, enabling economical and efficient maintenance.23

Bennett now added four roads of ‘colonial importance’ to the three ‘Great Roads’ enacted in 1858, seeking funds for routes from the Clarence River port of Grafton up to Glen Innes and Armidale on the northern tableland; in the west from Molong to Bourke; in the south from Wagga Wagga to Deniliquin and then to the border of South Australia; and from Batemans Bay on the south coast up to Braidwood. With these roads Bennett finished the foundation of the NSW highway system.24

Despite chronic deficiencies in resources, Bennett reported that by 1865 new bridges and improved roads on the western and southern roads meant ‘the mails have been able to travel at night on many roads… and that they can travel much faster on the greater portion of the road, and are not exposed to so many accidents’.

In this key report Bennett laid out the increasing transport demands, his technical solutions, and their limitations. His frustration was evident:

It is impossible to estimate the extent of the injury caused by the enormous weight carried on narrow wheeled vehicles, drawn by long strings of horses or bullocks, yoked up, half independent of the driver’s control, and following in the same track, making no attempt to avoid a soft place, until by tearing and dragging out, a small rut is enlarged into a dangerous bog.

With no engineering solution and legislation flaunted, Bennett urged the regulations finally introduced in 1870.

Seemingly ‘every improvement in the road [is] followed by a corresponding increase in the weights carried’. Loads had doubled since 1862, and from 1865 he increased the width of bridge roadways to 16 feet (5 m).25 It was a change that might have saved the life of the Falbrook drayman.

Bennett used the laminated arch design for the last time to bridge the Macdonald River at Bendemeer, one of the bridges he had recommended as urgent in 1858. Completed in 1865, this bridge carried traffic on the main northern road for forty years until it was replaced with a timber truss bridge (see Figure 3.3b and Figure 3.29).

Floods were the most savage enemy of bridges, especially without flood data. The 1852 record flood heights exceeded just ten years later, Bennett sought to raise the height of decking by increasing the length of bridge spans. He reported that:

from want of full experience of the capabilities of the indigenous timber applied to intricate framing, and from the very shrinkage and warping which occurs if not seasoned, spans exceeding 100 feet [30.5 m] have not been used; but a design for large spans, on the principle of the McCallum truss, so extensively used with the softer and lighter timber in the United States, has been under consideration for some time, and will be applied when opportunity offers.26

American railroad engineer Daniel McCallum had taken out patents for his fixed arch truss in the 1850s, when Americans flocking to the Australian goldfields increased colonists’ awareness of news and events in the United States.27 Bennett of course had the particular advantage of a wife and brothers-in-law raised in New York City, all abreast of news and events there. He also had a direct professional source, as his membership of the British Institute of Civil Engineers was approved in February 1864 and the current issue of the ICE Proceedings carried an article noting that in the United States ‘Timber-bridge building has become an especial branch of Engineering’, with McCallum’s ‘the most eminent’ of the specialist firms and his truss ‘now probably in more general use than any other bridge’.28

Bennett took his opportunity to employ the McCallum Truss in 1866, in designing a bridge for a steep site across the Lachlan River at Cowra with three 130 feet (39.6 m) major spans. Work started in March 1867, but was delayed by the failure of the first contractor and then for completion of the Gundagai Bridge, so its builder could take over the Cowra works. Completed in January 1870, the Cowra Bridge was proclaimed the largest timber bridge in the Australian colonies. Set 48 feet (14.6 m) above the river’s summer level, it withstood autumn flooding that brought the river over the decking and piled ‘hundreds of tonnes’ of debris against the trusses and over the roadway and was hailed as a ‘noble piece of engineering skill and excellent workmanship’.29

But there were critics aplenty as flood records were set anew, as in the winter of 1870 when severe flooding damaged many bridges and a bitingly sarcastic open letter from an anonymous Goulburn identity was publicised. Bennett reported:

I am only directly responsible for the failure of one of these structures – the high-level bridge at Marsden’s Crossing, which was destroyed by the overwhelming and unprecedented flood of April 26th, which also… [removed] the platform of a 40 ft. span bridge off the piers… depositing it intact some chains downstream. Much of the damage was caused by the accumulation of timber against the bridges…30

Bennett had designed Goulburn’s Marsdens Crossing Bridge† over the Wollondilly River with a timber truss span of 90 feet (27.4 m) to put the deck three feet above the 1852 flood level, but in 1870 the river reached four feet (1.2 m) above the girders of the three-year-old bridge.31

By 1876, when Bennett’s second McCallum Truss bridge, across the Richmond River at Casino (see Figure 3.4a), was completed the McCallum timber trusses were no longer used in the United States, where iron was increasingly used in bridge building.32

Bennett’s 1871 defence of the flood performance of his bridges included the Colony’s first iron road bridge, the Prince Alfred Bridge at Gundagai:

I would point out that at Gundagai the bridge and approaches were built to clear the highest level given of the flood of 1853 – a foot higher than the disastrous flood of 1852 – and that the flood of April last was within 1 foot 6 inches [0.46 m] of that height at Gundagai.33

The Sydney foundry of PN Russell won the contract for fabrication of the next iron road bridge, the replacement for Weaver’s 1855 laminated arch Denison Bridge at Bathurst that had been ‘carried away bodily one mile down the river’ in winter floods of 1867.

Casting of the piers was underway by the end of that year, with Bennett’s office still determining their siting.

Bennett designed the piers and girders, while Gustavus Morell developed the drawings and the calculations for the superstructure under Bennett’s direction. A French architect-engineer, Morell had joined the Colonial Architect’s Office in 1863 when he was brought to NSW for his expertise on defence structures. Even before construction began, readers could anticipate the innovations, thanks to the Sydney Morning Herald’s explanation of the design with:

three spans of 110 feet [ 33.5m] each of triangular girder, on the newest principle, being an improvement on a truss known in the United States… in which the greatest care is taken to make the centre of stress of each member coincident with its centre of gravity. The roadway will be 22 feet wide with two external footways of 4 feet each, or a width of 35 feet [10.7 m] over all, the flooring joists to be of iron and. arranged so as to act as horizontal diagonal bracing.36

As well as the first use in the Colony of the Pratt Truss, Bennett’s girders were reportedly ‘of a construction new in Europe’ (see Figure 3.7).37

Bennett’s early experiments with iron are particularly interesting, given the limits of its availability and his tight budget. Iron bridges he designed with Gustavus Morell ranged from the swing bridge over the Murrumbidgee at Hay in the Riverina, to the bridge across the Orara River on Bennett’s new Newton Boyd road linking Grafton with the New England Tableland. For the Hay bridge, Morell designed a lattice girder span supporting timber decking, while the Orara River bridge trusses have the lattice variation of the Warren Truss. For this bridge Bennett designed single ‘windowed’ piers rather than paired piers, to minimise the piling of debris in floods. Cast as sets of cylinders at Mort’s Foundry in Sydney’s Balmain, these were ‘the heaviest work yet done in the colonies’. Both Bawdens Bridge over the Orara River (named for the local MLA) and the Hay Bridge were opened in 1874 (see Figures 3.8 & 3.9).

But six years later even the busy Sydney firm of PN Russell had closed down, reputedly rather than accede to workers’ action for an 8-hour day. The firm’s principal, Peter Russell, became even better known as the chief founder of the Engineering Association of NSW in 1870, with William Bennett and Gustavus Morell among the founding members, and as the benefactor for the new school of engineering at the University of Sydney in 1882.40

With reduced civil service wages threatened in 1872, Premier Henry Parkes supported an increase for the hardworking Bennett, ‘one of the ablest officers in the government service’. Then in office for a decade, Bennett’s increased annual salary of £1000 was still less than Whitton’s.41 His team of bridge engineers also increased, with two assistant engineers by 1876, Frederick Wells and John Daniells, the latter designing iron lift bridges for the Murrumbidgee and Darling Rivers.42

That September Bennett took on his first engineering cadet, Sydney- born and educated Percy Allan. With patronage still the prime factor in public service preferment, the 17-year-old had the advantage of his father’s position as deputy head of the Colonial Secretary’s department – Maxwell Rennie Allan’s 30-year career, following his own father’s civil service dating back to Governor Macquarie’s administration, had ended with his death in 1879.

Bennett’s Roads Branch had nearly 900 employees in June 1879, when young British-qualified engineer John McDonald was appointed in London to take charge of the wrought ironwork ordered for the lattice truss bridge at Gladesville over the Parramatta River. At 23, McDonald had studied civil engineering at King’s College London and then completed articles at the Greenwich ironworks of Appleby Bros., where he worked on the design and fabrication for the Gladesville order.

From his arrival in August 1879 McDonald was responsible for erection of the superstructure of the Gladesville Bridge, a more complex project than any other lattice truss bridge in the Colony. With its moveable swing span enabling tall vessels to pass underneath, the Gladesville Bridge was hailed as a signal achievement on completion in February 1881 (see Figure 3.11). McDonald was elected a Member of the Institution of Civil Engineers that year, his supporters including Bennett, Whitton, and WH Warren, as well as John Fowler in Britain.

That winter Bennett abruptly left work and sailed for England on 18 June 1881, four days after he received news of his wife’s sudden death from smallpox. He returned to Sydney with the children on 17 October, when they moved back into their home ‘Honda’ at Neutral Bay in Sydney. Eighteen months later Bennett remarried, and with Sarah Darling, the sister of his daughters’ teacher at Dulwich, had two more children.45

Warren’s reports warmly acknowledged McDonald’s contributions to his work and at a meeting of the Royal Society of NSW, he also defended McDonald’s design for composite trusses for a new bridge at Cowra, with McDonald’s young colleague Harvey Dare among those questioning the calculations. Replacing Bennett’s 1870 McCallum Truss bridge with ‘entirely a new design by the department’, the McDonald Truss bridge over the Lachlan River had a span of 160 feet (49 m).50 (see Figure 3.15)

McDonald’s contribution to the discussion of Warren’s presentation to the Royal Society in 1886 provided a rare published example of his scientific reporting, with his explanation of how he calculated his ‘compound beam’ strength. With records of McDonald’s work so rare, his surviving calculation books are key evidence of his methodical analysis and appreciation of materials. These books also carefully record each experiment on the strength of Australian timbers, noting when and where the tests were performed, as well as the methods and results.

Bennett’s memorials were everywhere across NSW. His Branch had built almost 10, 000 miles of main roads with forty miles of bridges, including almost 150 Bennett Truss timber bridges, many then Australia’s largest bridges. Hailed as ‘a man of singular ability, prodigious energy, and untiring industry’, accolades appeared in country as well as city newspapers, honouring Bennett’s work over three decades. Tributes from his staff are specially moving, like young road superintendent Robert Jones’ heartfelt:

I cannot finish this report without mentioning my feelings of deep regret at the death of our Good Old Chief, Mr Bennett. A giant’s labour is ended, and we can now only mourn the loss of one who ever tried to be just and kind to his officers and who gave almost superhuman labour to his Country.54

Bennett had headed an establishment of 168 officers and now three positions replaced his, the new chief engineers Robert Hickson for roads, John McDonald for bridges, and from 1893 Percy Scarr for a separate Sewerage Construction Branch.

As the new chief McDonald continued to explore metal construction, designing two steel beam bridges for Sydney sites, Unwin Bridge at Tempe and a’Becketts Creek Bridge at Parramatta. Completed in 1891, they are routine in form, but mark a very early use of steel in NSW with the first local steelworks not established for another twenty years.

Like de Burgh the previous year, Allan was now able to take a professional step forward with McDonald nominating him to the ICE, and a personal one, marriage to his fiancée Alice Trangmar in November 1890. These were not auspicious times for newlyweds, with the onset of economic depression affecting lives both public and private. In the first year of the de Burghs’ marriage all civil service salaries were cut by 10% and a retrenchment program put in place. The couple were a fortunate exception, with a legacy to Constance de Burgh enabling them to build a grander house next to their cottage at 72 Station Street Meadowbank, moving in with their three children during 1893 (see Figure 3.21). With his position secure, Harvey Dare and his fiancée Constance Tindale married in October 1895, at her hometown of Rylstone, on the Cudgegong River.

Among the casualties of the drastic decrease in imports of iron components from 1891 were plans McDonald had already prepared to a high level of detail, for a 147 feet (44.8 m) iron arch bridge for Sydney’s Lane Cove River costing £10,000 and an even grander 180 feet (54.9 m) iron arch to bridge Stonequarry Creek at Picton. Both sites were bridged much later with timber trusses, as was the Murrumbidgee River at Wagga Wagga, for which McDonald had proposed a design using light iron girders.

McDonald designed in iron wherever he could and it was Percy Allan who succeeded Bennett as the advocate of timber. Allan’s expertise in timber bridge design might have saved him and his team in the Drafting Office, with economy an inflexible regime in the early 1890s.

By the time the economy began to ease in 1894, 246 staff had been retrenched from the Department of Public Works, with no major reduction in the Roads and Bridges establishment, the main field for unemployment relief works.61 But among those retrenched was the Branch’s chief bridge engineer, John McDonald, despite his seniority, the ample proof of his ability and that at 37, he was just approaching the prime of his working life. The only light on this decision is Harvey Dare’s recollection of his chief:

He was an able man, and always good to me, but he had a sardonic trait in his character, which brought him into conflict with some of the other Departmental Heads, who in the end were too strong for him…62

McDonald had crossed the world to begin his engineering career in NSW and his retrenchment seemed to reopen professional possibilities. A member of the American Society of Civil Engineering since 1886, he spent six months in the United States in 1894 promoting his patented expansion roller, winning several exhibition awards. Fremantle was his next base when he took a post with the Western Australian Public Works Department in 1895, resigning from the position in October 1898. By 1902 he was in Rhodesia (now Zimbabwe) working as a mine surveyor, and from 1903 was deputy town engineer in Johannesburg. The poor health of his wife Marion, his ‘beloved friend and companion’ brought the couple back to Perth in 1907, with McDonald soon engaged on the State’s water conservation works. In 1912 they moved to New Zealand, where he spent five years as engineer and secretary to the Gisborne Harbour Board. After Marion’s death in February 1917, at 65 McDonald’s own ill-health and perhaps also his fractious disposition led to his dismissal. His skill and experience gained him a position as engineer for the local Gisborne Council and in 1919 he remarried, continuing to work for the Council as consulting engineer into his 70s. It was the talented and unsung engineer’s last post; in deteriorating health he took his own life on 4 June 1930.63

The Allan Truss 1894-1929

From Harvey Dare’s second year in the Drawing Office, Allan had him working on a new timber truss bridge design. The new Allan Truss was designed with the advantages of accumulated data from Warren’s timber analyses and more than 35 years of empirical experience with timber truss bridge technology.

The following year eight of the new Allan Truss bridges were opened. The first, on 27 July 1894, linked the goldmining township of Yalwal on Yarramunmun Creek to Sassafras, on the ‘Wool Road’ down to Nowra. Just three days later, the official opening of the Stoney Creek Bridge on the south coast road between Bodalla and Bega was celebrated, and on 13 August the opening of Glennies Creek Bridge at Camberwell in the Hunter Valley (see Figure 3.22). This bridge replaced the deteriorated 1861 Falbrook Bridge. The new design enabled lighter construction in hardwood or composite steel and timber, using shorter lengths of timber which were much easier to obtain and manoeuvre. The new trusses were in standard lengths of 70, 90 and 110 feet (21, 27 and 33.5 m), so that from 1895 prepared timber was ordered by tender and stocked.64

Allan’s evidence for timber included the 1861 Bennett Truss bridge across the Murray River at Albury, in service for 37 years before needing the replacement Allan designed. Allan also used this overhead-braced design for the Wagga Wagga Bridge completed in 1895 and compared the cost with a wrought iron truss bridge of the type McDonald had favoured. He was undeterred when his audience questioned his costings based on expensive local iron, nor by timber’s higher maintenance costs. Allan repeated this defence of his costings in a paper published by the ICE in 1897, but his advocacy of timber had its best evidence in the performance of bridges like one on the drawing board that year, for Kempsey. Completed in 1900, the bridge was in operation for sixty years (see Figure 3.23).67

As supervising engineer for a decade from 1891, de Burgh’s responsibilities included coordinating the resident engineers and liaison with local communities. He oversaw construction of some eleven major bridges, from the Murray River in the south to the Tweed River in the north, and from the coastal rivers west to the Darling River. This role also associated de Burgh with several singular bridges, like the 1896 limestone arch bridge at the entrance to Jenolan Caves’ Grand Arch that became known locally as ‘de Burgh’s Limestone Bridge’ (see Figure 3.24).

He was involved in planning two substantial suspension bridges, the 1898 Hampden Bridge on the descent from the southern tableland through Kangaroo Valley and the 1903 Maldon suspension bridge over the Nepean River at Picton. The American Pratt trusses stiffening the Hampden Bridge’s 252 feet (7.68 m) span make this a notable precursor to de Burgh’s free-standing timber truss bridges. In contrast, Gothic masonry towers supporting the metal suspension cables make the Hampden Bridge a singular landmark in the Kangaroo Valley.68

Directed by its site, the design of Maldon Bridge (see Figure 3.25) included steel Warren trusses and

a stiffened suspension structure of an uncommon type, in as much as the main cables after leaving the towers are carried upwards to an anchorage in the sandstone cliff above the bridge instead of downwards as is usually the case.69

In 1900 Allan was transferred to the PWD’s Harbours and Rivers Branch to oversee construction of the bridges, during which he was made a Member of the ICE. Innovations included Pyrmont Bridge’s electrically-driven moveable span, the electricity supplied from the new Ultimo Powerhouse nearby. Opening the Pyrmont Bridge on 28 June 1902, State Governor Sir Henry Rawson observed it outdid London’s Tower Bridge, with a larger deck area and an opening time of 38 seconds compared with 52 seconds.73

The de Burgh Truss 1900-1905

In March 1901 de Burgh was promoted to chief bridge engineer and as soon as the drafting tables were cleared of the Pyrmont and Glebe Island bridge work, he had Bradfield and Dare developing an improved timber truss. Drawing on the Pratt Truss, the new design followed McDonald’s use of a metal bottom chord, as well as incorporating features of the Allan Truss such as pairing timber members for ease of maintenance. The Queens Bridge over the Queanbeyan River, opened in March 1900, was the first of the new design now known as the de Burgh Truss (see Figure 3.28).74

Bradfield took up the design challenge with four record- breaking 153 feet (46.6 m.) trusses for the bridge over the Macleay River at Kempsey, even taking his theodolite to local stands of ironbark to confirm supply of the great lengths needed. But Dare outstripped him, with a single Pratt Truss span of 165 feet (50.3 m.) for the bridge over Sydney’s Lane Cove River. This cost a third of McDonald’s 1891 iron arch design, and gave Bradfield renewed opportunity for jokes about his lost bet with Dare.

Bradfield used an Allan Truss for the Kempsey Bridge, but the Lane Cove River bridge like the Queens Bridge, was a de Burgh Truss. The Kempsey Bridge, built of local ironbark and tallowwood, opened in April 1900 as the largest timber truss with a timber bottom chord in the Colony (see Figure 3.23 ), until February 1901 when the Lane Cove bridge was officially opened as the de Burgh Bridge, both the largest timber truss bridge and the first in the new State.75

In the recollection of the modest and unassuming Dare, he had designed the de Burgh Truss, and was indebted to de Burgh for assistance and advice.76 The first two de Burgh Truss bridges featured sloping end members, revised to verticals on the other eighteen of these bridges built. While it is difficult to identify de Burgh’s specific role in the creative output of his Drawing Office, like McDonald his inventive talents are evident elsewhere. An example is the method he devised in 1899 of using Monier concrete to protect submerged timber piles against teredo, the ‘termite of the sea’. The Monier casing was first used for the Cockle Creek Bridge south of Newcastle, completed in 1901. A successful substitution at about half the cost of cast iron, full Monier concrete piers were used at de Burgh’s 1904 Middle Falbrook bridge over Glennies Creek. For the 1902 Lansdowne Bridge at Goulburn, only the submerged portions of the piers were constructed from Monier concrete pipes, with the upper portions constructed as traditional timber piers.77 De Burgh won the first of his Telford Premiums for this technology, with the other in 1904 for his work on suspension bridge cabling.78

De Burgh’s transfer to LAB Wade’s Water Supply and Sewerage Branch in August 1903 and promotion to Chief Engineer for the new Branch of Harbours and Water Supply in 1908 involved him in construction of the Burrinjuck Dam for the State’s first major irrigation project. The reservoir built in 1908 for the construction railway, named Lake de Burgh, was Australia’s first reinforced-concrete thin arch dam. Burrinjuck Dam, completed twenty years later, was also designed by de Burgh.79

As chief engineer for water supply with the NSW Water Conservation and Irrigation Commission from its establishment in 1913 until his retirement in 1926, de Burgh was responsible for the design of the Chichester scheme for Newcastle and the Umberumberka scheme for Broken Hill. His many reports to the State government included his observations on hydro-electric schemes in 1919 and his comprehensive 1918 report on augmentation of Sydney’s water supply. Forecasting the population increase of Sydney and surrounding districts, he recommended accelerating construction of the Cordeaux Dam, with additional storage reservoirs on the Avon, Nepean and Warragamba rivers.

Their children grown, Ernest and Constance de Burgh had moved in 1913 to ‘Harlowen’, in Hopetoun Avenue in Sydney’s harbourside Vaucluse. A keen gardener, Constance created new gardens there, with her husband away no less often in his new position as the State’s chief engineer for water supply. De Burgh had also been responsible for investigating water sources for the nine sites proposed for the Federal capital city, with water supply the key to determining the borders finally enacted for the Federal Capital Territory in 1911.80 At the end of his long Public Works career, in 1921-25 de Burgh was a member of the Federal Capital Advisory Committee and involved in planning the water supply for the national capital. Despite his illness, his ‘unusual strength of personality’ came to the fore, with Committee secretary Charles Daley recalling de Burgh as ‘a most convincing exponent of his point of view, and a ruthless and logical examiner of every question before him’. De Burgh always retained the engaging charm evident in his first correspondence with Bennett. Daley observed that though

often a drastic critic in expression, at the same time he possessed that characteristic Irish wit and humour that removed the sting but left the logic. He was adept at dealing with politicians, and it was a delight to hear him giving advice, in a racy manner, to the ministers and many members of Parliament…81

Constance de Burgh enjoyed their many Canberra visits too, with keen interest in the growing garden city and the work of Charles Weston’s Yarralumla Nursery.

Allan’s Public Works career was also diverted into water supply and conservation. After completion of the Pyrmont and Glebe Island bridges in 1903, he was in England and France on a study tour of dam construction, returning to work on the design and construction of the Cataract Dam. From 1908 Alice and Percy Allan and their young sons lived in Newcastle, where Allan became the district’s first Chief Engineer for Public Works in 1911.82 After his leave on medical grounds in 1912, Director-General of Public Works Joseph Davis appointed Allan his assistant and the family moved into ‘Kerela’, their new house in Hunters Hill Sydney.

In 1917, Allan succeeded Robert Jones as Chief Engineer for National and Local Government Works, a role that brought him back to bridge-building. In 1923 he went to Melbourne to plan two new bridges across the Murray at Abbotsford and Gonn Crossing, at the joint expense of NSW and Victoria. From 1924 Allan had overall design responsibility for the Tom Ugly’s Bridge over the Georges River in Sydney, supervising construction until his retirement in March 1926.83

The Dare Truss 1905-36

With Allan no longer involved in timber bridge design from 1900, Harvey Dare headed a reduced Drawing Office of thirteen. Under de Burgh as chief bridge engineer for the next three years, first Dare and then Bradfield were designated ‘bridge computers’, developing the de Burgh Truss. The pair had the additional work of assessing international tenders for the proposed bridge over Sydney Harbour, until August 1902 when Dare had to take extended medical leave and Bradfield was in charge until February 1903. Back at work when de Burgh was transferred to Water Supply in August 1903, Dare then took charge of road bridge design.84

With plans for a bridge over the Macdonald River at Bendemeer on the drawing board, Dare was working on his own new truss design based not on the de Burgh Truss, but the Allan Truss. Aiming for simplicity and economy, Dare’s refinements included a metal Figure 3.29: The first Dare Truss bridge, the 1905 Bendemeer Bridge over the Macdonald River replaced the 1865 laminated arch bridge. The new bridge was in service for 80 years and remains today as a footbridge. Source: Roads and Maritime channel for the bottom chord and square truss panels, rather than Allan’s rectangular panels, to make the carpenters’ work easier. Dare explained the benefits of the truss design to the ICE in 1903:

The composite truss represents an economical and durable type of structure, erected without difficulty and easily renewed, since the bottom chord is of a permanent nature and the timber members, which required renewal at intervals of about 30 years, are all in compression, and can be easily replaced.”85

These were very difficult years for Dare, with overwork, illness, and then in 1904 the death of 32-year- old Constance Dare, leaving him to raise their six-year-old daughter Marion Constance. At the same time his work responsibilities multiplied when retrenchment of 469 PWD staff led to amalgamation of all four PWD engineering drawing offices in 1904, with Dare in charge.

Opened on 29 September 1905, the Bendemeer Bridge (see Figure 3.29) replaced Bennett’s 1865 laminated arch bridge and was the first of more than forty Dare Truss bridges built over the next thirty years. By 1905 there were 3, 831 PWD bridges in NSW, a census taken when the Local Government Act 1906 provided for local councils to take over management and maintenance of roads and bridges. The exceptions were 256 major bridges classified ‘national works’, the responsibility of a new Local Government Branch of the PWD under Robert Jones as chief engineer.

The first dozen Dare Truss bridges were built while Dare was head of the amalgamated PWD Engineering Drawing Office. With ironwork inspection added to his duties, in 1908 he supervised conversion of Penrith’s Victoria Bridge from a railway to a road bridge. Dare’s ‘cardioid’ lift mechanism was used for eight bascule bridges in NSW. Thirty years later, Dare wrote wryly that he had ‘worked like a galley slave’ in his six years in charge of both road bridge design and the Departmental drawing office. But he still regularly presented his work to the profession, from the newest students at the University of Sydney Engineering Society to the most senior members of the Institution of Civil Engineers in Britain.86

Then in 1910, Dare followed both Allan and de Burgh with a transfer to water supply under LAB Wade. He worked on planning the Murrumbidgee Irrigation Scheme and the Upper Nepean scheme for Sydney’s water supply with three dams, the Cordeaux, Avon and Nepean. Dare was Chief Engineer for the State’s new Water Conservation and Irrigation Commission in 1913, and then Commissioner from 1916.

Dare’s role in establishing the Coomealla Irrigation Area near Mildura, a soldier-settlement scheme, was honoured in 1922 when its town was named ‘Dareton’. Dare represented NSW on the River Murray Commission in 1923, oversaw the completion of Burrinjuck Dam and was heavily involved in the development of Wyangala Dam.87

The Dare Truss was the last step in the design process for timber truss bridges in NSW begun by William Weaver in 1854. Without other trained engineers to assist them, Weaver and Bennett created the form of their bridges and as well, calculated the functioning strength of every part. It is unclear when Bennett first had professional assistance, but for a decade from 1869 he partnered with the Colonial Architect’s Office’s Gustavus Morell on the design of iron bridges. Percy Allan was Bennett’s first cadet when he joined the Bridges Section in 1878 and he certainly became Bennett’s most prominent trainee. From 1876 Bennett had two assistant engineers and in 1881 qualified engineer William Warren joined the Branch, but left the following year to found the Engineering School at the University of Sydney.

In 1879 the appointment of John McDonald gave Bennett a talented design engineer for metal bridges and for moveable span bridges, with McDonald soon applying his ingenuity to timber truss design. Like Bennett, McDonald was expert at calculating stress and innovative in responding to problems.

By his retirement in 1889, Bennett’s Roads and Bridges Branch Drawing Office was an incubator for design engineers and a hothouse of calculation. Throughout the 1890s, some of the ‘stress men’, the engineers responsible for the calculations for each specific site, can be identified in the hive of productivity that was the Drawing Office. There was even a name for the position, with Dare, his friend Jack Bradfield and other new engineering graduates like JW Roberts among those designated ‘Bridge Computer’.

Dare’s account of his part in the creation of both the Allan Truss and the de Burgh Truss shows the key contribution of the diligent ‘stress man’. Bridge design is conceived not only as an idea, but as a form that must function.

Unlike Bennett, Allan and Dare were not involved when most of the bridges recognised as theirs were constructed. Percy Allan had left the Branch by 1900 and most of the Allan Truss bridges were built between then and 1929. However, his signature appears on various of these plans and , as Ian Jack reveals in Chapter 5 ‘People, places and bridges’, the year before his retirement Allan was entertainingly prominent at the opening of the Allan Truss Tooleybuc Bridge in 1925. Similarly, Dare’s transfer from Bridges in 1910 meant he was not involved with any of the Dare Truss bridges built over the next 26 years. His standard designs for 70’, 91’ and 104’ trusses could be used in different locations, needing only site-specific calculations like deck height and the design of piers and abutments. Adaptability was part of the design creativity of the Allan Truss and the Dare Truss, enabling each to be applied at a wide variety of sites, over some thirty years.

Design creativity is the elegant mystery at the heart of the stories of the design engineers sketched in this chapter, not least because the identities of their co-designers are unknown. The search for the ‘stress men’ responsible for the timber truss bridges of NSW is ongoing, like the design process itself.