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Spillway Bridge, Upper Coliban Dam.
Three-span Monier arch bridge near Kyneton.

Photo 1996.   Coordinates: -37.28484, 144.397248

Introduction

The Upper Coliban Reservoir was created by the Victorian Department of Water Supply. The formation of the lake necessitated the diversion of a number of roads and the construction of several new bridges to carry them over waterways. Most of these bridges were to be the responsibility of the Shire of Kyneton which therefore had a say in decisions concerning cost and construction. However the Chief Engineer of the VWS, Stuart Murray, exerted considerable influence as the VWS was contributing much of the cost. After much local debate about alignment of the diverted routes it was decided to run the new Springhill-Kyneton Road over the the spillway below the dam. The bridge required at this location was thus on government land and entirely the responsibility of the VWS. (Two other bridges, Ross's and Manning's, would be covered by joint responsibilities.)

In January 1899 J. T. Noble Anderson wrote to Monash, who was then in Perth, "Stuart Murray tells me he will shortly be letting a reservoir at Upper Coliban …". Anderson felt this could provide an opportunity for application of the Monier system. [Sketch.] Following his return to Melbourne, Monash paid a quick visit to the Coliban area late in March 1900. His diary records that, working to a heavy schedule, he devoted two Sundays to the project; one at his own home and the other at Anderson's.

Attempts to secure contracts for the Council Bridges

From April 1900 Monash & Anderson were represented, in dealings with the Council, by a local engineer, W. T. Chaplin, who first introduced himself to them by letter as "a civil engineer &c in private practice in Kyneton". Chaplin was provided with photographs, drawings and specifications of typical bridges and a "text book" on the Monier system.

This might have been (a) the document prepared by W. J. Baltzer of the Sydney firm of Carter Gummow & Co. recording information obtained on his fact-finding mission to Europe, or (b) a copy of the thesis which Gummow submitted to the University of Melbourne in February 1900.

Chaplin suggested the partners contact the Shire Engineer, Mr J. Maxwell and, later, the VWS. The Minister for Public Works, Outtrim, with Murray, was at that time considering the location of the new roads. The Shire of Kyneton was a party to discussions under its President Henry Hill JP. Anderson and Monash already knew Murray well and it is doubtful whether they needed Chaplin's help and encouragement in approaching the VWS.

The engineering fraternity was tightly knit. Anderson had played a major role in collecting funds for a portrait of Murray which was presented to him, probably in December 1899, in recognition of his service to the community and to engineering. Anderson was Honorary Treasurer of the organising committee and seems to have written most of the letters asking for donations from fellow engineers. It is not clear from the records in the University of Melbourne Archives what spurred the occasion, other than the imminent departure for Europe of the "well-known artist Miss Josephine Muntz", sister of W J Muntz who was another close professional acquaintance of Monash & Anderson. Murray was still employed at the time, and under the terms of the Public Service Act it was necessary to obtain the permission of the Minister of Water Supply in order to make the gift.

On 2 July 1900 Anderson reported that he had seen J. G. Starr, the executive engineer at the VWS, and had quoted prices for arch bridges of various spans, ranging from 60 to 120 feet [18.3 to 36.6m], to use in estimating the costs of the various possible routes.

Developments were delayed by the illness and death of Maxwell, who was succeeded as Shire Engineer by Thomas Ewing. Chaplin cultivated Ewing, surveying sites with him and eventually taking him to Bendigo at Monash & Anderson's expense to see the arch bridges then under construction [Bendigo bridges]. Chaplin was convinced that after energetic lobbying he had persuaded the President and Councillors of the advantages of Monier arch bridges over conventional timber or iron structures, mainly because of their low maintenance costs and "indefinite" life. Anderson himself travelled to the area to meet Ewing and inspect bridge sites. On 5 March the "Kyneton Guardian" reported that the VWS had decided that one of the roads should cross the dam.

Despite Chaplin's efforts, Ewing maintained quite reasonably that arch bridges would be unsuitable for two of the Council crossings (Manning's and Ender's) because the surrounding country was flat. Costly approach embankments would be needed to slope the road up and over the crown of the arch. Nevertheless, Ewing agreed to allow the partnership to compete for the Council contracts. It was necessary in such cases for the Shire Engineer to prepare a design of his own to permit tenders by general contractors and to serve as a comparison against the cost of alternative designs such as Monash & Anderson's. Ewing's designs for single-span bridges consisted of stone or brick masonry abutments supporting steel joists and troughing. However he expected the partnership's Monier bridge to have ornamented spandrel walls like those at Anderson Street and a lavish parapet in stone or wrought iron. Chaplin pointed out that this would hardly constitute competition on equal terms and that in such a remote location ornament would be unnecessary. He suggested to Monash & Anderson that, to be on the safe side, they should submit two proposals, one ornamented and the other plain. The VWS engineers appear to have been initially luke-warm about Monier bridges. On 7 May 1901, in reference to the spillway bridge Starr noted "… as they [Monash & Anderson] have asked to be permitted to furnish a complete design and specification and tender, I think it will be wise to allow them to do so." [Internal VWS memo.]

On 14 May 1901 a major set-back occurred when the 29m arch of the King's Bridge in Bendigo, just completed by Monash & Anderson, collapsed under test. The bridge was highly skewed to the waterway, and following the evidence of Professor Kernot of the University of Melbourne, an inquest attributed the collapse to an excessive test load and the fact that currently accepted theory seriously underestimated the stresses in such an arch. However there were rumours of inferior construction practices and the editor of the "Kyneton Guardian", Mr Armstrong, published a leading article on 8 June 1901 which made reference to these while supporting the concept of Monier arches in principle. Chaplin told Monash & Anderson that the leading article was "inspired".

The source may have been the City Engineer of Bendigo, J. R. Richardson, who had strained relations with Monash & Anderson throughout the Bendigo contracts because of disputes concerning the inspection and direction of works in progress. However, this is purely speculation.

He wrote that the editor "is on the whole favourable to the Monier system … provided proper supervision is exercised … The position he takes up is that the abutment was improperly constructed of concrete containing a portion of pipeclay and failure was only to be expected." Chaplin suggests that Monash & Anderson write to the paper refuting these claims and that Murray be approached with regard to Ross's bridge and also the Departmental bridge over the byewash. On 3 June 1901 Chaplin continued "As you may suppose, the news of the failure of King's Bridge has created some concern here amongst those who looked forward to the adoption of Monier bridge for local requirements. It has given us a slight set back but this I believe will be only temporary." He reports that Ewing suspends judgement but thinks the failure would spoil "our" [Chaplin's and Monash & Anderson's] chances as far as Kyneton is concerned.

Chaplin sustained some hope, but on 28 June 1901 he reported that Murray had met the Shire Engineer and Councillors and had decided that the new Ross's Bridge would consist of rolled steel joists on stone piers, while Manning's Bridge would be of timber. The Councillors were disposed to accept Murray's decision. Ewing was open-minded but had stated "I can't say that I'm in love with the thing [the Monier arch] but am not averse to giving it a trial." Chaplin commented: "If we can successfully combat the prejudice against Monier bridges which has grown up in the minds of Councillors since the regrettable occurrence at Bendigo I think Mr Ewing will be inclined to be helpful." Chaplin noted that it would be the VWS which gained from the "reduction in first cost": the Council would benefit only from the saving in maintenance. This suggests that the stone-pier-and-steel-girder alternative was more expensive than the Monier arch.

Chaplin's lobbying of Ewing continued through September reinforced by news of the successful test of the Booth Street Bridge in Bendigo: the first to be tested after the collapse of King's Bridge. Ewing agreed to show Councillors a tracing of the design for the bywash bridge, but resisted Chaplin's attempts to obtain preferential access to Ewing's designs prior to the formal calling of tenders. It seems that all Chaplin's efforts in the locality were unsuccessful. He later complained that "local contractors are satisfied if they can only get wages out of a contract …"

Conception and Design of the Spillway Bridge

On 15 March 1901 a rough sketch was made showing the side elevation of the spillway bridge with a central clear span of 50 feet and two side spans of 30 feet (Dossier, p.48). The handwriting suggests it was made by Monash as a guide for his assistant J. S. Gregory who then prepared more careful versions. The first of these shows the same scheme with a heading "Coliban No.1 Design", later crossed out and changed to "Coliban No.2 Design" (Dossier, p.49). The second shows half of a side elevation of a bridge with three equal clear spans of about 40 feet. This was originally entitled "Coliban No.2 Design", later crossed out and changed to "Coliban No.1 Design" (Dossier, p.50). Assuming these alterations were contemporary, the change suggests that the version with unequal spans was at first preferred.

This may have been because it followed the precedent of the Fyansford Bridge. Also, it may have been thought to have more visual appeal than the equal-span alternative. However, unequal spans produce unequal thrusts on the intervening pier and, as at Fyansford, a thicker and more expensive pier is required. Furthermore, the unequal spans would have required two sets of centering, one 50 feet long and the other 30 feet. Equal spans permitted the re-use of one set 40 feet long.

An internal memorandum dating probably from 10 April 1901 summarises "Mr Starr's requirements" as for a single clear span of 126 feet (35.4m) with a roadway 18 feet wide (5.49m). Presumably in response to this, a pencil drawing was prepared on 15th showing a single arch with a rise of 19.5 ft (5.94m) [Dossier, p.51]. Calculations for quantities in the spandrels are attached, so it appears that the option was seriously considered. It should be noted that this was just before the collapse of King's Bridge, Bendigo [oblique span 28.5m] which occurred on 14 May 1901.

The first sheets of arithmetic calculations which we have are for the version with three equal spans, initialled by J. S. Gregory and dated 20/5/01. These are to compute the centre of gravity of one half of the span. The following day, calculations were made, entitled "Rough Calc. for curve", for an alternative design consisting of a bare Monier arch carrying timber trestles to support a timber deck. [When the Dossier was written it was first thought that these calculations were for the centering.]

Early in July 1901, Monash & Anderson prepared a draft specification for the spillway bridge and sent a proposal to Murray, quoting a price of £700. (It was standard practice throughout the period for Monash & Anderson to prepare the specification for approval by the client.) A copy of a memorandum from Starr shows that two proposals were made, one with solid spandrels, and the other with bare Monier arches carrying a timber superstructure.

In January 1899, at a desperate stage in the negotiations to obtain the contract for the Fyansford Bridge, J. T. N. Anderson made a similar proposal involving a skeletal steel superstructure resting on bare concrete arches. He noted that this could be replaced by spandrel walls and filling at some time in the future when finance became available. In February 1900 a proposal was made for a bridge of 100 ft span over the Goulburn River at Jamieson with a permanent timber superstructure consisting of a deck supported on trestles from a Monier arch.

The arches as designed were 7" thick at the springings and 5" at the crown. Anderson followed up the proposal with a visit to the Department in mid-July. Starr requested that he bring the drawings of the Anderson Street (Morell) Bridge, but as these had been returned to Carter and Gummow in Sydney, Anderson brought the drawings for the Fyansford bridge instead. It is obvious that Starr was concerned about the slenderness of the arch because the next day Anderson sent him a copy of the "text-book" mentioned above, noting European examples of much more slender arches.

These included Bauschinger's experimental arch in Vienna with a span of 32'-8" and a thickness of 5 ¾ inches, and the Wildegg Bridge of 171 feet span which was 6 ¾ inches thick at the crown. (The metric equivalents must have been about 10m, 145mm, 52m and 170mm respectively.)

Starr recommended to Murray that the alternative with timber superstructure could be dismissed "without examination in detail as the risk of the arches being injured by the vibration of the timber superstructure under heavy moving load is too great to be accepted." Regarding the version with full spandrels, he argued that although the theoretical stresses in the slender arch were well within the capabilities of the concrete, with "such a considerable part of the total load in motion … the vibration may before long endanger the cohesion of the material in the arch." He therefore recommended the thickness be increased to a uniform 10 inches and that the haunches be filled to a certain level with concrete. He noted that the spandrel walls were to be "secured with cross ties of iron" presumably against the bulging which had proved a problem at Wheeler's Bridge some months after its completion. Starr also recommended that the handrails be made heavier to avoid giving the bridge "a paltry appearance".

On 10 August 1901 Murray wrote to a superior officer, possibly the Secretary or Minister, recommending that the Monash & Anderson design be adopted. Its price was now £847-19-0. He noted that "Mr. Starr's estimate for a first class timber bridge, on piers of brick masonry, is £600" and pointed out that the lower maintenance costs: £2-l0-0 per annum for an indefinite life ("it will probably endure for some centuries") compared well with £12 per annum for a timber bridge whose timber parts would need replacement in about 60 years. Thus, he concluded, "the Masonry bridge is much the cheaper of the two". On 17 August 1901 the tender was accepted by the VWS.

A few days later, Gregory prepared final calculation sheets and graphical constructions of the thrust line. His drawing of the structure, first prepared on 6 August carries VWS amendments in red added on 19th and in green added on 26th (Dossier, p.53).

The "stress" diagrams would now be called "force" diagrams, although the stress in the cross-section at crown and abutments was calculated from the force at these points and entered on the drawing. The monogram is reproduced below. The calculations for the final design consisted of a single page of mainly tabular figuring and one drawing plotting the thrust line on the arch profile. For a glance at the drawing click here, then return to this Coliban History by scrolling down and clicking "Return link". For a glance at the tabulation click here, scroll down and click "Return link". For a full explanation of the tabulation and drawing (which assumes some knowledge of mechanics) click here. Further calculations and drawings are included in Appendix E of the Dossier.

Initials JM with the stroke of the J forming the first stroke of the M. Dated 27 August 1801.On 27 August a tracing of the Coliban "stress" diagram was made bearing the monogram "JM" in the bottom corner. A definitive drawing (known from a blueprint) was produced on 29 August (Dossier, p.54). Early in September 1901 Gregory prepared drawings for the centering (Dossier, p.55). "Stress" diagrams were prepared for the arch rib alone, just prior to concreting of the first arch on 3 May 1902, and again on the very day it was turned. These were presumably to ensure that the centering could be safely removed leaving the bare arch standing without propping.

Construction of the Spillway Bridge

When the contract was signed for the bywash bridge on 22 October 1901, the VWS was keen to have an early start because of the delay which had occurred owing to Maxwell's death and the long debate on alternative routes. However, it was necessary to await completion of the spillway before the bridge could be built. It was not until 28th January 1902 that Noble Anderson's brother Jack arrived in Kyneton to act as foreman. He rented a room with the local barber to serve as bedroom and office, and made contact with the general contractor and with Starr, who happened to be up from Melbourne. For a while he was "at a severe disadvantage" because his bicycle had not yet arrived from Bendigo. He set about ordering bricks to be delivered and looking for sources of good quality sand and gravel and for spalls [large stones]. This was not easy and the best gravel he found was at the Golden Gate gold mine near Malmsbury (also described as near Taradale) which would have to be carted nine miles. Bullock drivers and teamsters were found to cart cement and bricks from the railhead at Redesdale Junction at 3/- and 4/- per ton respectively. Road "metal" and spalls were to come from the quarries of Davies & Flight who were constructing the reservoir. The supply of bricks presented some problems. Most were ordered from B. H. Beer's Kyneton Brick and Tile Works at Tylden, but for the facing of the spandrels and abutments they were transported from Northcote in the hope of obtaining better quality.

Difficulties were also experienced in finding skilled and unskilled labour. At times it was necessary to borrow men from the general contractor. Prior to the turning of the third arch, Jack Anderson reported "… on Saturday we will be unable to hire men as the football season is now on & all the young men about here are players …" Another distraction was "the fuss about the coronation". The labourers objected to the hardness of the bluestone which was to be broken by hand for road metal and Anderson was obliged to increase payment from 2/6 to 3/- per cubic yard on the understanding that a uniform gauge of 2 inches would be achieved. Tradesmen he had organised locally often failed to turn up, and as the Melbourne tradesmen had plenty of work it was difficult to lure them out to the site. In April 1902 the bullock driver left the area, removing a source of cheap transport. Problems also arose because Davies & Flight were reluctant to give Monash & Anderson access to the incomplete spillway as their presence would interfere with the contractors' own work. After much temporizing on the part of Starr, who appears to have been unwilling to offend the general contractors, he was finally persuaded to set out the line of the bridge with Anderson, drawing an immediate protest from Flight. Fortunately Murray happened to be in the area and secured an agreement that work could start on one abutment as long as it did not directly interfere with Flight's operations. Disputes on this question continued into June.

Nevertheless the task of removing portions of the bluestone lining of the spillway, excavating foundations for the piers and abutments, and concreting these to the level of the arch springings proceded steadily with a minimum of labour. The brick facing of the piers was used as 'permanent shuttering'. The task of casting the Monier arches was to be done by a special gang of five men led by an experienced foreman Chris Christensen, all brought over from Bendigo. (It was considered essential to 'turn' an arch in a single operation: concreting it from one end to the other without stopping for more than an hour, so as to avoid 'cold' joints within its length.) Jack Anderson noted that Christensen would have to bring a bricklayer with him "as the haunch filling is to go in while the arch is being turned and it is brick faced on each side." On 28th and 29th April 1902, Monash visited the site with Starr. He returned on 1 May to help prepare for the 'turning' of the first arch which occurred on Saturday 3 May. Jack Anderson wrote "Mr Monash and C. Christensen were present all day and directed operations. The largest number of men employed at any one time was 18. The arch is setting well and no sign of any movement can be detected anywhere."

Subsequent reports indicate considerable concern for the safety of the arches, and a careful watch for signs of deformation and distress, probably inspired by the collapse of King's Bridge, Bendigo, the previous year. On 7 May, Jack Anderson reported that he was watering the arch and could detect no movement "such as Mr Monash pointed out might possibly occur". It was setting "most satisfactorily". On 9 May he wrote that he could detect "no movement nor as yet any shrinking away of the laggings from the compo at any point" and on 19th that "Arch No.1 now looks so well that I feel confident that the centres can be struck at any time without any risk." This took place the following day and Anderson reports "… during this operation I carefully watched for any possible deformation but none occurred … the compo even where covered by the lagging has set remarkably well".

The 'laggings' were the narrow planks used to form the curved surface on which the arch was cast.
It was erroneously believed that setting depended on drying.

On 27 May, Monash was again present for the turning of the second arch. Jack Anderson reported on 11 June "… I had intended striking the centres today but on further examination decided to wait a couple of days longer as owing to the cold and wet weather this arch has decidedly not come on so quickly as No.1. This morning it was still possible to work the point of a knife ½" into the compo with little exertion." On 16 June he sent a telegram, lodged at 1.47 pm, saying "Coming down to see you today reach office 4.30." Monash's diary for that day contains the entry: "Scare re Coliban 2nd Arch". On 18th Anderson wrote that he and a labourer had "… proceeded to ease the wedges under centres in the order mentioned by Mr Monash. This we did gradually carefully watching the arch and haunch filling and continued as we could detect no movement till the laggings had fallen ½" from the arch all over." They left the centering in this condition while they ate dinner, after which they could still detect no movement. The width of a crack observed in the left hand haunch filling had not increased. Anderson continues: "… although I have since examined the under surface of the arch at intervals I can detect no flow of any sort and am satisfied that the crack is confined to the haunch filling alone."

Presumably to cope with the scarcity of labour, it was decided to turn the third arch in two parallel strips, each half the width of the bridge. The first strip of Arch No.3 was safely turned on 27 June 1902 with fourteen men employed. The second strip was scheduled for completion the following day. Jack Anderson reported that owing to the high rise and appreciable skew, the placing of the 'side boards' which confined the concrete had been difficult and the rings of the arches were not in perfect alignment. He proposed to cover the difference with an ample coat of plaster (mortar). On 7 June the centres of the third arch were safely struck. On 20 June 1902 Jack Anderson reported that he had paid off the last labourer, and that as the general contractor had started working on the road, he assumed they had effectively taken over the bridge from Monash & Anderson.

The strange question of the skew on the bridge.

Severe problems were caused in the early stages of the contract by confusion over the exact location and alignment of the bridge. Noble Anderson claimed that in August 1901, Starr vaguely indicated an alignment which would involve considerable skew, and that when Anderson suggested a more direct alignment, Starr protested that he would then not get the full 126 feet promised in the contract documents. Anderson pointed out that as it was a schedule of rates contract this would not matter. The Monash & Anderson drawing of 6 August 1901 shows the bridge square to the spillway walls, but the blueprint of 28 September 1901 significantly omits the line of the walls. According to Jack Anderson, Starr repeated his statement on 11 February 1902, saying "it will be necessary to skew the bridge to accommodate its length to the width of the Bye wash …" The topography of the site suggests no other obvious reason for building the bridge on the skew. For about a fortnight in February 1902, Starr delayed the setting out, claiming he was not in possession of the drawings. When this matter was resolved, he claimed there was no point in setting out the bridge until the general contractors had finished work in the byewash. (At this stage they would have been lining the bottom of the spillway with rectangular bluestone blocks or 'pitchers'.)

As noted above he was finally persuaded to do so on 24th in the company of Anderson, insisting on a skew of about 20 degrees. On 5 April the partnership submitted a claim to the VWS for the extra cost incurred in adapting their 'plant' to the skew. This presumably meant adapting the centres and formwork. The centres used were transported from Bendigo and it is possible that the components came from the High Street Bridge or the second King's Bridge.

The second King's Bridge was tested on 28 January 1902. A note from Jack Anderson to Christensen says the latter has forgotten to send the bolts necessary for assembling the centering and JA remembers them being in a bag under a bench in the hut at High Street [Bridge, Bendigo].

This was even more skewed (50 degrees) and its spans were 13.2m compared with the 12.0m for Coliban, but the centres could have been cut shorter to suit Coliban. The geometry of the centring was further complicated by the fact that the walls of the spillway converge at this location, so that one side of each arch is 11.71m in length while the other is 11.86m. Jack Anderson, in a letter to his brother, wrote "… this arch has been and is on my mind. I consider it the most awkward arch we have ever tackled'. A document dated 17 July 1902 shows that Monash & Anderson were prepared to take the disputed claim to arbitration, though there is no record of this having occurred.

Note 1: The history above was extracted from our Dossier and edited for presentation here. The Dossier includes details of archival sources, dimensions, a list of personalities, and a "Timeline" in which all relevant correspondence known to our research team was recorded chronologically in precis or verbatim form.

Note 2; Important correction. Due to a mental aberration I quoted J.T.N. Anderson's full name wrongly on page 19 of the Dossier. It is Joshua Thomas Noble Anderson.