Gunns Forest Products Ltd v Fulghum Industries Inc
[2007] TASSC 20
•20 February 2007
[2007] TASSC 20
CITATION: Gunns Forest Products Ltd v Fulghum Industries Inc [2007] TASSC 20
PARTIES: GUNNS FOREST PRODUCTS LTD
v
FULGHUM INDUSTRIES INC and
GRAYSON ENGINEERING LTD
TITLE OF COURT: SUPREME COURT OF TASMANIA
JURISDICTION: ORIGINAL
FILE NO/S: TRA 490/2002
DELIVERED ON: 16 April 2007
DELIVERED AT: Hobart
HEARING DATE: 21 – 24, 27 – 30 November 2006
JUDGMENT OF: Blow J
CATCHWORDS:
Evidence – Burden of proof, presumptions, and weight and sufficiency of evidence – Proof of particular matters and relationships – Other particular matters – Cause of collapse of crane.
Aust Dig Evidence [170]
REPRESENTATION:
Counsel:
Plaintiff: K E Read
First Defendant: M E O'Farrell
Second Defendant: N Sweeney
Solicitors:
Plaintiff: Ogilvie Jennings
First Defendant: Dobson Mitchell & Allport
Second Defendant: Page Seager
Judgment Number: [2007] TASSC 20
Number of paragraphs: 76
Serial No 20/2007
File No TRA 490/2002
GUNNS FOREST PRODUCTS LTD v
FULGHUM INDUSTRIES INC and
GRAYSON ENGINEERING LTD
REASONS FOR JUDGMENT BLOW J
16 April 2007
This is an action for damages in relation to the collapse of a crane at the plaintiff's woodchip mill at Hampshire on 6 June 1998. The crane is one of two cranes at the Hampshire mill that were designed, supplied, installed, constructed, commissioned and performance tested by the first defendant ("Fulghum") pursuant to a contract with the plaintiff. Both cranes had been in use at Hampshire since March 1995. Fulghum is an American corporation, and was at all material times experienced in the design and construction of woodchip mills, including their cranes. The second defendant ("Grayson") undertook fabrication of the two cranes in New Zealand. The plaintiff contends that the collapse of the crane was caused by the negligence of Grayson in relation to the fabrication of some of its components. It also contends that the collapse was caused by breaches of the contract by Fulghum, especially on the basis that Fulghum supplied the crane with components that were not in accordance with its own designs.
Both defendants deny liability. Both contend that the collapse of the crane was caused or contributed to by the negligence of the plaintiff. The quantum of the plaintiff's claims is not disputed. Claims between the defendants for contribution were settled during the trial. The substantial question to be decided is what caused the collapse of the crane.
The crane
The two cranes are known as the north crane and the south crane. The one that collapsed was the south crane. I will describe that crane. The north crane was of identical design.
The purpose of the crane is to move logs. Logs are unloaded by it from trucks, either into a stockpile or directly into the plaintiff's mill. The crane is also used to move logs from the stockpile into the mill. The crane is mounted on a circular rail. The circle is a little over 20 metres in diameter. At the centre of the circle there is a concrete plinth or pedestal. The "tail" of the crane is mounted on that pedestal. The main truss extends from the pedestal to a position above the circular rail, where it is mounted on an A-frame. From the top of the A-frame, a jib extends out beyond the circle. A grapple is suspended from the jib. Logs are lifted and lowered using that grapple. The grapple is suspended from a travelling carriage on the jib, so that it can be moved towards the circle or away from the circle. The A-frame is mounted on the rail on wheels. At each of the two feet of the A-frame, there is a bogie with two wheels. Each of the wheels has flanges on either side of the rail. The crane is designed to travel on those wheels around the full 360 degrees of the circle, revolving around the central pivot, ie the central pedestal. It is designed to revolve in a horizontal plane. The crane structure is not designed to be raised or lowered. Only the suspended grapple is raised or lowered.
The crane collapsed as a result of the failure of a component in the central pivot assembly. A sketch of the central pivot assembly is attached to these reasons. The component that failed was the flanged base spool piece (item 13 on the sketch). Subsequent inspection revealed that a crack had been developing in it. The crane is designed to lift loads of up to 15 tonnes. The collapse occurred upon a load of about 14.7 tonnes being lifted. The flanged base spool piece is circular. Upon the load being lifted, the crack grew to complete a full circle, whereupon the crane became detached from the central pedestal and fell in a clockwise and outwards direction into the log stockpile.
The flanged base spool piece is the lowest metal component of the central pivot assembly. In layman's terms, it is a metal spool, on its side, attached to the concrete plinth by anchor bolts. There is a layer of grout between it and the concrete. It does not rotate. Above it, there is a bearing. The inner part of the bearing, which does not rotate, is bolted to the upper flange of the flanged base spool piece. The outer part of the bearing does rotate. Above the bearing there is a metal ring known as the bearing support ring (item 4 on the attached sketch). It is bolted, from below, onto the outer bearing race. Another component, referred to at the trial as "the barrel", but shown on the attached sketch as the pivot base plate (item 1 on the sketch), sits over the bearing support ring. Those two components are not bolted together or rigidly attached to one another. The design allows the barrel to tilt very slightly, while the bearing support ring is designed to remain horizontal at all times. For example, the barrel might tilt very slightly when a load of logs is picked up by the grapple, or when a load of logs is released from the grapple.
Around the circumference of the bearing support ring, there is a taller cylindrical ring (item 2 on the attached sketch) that is welded to the bottom of the pivot base plate so as to form part of the "barrel". Below that cylindrical ring, and under the outer part of the bearing support ring, there is a flat retaining ring which is attached to the outer bearing race. Above and below the bearing support ring there are neoprene rings (items 3 and 5 on the sketch). Neoprene is a somewhat flexible material that can be compressed and then return to its original shape. The upper neoprene ring is positioned above the bearing support ring and below the barrel. The lower neoprene ring is positioned below the bearing support ring and above the retaining ring that is attached to the outer bearing race. In layman's terms, the neoprene rings are designed to provide cushioning when the barrel tilts.
When the crane revolves, the components that revolve with it include the barrel (including the cylindrical ring that is welded to it), the bearing support ring, the two neoprene rings, the retaining ring, and the outer bearing race. None of those components is designed to revolve independently of any of the others. The design provides for very slight tilting, as I have described, and for the crane to revolve through 360 degrees, but no other movement within the central pivot assembly is provided for.
I have mentioned the anchor bolts by which the flanged base spool piece is attached to the central concrete plinth or pedestal. On 10 February 1998, three of those anchor bolts broke. The plaintiff's staff reported those breakages to Fulghum. Fulghum's staff advised them to repair the broken bolts by using hexagonal fittings and a non-shrink grout. Repairs were carried out in accordance with that advice, and the plaintiff continued to use the crane, apparently without incident, until its collapse on 6 June 1998.
The plaintiff contends that the crane collapsed because the bearing support ring and the barrel were not manufactured and assembled in accordance with Fulghum's design. One of Fulghum's design drawings required the barrel to be circular, and to have an internal diameter of 1118mm, plus or minus 1mm. Another drawing required the bearing support ring to be circular, and to have a diameter of 1111mm, plus or minus 0.1mm, and that its outer vertical surface be machined. If those parts had been manufactured as designed, there would have been a clearance of 3.5mm around the whole circumference of the bearing support ring.
The outer vertical surface of the bearing support ring was not machined. Ordinarily, it would have been flame cut first, and then machined. Contrary to normal practice, it was flame cut, but not later machined. The crane was assembled with it in that condition. Once it was assembled, the circumference of the bearing support ring was wholly within the barrel, and could not be seen. Fulghum's personnel in New Zealand apparently did not observe the bearing support ring prior to its installation, and consequent disappearance, inside the barrel.
After the collapse of the crane, an investigation was carried out on behalf of the plaintiff. It was discovered that the bearing support ring had not been machined. Measurements were taken of the diameters of the bearing support ring and the barrel. Neither was a perfect circle. Neither was within the tolerances specified by Fulghum (plus or minus 0.1mm and 1mm respectively). The diameter of each was measured at 45 degree intervals. The measurements of the internal diameter of the barrel, in clockwise order when viewed from above, were 1114mm, 1116mm, 1118mm, and 1114mm. The measurements of the external diameter of the bearing support ring, in clockwise order when viewed from above, were 1111mm, 1113mm, 1116mm, and 1114mm. No record was made as to the orientation of the ring in relation to the barrel. It would have been possible, on assembly, for the bearing support ring to have been orientated so that it fitted within the barrel. It may or may not have been possible for it to have been orientated so that there was some clearance between it and the barrel around the whole of its circumference. But it would not have been possible for it to have been orientated so that, around the whole of its circumference, there was a clearance between it and the barrel of the order of 3.5mm as required by Fulghum's design.
The plaintiff contends that the bearing support ring and the barrel must have been jammed together at least since operations commenced at the mill; that the barrel was therefore not able to tilt or move in relation to the bearing support ring at all; that excessive forces were therefore transmitted to the flanged base spool piece from the time operations commenced; and that those forces caused it to start cracking, caused its failure, and caused the collapse of the crane.
The defendants contend that the crane collapsed because the plaintiff did not properly maintain the circular rail. They contend that excessive forces were transmitted to the flanged base spool piece as a result of the rail being too low; as a result of it not being level, and varying too much in elevation; as a result of excessive vertical movement, or "pumping", under loads; and as a result of it not being of a consistent radius, with parts of the rail being too close to the centre of the circle and other parts being too far from it. They contend that the plaintiff has not established on the balance of probabilities that the collapse of the crane resulted from any fault or defect in the fabrication or assembly of parts of the crane.
The evidence
The parties tendered models, photos and other documentary evidence. Five witnesses gave oral evidence. All had substantial experience in engineering. Three of them – Mr Wakeman, Mr Stanford, and Mr Gilbert – were called by the plaintiff. Mr Wakeman is a mechanical engineer who was providing services for the plaintiff at the time of the crane's collapse. He investigated the possible causes of the collapse and supervised its re-erection. Mr Stanford is a mechanical structural engineer who was employed by the plaintiff from 1995 to 2000, and was responsible for engineering matters at sites including its Hampshire woodchip mill. Mr Gilbert is an independent mechanical engineer who was engaged by the plaintiff's solicitors as an expert witness. Fulghum called one of its vice-presidents, Mr Lewis. Grayson called a Mr Daly, who had been employed by it as a project manger, and had been responsible for the overseeing of the fabrication of the parts of the crane during the latter half, or thereabouts, of that project. Whilst all of these witnesses had substantial practical experience in engineering, none of them had impressive academic qualifications. All parties were somewhat handicapped by the unavailability of evidence. After the collapse of the crane, it was re-erected, and the barrel was re-used. The barrel was therefore not able to be inspected, measured or photographed after the re-erection. The neoprene rings were not re-used, but they had become unavailable. Mr Wakeman thought that they looked like rubbish, and that someone must have assumed that they were rubbish and thrown them away.
The plaintiff contends that the available circumstantial evidence establishes that there can only have been one possible cause for the collapse of the crane, namely the jamming of the bearing support ring inside the barrel, at or before the installation of the crane at Hampshire, as a result of the negligent fabrication and assembly of components in the pivot mechanism by the defendants. It contends that there is evidence that rules out all other possible explanations for the collapse of such a crane, including poor rail maintenance.
Did poor rail maintenance cause the collapse?
One of Fulghum's design drawings required the radius of the rail circle, measured from the centre of the pivot to the centre of the rail, to be 20280mm. The same drawing specified the elevation of the top of the concrete pivot foundation pedestal, and showed the top of the rail was to have a relative elevation of –0.337 metres. That is to say, the drawing required the top of the rail to be level, and to be 0.337 metres lower than the top of the concrete pedestal.
Fulghum provided the plaintiff with a manual relating to the crane. Maintenance requirements were specified on page 9 of the manual. The following appeared on that page:
"track limits:
Elevation ± 1 inch
Diameter ± ½ inch
After startup, check track elevation and diameter. Check monthly for three months, and every six months thereafter."
The tolerances that were thus specified in relation to the rail were relaxed by Fulghum on 4 March 1997. On that day, Fulghum sent the plaintiff a fax containing new maintenance specifications. That fax included a drawing which specified that the radius, from the centre of the pivot to the centre of the rail, was to be 66 ft 6 7/16 ins ± 3/8 inch. That equates to 20280.3mm ± 9.5mm. It should be noted that the tolerance specified on this occasion related to the radius, whereas the tolerance ± ½ inch originally specified in the manual related to the diameter. The faxed drawing specified that the difference in levels between the top of the rail and the top of the lower flange of the barrel – not the top of the concrete pedestal – was to be 2 ft 7½ ins ± 1½ ins. The tolerance of ± 1½ ins equates to ± 38.1mm.
Significant forces can be transmitted to the pivot if differences in rail elevation result in one bogie being significantly higher than the other, but nothing was specified by Fulghum in the manual or any other document before me as to tolerances relating to the gradient of the rail, or the relative elevations of the two bogies. There was also evidence from Mr Lewis that significant forces can be transmitted to the pivot as a result of the rail "pumping" – ie moving up and down when loads of logs are released or lifted by the grapple – but no tolerances were specified in the manual or any other exhibit in relation to such vertical movements.
Fulghum was not responsible for the installation of the rail. The plaintiff arranged for it to be installed prior to the installation of the crane. The rail is installed on a compacted earth mound. It is mounted on ordinary timber railway sleepers which are set in ordinary blue metal railway ballast on top of the mound. A survey of the completed rail installation was undertaken on 11 October 1994, prior to Fulghum commencing the installation of the crane. The elevation of the rail and its distance from the centre of the pivot pedestal were measured and found to be within the design tolerances. The elevation of the rail varied from 6mm below design level to 2mm above design level. The radius varied from 8mm less than the design figure of 20280mm to 6mm greater than that figure.
Substantial downwards forces are exerted on the rail through the bogie wheels whenever the crane takes up a load of logs. Mr Stanford estimated that, at least when he worked at Hampshire, the crane was handling about one million tonnes of logs per year, involving about 80,000 grapple-loads of about 12.5 tonnes each being taken from arriving trucks. Since arriving trucks are required to stop for unloading at a particular location outside the circle, the impact of the forces from the picking up of logs from trucks is not spread uniformly around the circle. Forces which would tend to cause the rail to subside are repeatedly exerted near the truck unloading area.
The exhibits include documents recording rail elevation levels measured on four later occasions. One is undated. The others are dated 14 February 1997, 19 December 1997, and 11 June 1998. The measurements taken in June 1998 were recorded by a surveyor, Mr Plunkett, a few days after the collapse of the crane.
Mr Plunkett's survey suggests that the rail was slightly below the level required by Fulghum's design. Its highest and lowest points were respectively 24mm and 69mm below what he took to be the required level. Both Mr Wakeman and Mr Lewis took the view that Mr Plunkett's figures needed to be adjusted. Mr Wakeman reduced Mr Plunkett's figures for the distances of the rail below design level by 19mm, so that, on his figures, its highest and lowest points were respectively 5mm and 50mm below design level. Mr Lewis made an adjustment of 15mm, so that his corresponding figures were 9mm and 54mm respectively. If his figures are correct, the rail was out of tolerance, ie more than 38.1mm below design level, at only 5 of the 17 points at which Mr Plunkett measured its elevation. It seems that the variations in figures may have had something to do with the fact that, in accordance with Fulghum's fax of 4 March 1997, the required elevation of the rail was to be calculated by reference to the top of the lower flange of the barrel – something that was no longer in position after the crane collapsed.
The undated document indicates that, on a date unknown, there was a variation in elevation of 23mm between the highest and lowest of 11 points around the track. On 14 February 1997 elevations were measured at 19 points by reference to an arbitrary datum, revealing a difference of 35mm between the highest and lowest of those points. On 19 December 1997, elevations measured at 23 points by reference to an arbitrary datum revealed a variation of 42mm between the highest and lowest of those points. There is no evidence as to how the elevation of the track on those three days compared to the elevation specified in Fulghum's design. Perhaps the people who took the measurements were only interested in the consistency or otherwise of the level of the track, and not in its elevation by reference to any particular datum point. All three of those surveys indicated that the variations in the elevation of the rail were within the tolerance of plus or minus 1 inch (ie plus or minus 25.4mm) specified in Fulghum's fax of 4 March 1997.
Mr Stanford gave evidence that temperatures at Hampshire vary between – 8°C and 35°C with the result that the rail expands and contracts, causing a variation in its circumference of up to 25mm. Dividing that figure by 2π, this equates to a variation of about 4mm in its radius. However, Mr Stanford said that the rail tended to remain in place at one point "and the other side grows". In that situation, the distance between the centre of the pivot and the point diametrically opposite to the fixed point would vary with expansion and contraction by as much as 8mm. That variation, on its own, is within both the original and revised tolerances specified by Fulghum.
On 11 June 1998 Mr Plunkett measured the radius of the rail circle at 17 points around its circumference. The radius varied from 20262mm (18mm less than the design figure) and 20298mm (18mm above the design figure). On the basis that the fax of 4 March 1997 allowed for a tolerance of 9.5mm, the two extreme points were outside that tolerance by some 8.5mm. Of the 17 radius measurements taken by Mr Plunkett, six were more than 9.5mm above or below the design measurement of 20280mm.
Apart from the initial survey measurements of 11 October 1994, Mr Plunkett's measurements, and Mr Stanford's oral evidence, I have no other evidence as to measured variations in the radius of the rail circle up to the time of the collapse of the crane. It would seem that, apart from the elevation and radius measurements that I have referred to, no other measurements were made. The maintenance report prepared by the plaintiff's mill manager, Mr Dazeley, in or about April 1999 was tendered as an exhibit. He wrote the following in that report as to the elevation and diameter of the rail track:
"First checked on 7/8/1996. Checked 4 times between then and the end of 1998. Last checked on 20/3/1999. Records of levels maintained by C Mann. No records maintained at the Mill. No measurements taken of rail diameter. New measurement system implemented, with first check done on 20/3/1999. No records. Refettled on 11/12/1997 and again on 20/3/99."
If the radius of the rail were a little greater than that specified by Fulghum, the outer flange of the wheels would scrape against the outer side of the rail, leaving a wear pattern on the outer side of the rail, and perhaps leaving metal filings beyond the rail. If the radius were a little less than that specified, there would be similar wear patterns on the inner side of the rail, and perhaps filings beside the rail on the inner side. Representatives of Fulghum visited the site on 4 November 1998, about five months after the collapse. One of them reported as follows:
"Looking at the rail we could see that the crane wheels had been rubbing on the inside of the rail in a number of different places and the wear on the top of the rail appeared to wander from one side to another in places."
There was evidence that the bogies could be adjusted to some extent to allow for changes in the radius of the rail circle. That is to say, the wheels could be moved towards the centre of the circle, or away from it. Mr Stanford mentioned difficulties in aligning the bogies with the rail, but otherwise there was no evidence of any such adjustments ever having been made.
In the days following the collapse of the crane, Mr Wakeman investigated the possibility of "pumping" causing or contributing to the collapse of the crane by measuring the extent of "pumping" when the surviving north crane took up a grapple load of logs. The rail deflected downwards a maximum of 14mm when the grapple was loaded.
The crane was designed to withstand the forces that would ordinarily be generated as a result of (a) the rail being a little too high or a little too low; (b) variations in rail level, which would result in one bogie being a little higher than the other; (c) "pumping" or vertical movement of the rail upon a load of logs being lifted or released; (d) small variations in the radius of the rail circle; and (e) forces generated by the movement of the loaded grapple towards or away from the centre of the circle. Some of these factors would cause the barrel to tilt slightly in relation to the bearing support ring, if it were free to do so. The neoprene rings were designed to be compressed when there were such movements, so that the forces upon the anchor bolts and the pivot base would be substantially reduced. Other movements, particularly those resulting from minor variations in the rail circle radius, would result in horizontal forces. The provisions in the design for a clearance of the order of 3.5mm around the circumference of the bearing support ring, and for clearances between the rail and the inner and outer wheel flanges, made allowance for those horizontal forces.
The plaintiff contends that at all times and in all respects the rail was either within tolerance or only slightly out of tolerance, and that the forces generated as a result of such irregularities could all have been absorbed by the neoprene rings if the bearing support ring had not been jammed. The upper neoprene ring was originally 25mm thick. Mr Wakeman performed some calculations as to the effect that a drop in rail level would have in relation to the compression of that ring. He calculated that it would be compressed by 2mm if the rail were 73.8mm below design level. Mr Lewis calculated that if the rail level were 38mm below design level, that would result in the upper neoprene ring being compressed by 1.04mm. Mr Wakeman also calculated that a "pumping" deflection in the rail of 14mm, as measured for the north crane, represented only a 0.4mm compression of the upper neoprene ring. As to the variations in the radius of the rail circle, Mr Wakeman said the following in a report dated 2 July 1998:
"The maximum rail eccentricity is 18mm which can be accommodated within the wheel track width between the flanges. The rail eccentricity is not seen as a contributing factor to the failure."
That assertion was not contradicted by any evidence as to the clearances allowed for in the design between the rail and the flanges. Further, there was evidence that horizontal forces resulting from rail eccentricity could to some extent be absorbed as a result of the crane structure having some flexibility.
In 1999, Fulghum sought expert advice about the crane from Professor Lawrence F Kahn of the Georgia Institute of Technology in Atlanta. He calculated the maximum allowable stress cycle for the anchor bolts of the pivot mechanism to be 9ksi. Making an assumption that the upper neoprene ring was not working, and that the barrel was not free to pitch and roll in relation to the bearing support ring, he calculated that a vertical settlement of the rail displacing both wheels 2.5 inches downwards would be needed to cause a maximum tensile stress in the bolts of 9ksi. In other words, he thought the rail would need to be 63.5mm below design level before excessive stresses resulted as a result of that cause alone. When asked to assume that the neoprene ring was working, ie that the bearing support ring was not jammed, he said that "the neoprene bearing pad would permit sufficient relative vertical displacements such that almost no weld stresses would be created by the relative settlement of the bogies".
Dr Kahn also expressed the view that the stresses created as a result of the two wheels of a bogie being at different elevations as they moved around the track would be considerably greater than those resulting from the track being below design level. That proposition was not disputed at the trial. However Dr Kahn considered that excessive stresses would occur only if the neoprene ring were not functioning.
It is of course necessary to consider the cumulative effect of the forces generated as a result of all irregularities relating to the rail. Mr Stanford gave evidence of a simple experiment that he performed compressing hard neoprene with an original thickness of 25mm using a vice. He was able to compress it to a thickness of 20mm using very little force, and was ultimately able to compress it to a thickness of 5mm. On the basis of that evidence, Dr Kahn's reports, and the evidence of Mr Wakeman and Mr Lewis as to the effect on the upper neoprene ring of the rail being low, I am reasonably satisfied that the forces generated as a result of the rail being as much as 54mm below design level, the rail varying in elevation and radius as noted by Mr Plunkett, and "pumping" displacements of the order of 14mm would have been well within the capacity of the neoprene ring. If the barrel was free to tilt in relation to the bearing support ring, and the upper neoprene ring was functioning, much greater variations from Fulghum's design, in relation to the rail level and/or radius, would have been needed to exert excessive forces.
Mr Stanford gave evidence about rail maintenance that suggested that a lot of attention was paid by him to the need to maintain the level and radius of the rail. Mr Wakeman gave evidence that a lot of work was done in relation to rail maintenance, particularly a lot of fettling. I accept their evidence as to rail maintenance, and infer from it that the measurements in evidence as to the rail levels and radii fairly represent the state of the rail during the years the crane operated before its collapse. There was evidence that the south crane was used about three times as much as the north crane. Had the rail not been maintained, one would have expected significantly greater "pumping" in the case of the south crane than that measured by Mr Wakeman in relation to the north crane. However I infer, because of the evidence of attention to rail maintenance that I have mentioned, that the "pumping" in relation to the south crane was not significantly worse than that relating to the north crane.
There was some evidence as to the conduct of Fulghum's experts that counsel for the plaintiff relied upon as tending to suggest that the state of the rail was not as worrying as Fulghum is now suggesting. After the three anchor bolts failed in February 1998, although Fulghum made recommendations as to repairs, it made no recommendations as to the inspection and maintenance of the rail. Following the collapse and re-erection of the crane, it was re-commissioned on 10 July 1998. Although Fulghum representatives inspected the site on 4 November 1998, no recommendation was made at that stage in relation to rail maintenance. However on 12 February 1999 Mr Lewis sent the plaintiff a "cease and desist notice" insisting that it stop using both its cranes until both of their rail systems were brought within Fulghum's specified operational tolerances. That notice seems to have been ignored, without any untoward results. Mr Lewis and Fulghum's other personnel have very substantial experience in relation to the operation and maintenance of cranes like those of the plaintiff. If, as Fulghum now contends, strict compliance with its specifications as to the elevation and radius of the rail circle was essential to the safety and survival of the crane, I think they would have urged the plaintiff to carry out rail maintenance much earlier than 12 February 1999.
I am satisfied that the forces exerted upon the central pivot generated as a result of the rail being below design level, it being uneven in level, "pumping", and the eccentricity of the rail circle were all capable of being absorbed by the neoprene rings if the central pivot mechanism had been intact. If, as the defendants assert, the bearing support ring was not jammed inside the barrel, those forces could not have caused the collapse of the crane. I therefore reject the defendants' contention that the crane collapsed because of poor rail maintenance. The ruling out of poor rail maintenance as a possible cause of the collapse of the crane is an important step towards acceptance of the plaintiff's circumstantial case.
Miscellaneous rejected hypotheses as to the cause of the crane's collapse
Mr Wakeman investigated a number of hypotheses as to the cause of the collapse of the crane in 1998.
The load of logs that was being lifted when the crane collapsed remained intact. The load was subsequently taken away and weighed. It weighed 14,700Kg. According to Fulghum's specifications, the safe working load for the crane was 15,000Kg. There is no suggestion that the specified safe working load was inappropriate.
The investigations of Mr Plunkett, the surveyor, revealed that the base spool piece had been installed level on its foundation.
The broken base spool piece was inspected and tested by a metallurgist. That testing established that the base spool piece was not defective, and that it had failed as a result of excessive stresses over a period of time. These had initially resulted in cracking that extended around about 320 degrees of the base spool piece. The final fracture involved the crack extending from 320 degrees to the complete 360 degrees.
Mr Wakeman also investigated, and ruled out, the possibility that the base plate at the tail of the crane structure was not square in all planes to the centre line of the structure.
The barrel and the bearing support ring
Having regard to the measurements of the internal diameter of the barrel and the external diameter of the bearing support ring, it was no doubt possible for that ring to have jammed within the barrel. It is worth noting that, if the ring were tilted in relation to the barrel, that would increase the chance of it jamming. If the ring had been fabricated as designed, it would have been 1111mm in diameter and 65mm thick. Using Pythagoras' theorem, I have calculated that the distance from a point at the top of the circumference of a ring of those dimensions to the diametrically opposite point on the bottom of the circumference would be about 1112.9mm. That is to say, the tilting of the ring in relation to the barrel, or vice versa, so that the top of one side of the ring was level with the bottom of the opposite side of the ring, would effectively increase the diameter of the ring by about 1.9mm. Mr Gilbert was asked to estimate the extent of the effective increase of the diameter when he was being cross-examined. Without being able to calculate it, he came up with an estimate of 1.7mm.
Mr Gilbert also gave unchallenged evidence that it was unlikely that the ring would have jammed inside the barrel intermittently.
Grayson's only witness, Mr Daly, gave evidence that Grayson did not have the facilities to make the bearing support ring, and therefore had it made elsewhere and delivered to its factory. Grayson did make the barrel. Mr Daly was not present when the ring was fitted inside the barrel. He said that the only way the ring could have been put into the barrel was by using a crane to lower it into position. Any problem or abnormality in positioning the ring within the barrel should have been reported to him, but he received no such report. He heard no suggestion of force being used to make the ring fit inside the barrel. He did not see or hear anything to indicate that a fit had not been achieved in a normal way. It seems that nobody reported to Mr Daly that the outer circumference of the ring had not been machined, nor that it was not round, nor that the clearances between the ring and the inside of the barrel did not accord with Fulghum's design.
I think it is unlikely, but still possible, that the ring was jammed inside the barrel at Grayson's factory. I think it more likely that the workers there orientated the ring so that it fitted inside the barrel without jamming. They might have needed to rotate it until it fitted. It might, by chance, have fitted from the outset without anyone needing to rotate it. If the workers had thought that a fit could be obtained only by using force, I think it more likely that they would have reported their problem to Mr Daly. I am certainly not in a position to make a finding that jamming occurred at that stage. It was not suggested that I should make such a finding.
Mr Wakeman's opinion is that the ring most likely became jammed inside the barrel when the crane was erected at Hampshire. That is also Mr Gilbert's opinion.
In forming his opinion, Mr Wakeman assumed that the base spool piece would first have been installed and attached to the central pedestal by the anchor bolts, and that the tail piece of the crane, including the barrel, the bearing support ring, and the bearing race, would then have been lowered onto the base spool piece. He postulated that the jamming was likely to have occurred as a result of imprecision in positioning the tail assembly onto the base spool piece. Mr Lewis gave evidence to the effect that the pivot assembly would not have been installed in that way. According to him, the base spool piece would have been installed on the central pedestal temporarily, fixed in position by means of the anchor bolts, but then, after the grout below it had firmly set, removed, and bolted to the bottom of the bearing race. The tail assembly, with the base spool piece attached, would then have been lowered back onto the pedestal and the anchor bolts re-installed. I do not think it makes much difference whether the assembly procedure was that described by Mr Lewis or that assumed by Mr Wakeman. Either way, there was a chance that, when the tail assembly of the crane was lowered onto the central pedestal, there would be an impact sufficient to tilt the bearing support ring inside the barrel and jam it very firmly in a tilted position. I see no reason why the risk of such an impact would have been lower if the base spool piece was attached to the crane, rather than the pedestal, at the time of impact.
According to Mr Daly, the ring weighs at least 60Kg. Obviously a substantial force would be needed to jam an item of its size and weight inside the barrel. Some witnesses spoke of the need for a substantial "moment". The relevant definition of "moment" in the Macquarie Dictionary reads:
"product of force times distance the product of a quantity such as a force multiplied by its perpendicular distance from a given point".
For present purposes, I think it is sufficient for me to refer to the required force, rather than the required moment. A force sufficient to jam the bearing support ring inside the barrel could have been exerted by workers at Grayson's factory without Mr Daly's knowledge, but I think that unlikely. A sufficient force could have been exerted if the tail assembly had not been lowered onto the pedestal gently and accurately. The defendants contend that a sufficient force could have been exerted at the time the crane collapsed, and that that is when the jamming must have occurred. All parties appear to accept that a force sufficient to cause the jam could not have occurred during the routine use of the crane. There is no suggestion of any other untoward event that might have caused the jam. The ring was so firmly jammed inside the barrel that Mr Wakeman found it necessary to use jacking techniques to get it out.
After the three anchor bolts fractured in February 1998, some of the grout on the top of the central pedestal was removed and replaced as part of the repair process. When the broken flanged base spool piece was inspected following the collapse of the crane, it was found that some of that new grout was inside the crack that had caused the collapse. That is to say, the cracking had begun prior to the February 1998 repairs. I think it must follow that the forces that caused the collapse of the crane were the same forces that caused the three anchor bolts to break about four months earlier.
After the bearing support ring was removed from the barrel, the upper neoprene ring was removed, inspected and photographed. Mr Wakeman wrote the following about it in a report dated 2 July 1998:
"Prior to removal of the retaining ring it was noted that the top neoprene rubber was substantially compressed on one side and was protruding into the inside of the bearing ring over an arc of some 90 degrees ie the bearing ring and bearing assembly were firmly wedged inside the welded ring at an angle to the base plate and the top rubber ring was compressed towards one side. … The neoprene ring was subsequently noted to have been permanently deformed over about half of the circumference (refer photographs Attachment 7, note rubber extruded into bearing attachment holes) giving the first indication that the tilting and jamming of the ring had been of long duration probably since the original construction."
The bearing support ring has a series of vertical holes in it, several centimetres inside its circumference. The pattern of marks on the upper neoprene ring indicates that neoprene forming part of the ring was extruded into a number of those holes. The strength and/or duration of the force that caused those extrusions must have been so great that the ring was permanently deformed. The defendants' case is that the neoprene ring was deformed not as a result of jamming, but as a result of the state of the rail. Having regard to Dr Kahn's reports and the evidence I have referred to as to the state of the rail and the likely extent of the resulting compression of the neoprene, I reject that contention. In my view the condition of the neoprene ring very strongly suggests that the bearing support ring was jammed in the barrel for a very long time before the collapse of the crane. Mr Wakeman and Mr Gilbert gave evidence to that effect, and I accept that evidence.
A lot of evidence was given at the trial about marks on the bearing support ring, which was tendered as an exhibit. There are a number of marks around its circumference. The possible causes of such marks include (a) flame cutting; (b) rust; (c) the impact of the ring striking the inside of the barrel as a result of the exertion of horizontal forces; (d) impact at the time of jamming; and (e) movement of the barrel against the ring or vice versa (if movement was possible). Mr Lewis gave evidence that some of the marks were of such a nature that they must have been caused by movement. If that was correct, the ring could not have been jammed prior to the collapse of the crane. Mr Wakeman conceded under cross-examination that it was possible that some of the marks on the circumference of the ring corresponded with marks inside the barrel. Before forming the view that the condition of the neoprene ring indicated a jam of long duration, he had thought that some of the marks on the ring and barrel had been caused by them moving against one another. Mr Stanford conceded that the marks could be consistent with metal pieces impacting or rubbing. Mr Gilbert said that the state of the neoprene ring was the only thing that led him away from thinking that the marks on the bearing support ring had been caused by impact between it and the barrel.
After inspecting the marks on the bearing support ring and considering all the evidence of the witnesses in relation to those marks, my conclusion is that some of the marks are of such a nature that they could have been caused by the two parts rubbing or impacting against one another, but that none of the marks is of such a nature that such rubbing or impact is anything more than a mere possibility. There is nothing about the marks to suggest that movement must have caused them, or was the most likely cause of them.
Mr Wakeman's report of 2 July 1998 includes photographs of four marks inside the barrel. They prove just as little as the marks on the bearing support ring. It is possible that they could have been caused by movement of the barrel against the ring, or vice versa, but there is nothing about them to suggest that any such movement must have occurred, or is likely to have occurred.
The lower neoprene ring was not distorted. However, in my view, that fact does not help the defendants. If the bearing support ring was jammed in the barrel, with one side of it so far inside the barrel that that side of the upper neoprene ring was compressed and deformed, it does not necessarily follow that the opposite side of the bearing support ring would have been out of position, or so far out of position as to compress and deform that side of the lower neoprene ring.
As I have said, the defendants contend that the jamming occurred as a result of forces that were exerted when the crane collapsed. However Mr Wakeman gave evidence that the forces exerted at that time were largely vertical forces that went straight up, in line with the line on the attached sketch that is marked "centreline of pivot". In a report that was tendered as an exhibit, Mr Gilbert said that the barrel and the ring were "sufficiently remote from the failure point that they would not have been subjected to undue loadings". However, under cross-examination, he conceded that it was possible that, when the flanged base spool piece broke into two parts, the upper part might have rotated in such a way as to cause the bearing support ring to rotate inside the barrel. It may be that the nature and strength of the forces exerted at the time of collapse were capable of causing the bearing support ring to jam in the barrel, if it were not already jammed. However, as I see it, the weakest aspect of the hypothesis that the collapse caused the jam, is that the evidence does not suggest any possible cause for the collapse if there was no pre-existing jam.
It was suggested at the trial that Mr Wakeman's jacking operation might have deformed the barrel or the bearing support ring. Mr Wakeman disagreed with that hypothesis. Mr Gilbert's response was, "It is possible but I actually doubt it." In my experience, when scientists and engineers give evidence they often readily concede particular hypotheses to be possibilities, even when the likelihood of particular hypotheses being correct is very slight. Even if some deformity were caused by the jacking process, the bearing support ring and/or the barrel must first have been sufficiently at variance from Fulghum's design for a jam to have occurred.
As I have said, all of the witnesses at the trial had had substantial experience in engineering. They all gave their evidence confidently. Because Mr Lewis expressed the opinion that poor rail maintenance, not jamming, was responsible for the collapse of the crane, and because I have rejected that hypothesis, I think I should treat all of his expert opinion evidence with caution.
There were a number of shortcomings in Mr Wakeman's evidence. In his evidence-in-chief he said he believed the rear section of the crane weighed "some 35 tonnes", but under cross-examination he accepted that its weight was probably more of the order of 15 tonnes. He thought that the flanged base spool piece would have been attached to the base of the crane when it was lowered on to the central pivot, but the evidence of Mr Lewis to the contrary was supported by a sensible explanation: it was much easier to bolt the flanged base spool piece to the bottom of the bearing race when it was not attached to the central pedestal. When viewing a photograph of the bearing support ring, Mr Wakeman mistook a weld joint for a paint mark. In his evidence-in-chief he estimated that the extrusions of neoprene into the vertical holes in the bearing support ring extended over an arc of about 120 degrees. A little later his estimate was 120 degrees to 150 degrees. However the passage that I quoted above from his report of 2 July 1998 revealed that those extrusions extended over an arc of only about 90 degrees. It emerged during his cross-examination that he had forgotten that the presence of grout from the February 1998 repairs indicated that the crack in the flanged base spool piece had already begun to form before the three anchor bolts broke. All of these things indicate that Mr Wakeman had not fully refreshed his memory before coming to Court to give evidence. However, I do not think it follows that his opinions, formed after carefully considering all the available evidence in 1998, are any less reliable than they would have been if his memory had been perfectly and thoroughly refreshed.
Before realising the extent of the deformity of the neoprene ring, he had expressed the view that marks on the bearing support ring and the barrel had been caused by them moving against one another. He changed his mind after looking at the neoprene ring. I think it can fairly be said that he jumped to a conclusion before he had considered all the evidence, and that he found it necessary to change his mind once all the evidence was available. However, I do not think it follows that his original conclusion was likely to be correct, or that his ultimate conclusion is any less reliable than it otherwise would have been.
The criticisms that can be made of Mr Wakeman do not apply to Mr Gilbert. He was the most independent expert in this case. His conclusions are substantially in accord with those of Mr Wakeman.
In his report of 2 July 1998, Mr Wakeman ruled out all possible causes of the collapse of the crane other than a jamming of the bearing support ring inside the barrel at or before the time of the erection of the crane at Hampshire. That reasoning accords with the approach that a court should take to circumstantial evidence: Chamberlain v R(No 2) (1984) 153 CLR 521. In my view the reasoning and conclusions of Mr Wakeman and Mr Gilbert cannot be faulted. On the basis of their expert opinion evidence, I am satisfied that the bearing support ring was jammed inside the barrel, at least from the time that the crane commenced operations in March 1995; that excessive forces were generated as a result; and that these forces caused the breaking of the three anchor bolts, the failure of the flanged base spool piece, and the collapse of the crane. I am not able to make a finding as to when the ring became jammed inside the barrel. However I am satisfied on the balance of probabilities that that must have occurred either when the ring was installed inside the barrel at Grayson's factory or when the crane was installed by Fulghum onto the central pedestal at Hampshire.
I am satisfied that the neoprene ring became distorted and ceased to function as a result of the ring being jammed inside the barrel. I am satisfied that, as a result of the failure of the neoprene ring, forces that it would otherwise have absorbed or very substantially reduced were transmitted to the pivot mechanism and the anchor bolts. These would include forces generated as a result of the level and radius of the rail circle being slightly outside the tolerances prescribed by Fulghum, and a result of "pumping" of the rail. However I do not regard those forces as being substantial or effective causes of the collapse of the crane since they should have been rendered innocuous, and were not significantly greater than those that would have been generated if the appropriate tolerances had been strictly respected. In my view the sole substantial and effective cause of the collapse of the crane was the jamming of the ring inside the barrel.
Liability of Fulghum
It is admitted on the pleadings that the plaintiff's contract with Fulghum required the crane to be constructed, supplied and installed in accordance with Fulghum's design drawings, and that one of those drawings required the internal diameter of the barrel to be uniform at 1118mm, and required the bearing support ring to be machined. It is admitted that drawing A1 1012–122-2A was one of the relevant design drawings. That drawing has been tendered as an exhibit, and shows that the bearing support ring was required to have a uniform diameter of 1111mm. It follows that Fulghum committed breaches of the contract by constructing, supplying and installing the south crane when (a) the internal diameter of the barrel was not a uniform 1118mm; (b) the circumference of the bearing support ring was not machined; and (c) the diameter of the bearing support ring was not a uniform 1111mm. It was as a result of those breaches of the contract that the ring could and did jam in the barrel, and that the crane consequently collapsed. Those consequences were likely and foreseeable. Fulghum is therefore liable to pay the plaintiff damages for breach of contract in respect of the collapse of the crane.
The quantum of such damages has been admitted in the sum of $315,878.79. The plaintiff is unable to claim damages against Fulghum in respect of interest losses in accordance with Hungerfords v Walker (1989) 171 CLR 125 since there is a clause in the contract that precludes such a claim.
Liability of Grayson
It is admitted on the pleadings that at all material times Grayson knew that the cranes were being designed, supplied and installed by Fulghum for the plaintiff. It is also admitted on the pleadings that Grayson was at all material times experienced in the fabrication of log handler cranes. Having regard to the engineering evidence that I have referred to, it is clear that it was reasonably foreseeable on the part of Grayson that defective fabrication of parts of the crane could result in jamming and even its collapse. It follows that Grayson owed the plaintiff a duty to take reasonable care to ensure that the parts that it fabricated did not vary significantly from Fulghum's design. I am satisfied on the balance of probabilities that the dimensions of the barrel and the bearing support ring, when they left Grayson's factory, were approximately as measured after the collapse of the crane. I find that Grayson breached its duty of care by providing parts with those approximate dimensions, and with the outer circumference of the ring not having been machined. It was because those parts had those defects that they jammed and the crane collapsed. It follows that Grayson is liable to pay the plaintiff damages for negligence.
As against Grayson, the plaintiff claims $315,878.79 plus $23,000 interest. As to the interest claim, it is agreed that, as a result of incurring repair costs, the plaintiff incurred interest losses in the sum of $23,000. Subject to any reduction for contributory negligence, it is therefore entitled to recover both the sums claimed against Grayson.
Contributory negligence
The primary basis upon which the defendants have pleaded contributory negligence concerns the maintenance of the rail. I am satisfied on the balance of probabilities that the state of the rail made no significant contribution to the collapse of the crane.
The defendants also contend that the plaintiff was negligent in failing to detect the crack in the pivot base pedestal, and in failing to investigate properly or at all the causes of the failure of the three anchor bolts.
As I have said, the crack in the flanged base spool piece began to develop prior to the failure of the three anchor bolts. I received no evidence to suggest that the plaintiff ought to have been aware of any abnormal problem with the crane prior to those bolts breaking. I therefore am not satisfied that it was negligent in failing to detect the crack before they broke.
After they broke, although Fulghum provided advice as to repairs and those repairs were undertaken, it seems that nothing was done to attempt to identify the cause of the bolts breaking. The crane was load tested on occasions, but the plaintiff's standard safety procedures required there to be no pedestrians inside the rail circle when the crane was being operated. The plaintiff blindly adhered to that safety requirement during the load testing, with the result that nobody looked at the pivot mechanism while the grapple was lifting a load.
This was a very expensive piece of machinery. The failure of three anchor bolts should have suggested that something was very seriously wrong with it. It appears from a report of Mr Lewis dated 20 September 2006 that the anchor bolts had the capacity to tolerate forces 16 times those that would be expected to result from the routine operation of the crane. The plaintiff's management should have realised that, upon the broken anchor bolts simply being replaced with stronger ones, something else was likely to fail in due course. Mr Wakeman conceded that close inspection following the failure of the anchor bolts would have revealed the crack in the flanged base spool piece. Under re-examination, with the benefit of hindsight, he conceded that there should have been a more detailed investigation. He said he thought that would have led him into the pivot, and that he would have found the bearing support ring skewed and jammed. In my view, the collapse of the crane would have been avoided if the plaintiff had undertaken appropriate investigations following the failure of the anchor bolts.
In my view, the primary responsibility for the collapse of the crane lies with the defendants, since they were responsible for the fabrication and supply of the defective barrel and ring, and since Fulghum was responsible for the installation of the crane. So far as the failure to investigate the cause of the failure of the anchor bolts is concerned, I consider it significant that the plaintiff looked to Fulghum for advice following their failure. Taking those matters into account, I think it would be just and equitable to reduce the plaintiff's damages by 15 per cent because of its contributory negligence.
Conclusion
For these reasons, judgment will be entered for the plaintiff
(a) against both defendants for the sum of $268,496.97; and
(b) against the second defendant for a further sum of $19,550.
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