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Hamilton Bridge 1909-1963.

Hamilton Bridge. Half elevation / half longitudinal section. Part of a drawing signed by Monash on 14 March 1909 for submission with the tender. At that stage it showed no details of the reinforcement. It was later transformed into a working drawing with the addition of reinforcement, and was initialled by two of Monash's assistant engineers: J A Laing and P T Fairway. The above sketch is based on a photocopy of the drawing, courtesy of VicRoads.

Introduction

According to VicRoads this bridge carried Mount Napier Road over Grange Burn Creek, on the outskirts of the Borough of Hamilton, and it was replaced by a prestressed slab bridge in 1963. By 1908, Monash had designed and built a dozen or so reinforced concrete T-girder bridges; so from a technical viewpoint, the Hamilton bridge is unremarkable. However, a dispute between one of the Shire Councillors and the construction foreman gave Monash a chance to exercise his diplomatic skills.

Preliminaries

Frank Hammond, Engineer and Town Clerk of Hamilton, first contacted Monash in June 1908 to enquire about the use of reinforced concrete. Monash asked one of his assistant engineers, H G Jenkinson to prepare an initial estimate of cost for a bridge with three spans of about 25 feet (7.62m). The piers should be 18" thick (457mm), and the five main girders similar to those of the Lancefield Bridge. The abutment and wing walls should be based on those of the Emu Creek Bridge.

Hammond had also asked whether reinforced concrete would be suitable for a new Town Hall for Hamilton, but was told that the material was best suited to structures subjected to "heavy stresses".

Monash calculated that competitors offering a timber bridge would bid about £588. His own price for reinforced concrete would be £630, made up of £465 basic cost plus £165 for profit and contingencies. On other occasions he had used a 'present value' calculation to show that the extra capital cost of a concrete bridge would be repaid by savings in long-term maintenance and replacement costs; but on this occasion he argued that the road width could be reduced to 18 feet and that the deck could be situated two feet lower than planned. These modifications would save £28 and £44 respectively, permitting a tender price of £558, i.e. £30 less than timber.

When Hammond's specification became available, Monash was unhappy with the "very stringent" financial conditions imposed; and the stipulation that the Contractor pay for a load test. He protested: "Although we have built upwards of 60 bridges we have never on any single occasion been called upon to carry out the test ourselves." The specified load, a heavy traction engine pulling three loaded trucks of 14 tons, was ridiculous. Hammond replied that such loads really did occur in the Hamilton district; but the test could be omitted if RCMPC provided a solid guarantee.

In his tally of 60 bridges Monash was including steel, timber, and concrete arch bridges.

The Tender

RCMPC's formal tender, submitted on 14 March 1909, offered three alternatives:

the bridge as originally called for:£792
with a reduced width of 18 feet:£764
with the deck also lowered two feet:£720.

Iron handrails were an optional extra, at £32.

Monash asked George Kermode of the Public Works Department, which was responsible for vetting the Council's decision, to encourage the councillors to adopt 'permanent construction'. He explained that the price for concrete was unusually high compared with timber because of the stringent financial conditions.

With slight refinements to the design, the price came down to £780-14-0. This was accepted by Council on 26 March, and PWD approval reached Hammond on 15 May. Details of the reinforcement were now added to produce RCMPC's working drawing.

Work commences

Monash was keen to push on with the foundations before the winter rains came, and ordered work to commence about 30 April 1909. The contract documents were not formally completed until 18 May. RCMPC's foreman for the job was E Samson. Construction of the foundations proceeded smoothly, and by 24 May work was safely above the highest recorded level of past floods.

Foreman versus Councillor

About this time one of the Borough Councillors, William Moore, who happened to be a builder, decided to visit the site and made adverse comments about the quality of the work. According to the foreman, he was "abusive and insulting". Samson riposted that "only fools and children should look at work half finished". This did nothing to improve matters. Samson ordered Moore to leave the site, and when the Councillor refused there was a scuffle in which Moore was tipped off the planks and into the creek.

Moore said he had seen spawls being placed in the abutments directly in contact with each other, with just a little concrete thrown over them.

Monash learned of the problem on 25 May, when he received a telegram from Hammond: "Foreman at bridge has insulted a Councillor seriously, must apologise immediately or be withdrawn". Monash replied: "This Company strongly discountenances any discourtesy by its employees to any Councillor, and regrets complaint, but questions justice arbitrarily dismissing Foreman without full particulars. Please write fully." To Samson he telegrammed: "Engineer wires you have seriously insulted Councillor and insists you apologise or be withdrawn. Wire and write fully. Meanwhile remember Company's interests supreme, and we expect you sink personal feelings."

Moore was convinced that Samson had been trying to prevent him from seeing work that was "not fit for inspection". Hammond appealed to Monash for rapid action to prevent a deterioration in relations between the Borough and RCMPC.

Monash argued that Moore had had no right to enter the site. "Work of this kind would be quite intolerable if every Councillor who thought he knew something about the work had the right to come on the job in a hectoring or bullying spirit, finding fault". However, he was mainly concerned to deflect the demand for Samson's removal. "If one of the Councillors has taken up the role of unwarrantably mixing himself up with matters which are the official duty of the Engineer, I do not see that it would be fair and just for that Councillor to revenge himself by depriving one of the workmen of his means of livelihood. It could certainly mean that if the Foreman were taken away from work, he would be dismissed from our employment." And in a later letter: "It would really seem to me an act of gross injustice to punish a loyal and competent servant of the Company for what was, at worst, some want of judgement in a difficult position, into which he was forced by the imprudent action of another man." Monash's third concern was to defend the reputation of his firm. "As regards the suggestion that any improper work was being done, this is simply preposterous, as the reputation of this Company and its employees stands too high in this State for anyone in Mr Moore's position to successfully assail it."

Hammond agreed with Monash that the whole matter was "childish" and that the best policy was to try to calm everyone down and hope that it would blow over. He pointed out that, while councillors should not interfere with work, there was indeed a clause in the Hamilton contract that gave them right to enter the site. He had inserted it in order to encourage them to take an interest in the still unfamiliar technique.

The Council expected a representative of RCMPC to travel to Hamilton to consult on the dispute. Samson, for his part, also expected someone to come from head office to defend him. However, Monash and his assistants were extremely busy at this time, and no-one appeared.

During construction of the Hamilton bridge, Monash attended the Easter military camp; made at least four visits to the Adelaide office; and coped with fallout from the destruction of the partly-completed Glenelg Breakwater.

While defending Samson in letters to the Council and Hammond, Monash had been encouraging his foreman to adopt a conciliatory attitude. "Taking the very best view of the matter" it was possible that Moore had been interfering and criticising, and that Samson in anger had said something offensive, perhaps not aware of Moore's position. "However, whatever were the facts, you must realise that it is not to this Company's interests to have any rows with its customers. Between gentlemen, if one man in a state of anger offends another, it is only manly and courteous to express regret and apologise when matters have cooled down. In a matter of this kind, the least said is soonest mended, and if you are at all heckled or worried by the Councillors, your best plan is to say nothing at all, but simply complain to me. These Councillors have considerable powers, although they may understand nothing about our work, and consequently it is not prudent to make an enemy of any of them."

Gradually, feelings subsided. Hammond reported that Moore, who had spoken of suing Samson, was now unlikely to do so. He would probably be content with an apology, and had acknowledged that he had had no right to interfere directly in the work. Monash was able to tell Samson: "the Council is prepared to overlook all heated language that passed between you and Mr Moore, but can't overlook your act in tipping Mr Moore off the plank, which, of course, is a technical assault, for which you may possibly be liable to a prosecution. However grave the provocation, the law does not allow even a technical assault. The Council will be satisfied, and will regard the matter as closed, if you will express regret to the Council for this particular action. You can easily do this, saying that you felt you had received great provocation, and that in the heat of the moment you did something for which you are now sorry, and desire to apologise for. I think we can reasonably ask you to do this, so as to establish peaceful relations again."

Work continues

In the meantime, Hammond had continued to discuss progress on the job. His use of the pronoun "we" suggests that, as often seems to have happened, the municipal engineer was acting as honorary site engineer. "We" were using mainly ironstone gravel from the creek for mixing concrete, even though crushed bluestone had been delivered to site. Hammond thought the ironstone made a good aggregate, but offered to tell Samson to use the bluestone if Monash preferred it. The abutments and centre piers were now finished, and Samson was preparing for the deck. Hammond pressed Monash to visit the town before the work was complete. It would restore peace and instil confidence, and the Councillors were keen to meet him.

Monash asked Samson to improve his daily site reports. "Your letters are very lengthy and contain a great deal of matter which is of no business or technical value, and it is difficult to pick out from them the material points on which information is really of value." Samson must have been downcast, because Monash's next letter told him not to take "passing comments and criticisms" personally. "A calm business attitude is essential, even under criticism." The fact that no-one from the Melbourne office had come to visit Samson was due to pressure of work in the Melbourne office, and not due to any lack of interest.

Early in June, P T Fairway did visit the site and found that the bridge deck had been built at the level originally called for, not two feet lower as had been agreed in the contract. This must have gone a long way to explain apparent overuse of concrete, which had been puzzling Monash. Hammond took full responsibility for the error, and even offered to pay with his own money for the extra concrete and earthworks. On 22 June, Samson reported that the concreting for the bridge had been completed, and he was now waiting for it to gain strength before stripping the formwork.

Problems develop

Early in July, Monash was concerned because a sample of concrete from one of the girders, sent to Melbourne, had not set properly after 14 days. It was porous and contained vegetable matter, and the gravel was loose. Monash hoped it was not a representative sample. He told Samson to check the girders themselves and decide on that basis when it would be safe to remove the props.

The girders must have appeared sound, because Monash soon urged Hammond to conduct the load test so that payment could be finalised. Unfortunately, other problems developed, and Hammond delayed. In August, floods caused scour at the ends of the wing walls, and a crack developed. Attempts to fix the problem with rock ballast bound with mortar were unsuccessful, and Hammond argued that the walls should be extended at RCMPC's expense. Monash pointed out that the drawings and specification had been approved by the Borough and the PWD. The firm's absolute guarantee could not be expected to cover such additional work, not foreseen prior to the recent floods. Further, he claimed that the problems had been aggravated by the high position of the deck, which was due to Hammond's error. Hammond disagreed, claiming that the wing walls were over-stressed, probably because RCMPC had used very wet earth as filling. He added: "I think all this would have been avoided if you had personally seen the site before starting work."

In mid-September, Monash sent P T Fairway to assess the situation, with full powers to decide on action. It was agreed that Hammond would have the stream re-aligned to reduce the potential for scour. In mid-October McDonald, the earthworks contractor, was given the task of lengthening the wing walls and adding to their height with red gum sheeting. McDonald found "softish shale" at the base of the walls, suggesting that Samson had not gone deep enough in preparing the foundations. (Samson should have obtained Hammond's approval of the quality of the exposed ground before he cast concrete on it, but the foreman claimed that Hammond was hard to find when needed for this purpose.)

It was also discovered that the concrete at the base of the piers had been eroded by floodwater and the reinforcing bars were exposed. Hammond suspected poor quality cement. Monash was in Sydney at this time, and his assistant engineers argued that the concrete must have been scoured before it had properly set.

It is also likely that the concrete had been insufficiently compacted. At the time, hand tampers were used to compact concrete, and it was difficult to do this in the confined space between the reinforcing cage and the formwork.

Remedial measures

Early in November, Monash sent foreman Patrick Geraghty to check the bridge. He confirmed that the concrete of the piers had been eroded to a depth of two inches (about 50mm), and there had been a great deal of scour. He underpinned the piers and abutments, excavating the soil beneath them and filling the space with concrete, so that the load was carried directly to firm rock.

Successful test

On 22 December 1909, Hammond informed Monash that the bridge had passed its test "splendidly" under a load of 37 tons. Correspondence between RCMPC, Hammond and McDonald over final settlement of accounts continued throughout 1910.