Injaka - Lesson Learned

Injaka Bridge Collapse: Lessons Learned

By Terry Deacon, ProjectPro

The Injaka Bridge in Mpumalanga collapsed on 6 July 1998, causing the death of 14 people (including the designer of the bridge, Ms Marelize Gouws) and injuring 19 others. Most of them were standing on the bridge deck as it was being launched.

The owner of the works was the Department of Water Affairs and Forestry. VKE Consulting Engineers were appointed by the owner to design the bridge to span the Ngwaritsane River, near Bosbokrand.  The contractor, Concor Holdings (Pty) Limited, was appointed to design the temporary works from design information obtained from VKE and to build the structure.

The bridge was a seven-span continuous structure with an overall length of 300 meters and was designed to be constructed by means of the incremental launching method. A steel nose was attached to the leading end of the first segment. Its function was to reduce the cantilever moment, the corresponding shear force and bearing reactions during launching. To enable the bridge to slide on top of the supports during the launch, temporary sliding bearings were used in combination with the permanent bearings.

After 4 years of investigation, the Injaka Bridge collapse inquiry in terms of the provisions of section 32 of the Occupational Health and Safety Act was at last made public in mid May 2002.

The purpose of the inquiry was twofold: 

  • to determine liability for the accident
  • to gain experience for preventing similar disasters in future.

Adv Hans Fabricius and his legal team found both parties, the consulting engineers and the contractor, negligent in a number of ways. Johan Bischoff, head of VKE Pretoria structural department, and technical manager Rolf Heese of Concor, were both found to have been negligent.

Cause of collapse

The causes of the collapse resulted from a long list of shortcomings and can be summarized as follows:

  • Lack of competent personnel and supervision
  • Steel launch nose not structurally stiff enough
  • Incorrect temporary works slide path
  • Incorrectly placed temporary bearings
  • Incorrect feeding of bearing pads
  • Under-designed deck slab

All of the above could have been avoided had normal design and project management principles been applied.

Cracks appeared in the bridge deck as warning signs that things were going wrong, but they were not taken seriously by anybody. The first type of crack was the longitudinal cracks close to the corner of the box observed by a Mr Khanyile (Concor pad feeder). These were tensile cracks and it showed that the western haunch had been failing for a long time. The other transverse cracks were seen by Concor’s Mr De Sa and Mr Jordao.  These were reported during his first few days on site.

Mr Bischoff mentioned that cracks were a serious matter and that their sizes and positioning were indications of the degree of seriousness. He did some calculations by looking at the reinforcement within the diaphragm and believed that it was reasonably correct. He then gave the instruction that the launch be proceeded with and that the destressing be done. A reasonable contractor would not have proceeded with the launch of an undamaged deck in these circumstances, much less would a reasonable contractor have proceeded with the launch after such damage had been discovered, regardless of what the engineer may or may not have approved at that stage. 

Mr Martin, an expert witness, mentioned that if he had seen the cracks and the problems with pad feeding, he would have been sufficiently alarmed to have moved the people off the deck on the day of the collapse. Mr Oosthuizen, another expert witness stated, “When one sees such a crack, you will see trouble".

There had been many warning signs and that with experienced staff and adequate controls and alarms, the collapse of the bridge could have been prevented.

The event that triggered the collapse of the Injaka Bridge was a punch-through of the bottom slab of the bridge deck by one or more of the bearing pads on top of the western bearing at pier 2. Once this happened, the collapse of the entire bridge was inevitable and would have followed regardless of any other defects that may have existed in any other part of the structure, including the inadequate steel nose.

The principal cause of the bearing pads and bearings punching through was the placement of the temporary bearings underneath the bottom slab of the deck, rather than in their most favourable positions, i.e. substantially under the webs of the deck section. But if the permanent works drawings were defective or unclear in this regard, one would at least expect the relevant project specification to be clear.  It seems to be entirely unnecessary to expect the contractor to have to work out where to place his temporary bearings, based on inferences drawn from his interpretation of obscure clauses. It remains a mystery why the exact sizes and positions of the temporary bearings cannot be given to the contractor, if not by way of drawings, then at least by way of a clearly formulated project specification.

A long legal battle

The inquiry commenced in January 1999 and the evidence was completed on 30 November 2001.

Dept of Labour presiding officer, Larry Kloppenborg, explained that the inquiry took such a long time to complete due to the complex nature of the case. VKE and Concor appointed 9 experts between them and the Department of Labour appointed another 2. The application for a High Court interdict to halt the investigation brought by VKE in late 1999 also slowed down the process.

There was a great deal of debate, often unnecessarily acrimonious, on the topic of each party's responsibility for his particular contractual duty and field of expertise in the context of temporary and permanent works.

The inquiry sat for about 196 days during this three-year period and various delays were occasioned.

VKE brought three applications in the High Court during this period. The attitude of VKE throughout the inquiry and until the final court application during November 2000, namely that it was entitled as of right to be granted sufficient time to study the expert reports of the other interested party, Concor, before it was obliged to submit its own reports and to give evidence.  The source of this alleged right has never been provided to the inquiry and of course no such right existed.

Further delays resulted from the inability or refusal of the experts to have a meaningful pre-hearing conference to identify areas of dispute and areas of agreement. 

The inquiry found both VKE and Concor to blame for the collapse of the bridge. But this is not the end of the matter, since both VKE and Concor are legal entities (not natural persons) who acted through their employees and/or directors. The question arises as to which of those employees or directors should or might be held responsible for the acts and omissions of Concor and VKE, respectively. In this regard, it is not concerned with contractual liability, but with potential delictual or criminal liability for the deaths and injuries resulting from the collapse.

In the context of this lack of experience, mention must again be made of the principle embodied in the maxim imperitia culpae admuneratur which, taken literally, means that ignorance or lack of skill is deemed to be negligence. This principle applies where a person undertakes an activity for which expert knowledge is required while such person knows, or should reasonably know, that he/she lacks the requisite expert knowledge and should therefore not undertake the activity in question.

Findings of the inquiry

Adv Fabricius said the root cause of the problem was inexperienced and unsupervised staff, “We are convinced that, if either of the two parties had appointed suitably qualified and experienced persons to design the permanent works and to design or review the design of the temporary works, this tragedy would not have happened.”

It was stated that although Ms Gouws, had limited site experience, she was responsible for the design of the bridge, and would thus provide valuable input to the site team. It seems that she was an excellent student. She had limited experience in bridge design though, as can be expected considering that she had only obtained her Bachelor degree in civil engineering in 1995.  At the time of the collapse she was busy with an Honours degree in structural engineering and had not yet been registered as a professional engineer.

Mr Burger (VKE director) testified that a design review of the Injaka project did not take place. Dr Zietsman said that this was not acceptable to him and that there should have been an audit of the bridge design.

Predictably, Concor and VKE both blamed each other for the fact that the slide path and the temporary bearings were not where they should have been. VKE’s point of view was that it is the engineer who chooses the slide path, that they had done so and that they had informed Concor of their choice in the project specifications. According to them, Concor did not comply with these specifications, by putting the slide path and the temporary bearings in different positions than those indicated in the project specifications.  For this they are allegedly solely to blame.  Concor, on the other hand, contended that the positions of the slide path and the temporary bearings were either not properly indicated by VKE, or indicated to be in the positions in which they were constructed by Concor. More importantly, however, VKE, by approving the temporary works, accepted the slide path and temporary bearing positions indicated by Concor.  Having done so, the responsibility for the incorrect bearing positions lies with VKE.

It was the inquiries opinion that neither of the aforementioned approaches is correct, and that VKE and Concor must share responsibility for the incorrect positioning of the slide path and the temporary bearings.

Although it may be true, as VKE contended, that their approval of Concor’s defective work does not absolve Concor from responsibility, that says nothing about its own responsibility. VKE had various responsibilities in terms of its contract with the Department.  Its responsibility was not limited to the design of the permanent works.  It was also responsible to supervise Concor’s work. The purpose of such supervision was plainly to ensure that Concor complied with its contractual obligations towards the Department.  Whilst it is accepted that it did not entail an inspection and approval of every little detail of Concor’s work, it is inconceivable that even VKE could realistically have thought that they were not, at the very least, required to satisfy themselves that Concor had complied with one of its most fundamental obligations in terms of the contract, i.e. to place the slide path in the position designed by VKE. It was common cause that the engineer chooses the slide path in an incrementally launched bridge.  If this is so, we can think of no reason why the engineer should not indicate this important part of the design clearly on the drawings.

In this context it must be remembered that, although the design of the temporary bearings formed part of the temporary works, the slide path was contained in the bridge deck, which formed part of the permanent works designed by VKE.  Even if VKE seriously believed that it was under no obligation to supervise the temporary works - which the inquiry found difficult to believe - they would therefore still have been under an obligation to satisfy themselves that the slide path chosen by them had been correctly constructed by Concor. This they did not do.

Concor’s incorrect pad feeding during the launch (a contributory factor to the collapse) was solely attributable to a lack of adequate supervision of the activities of the pad feeders by suitably qualified persons. The evidence in this regard was that it was explained to the pad feeders before the first launch how the pads had to be fed.   On the day of the collapse, even the more “experienced” pad feeders were unskilled labourers. Nevertheless, it was left to them to explain to the other pad feeders, some of whom were only employed for the first time that day, how to feed the pads and to supervise them.  Having regard to the importance of correct pad feeding, this was wholly unsatisfactory. To entrust such an important task to unskilled labourers who had absolutely no appreciation of the importance of performing their tasks strictly in accordance with their instructions and to then assume that they would comply with those instructions without any real supervision, is unacceptable and in fact amounts to negligence.

The inquiry gave a great deal of thought to the question whether any other Concor employees or representatives can be held responsible for the collapse. For example, should the pad feeders be held responsible for their incorrect pad feeding, despite allegedly having been instructed to feed them correctly? Or should Mr Jordao and Mr De Sa be held responsible for the inadequate supervision of the pad feeders and the absence of a proper launching procedure? Or does the responsibility for what happened on site ultimately lie with the site agent?  It may even be argued that Mr Serman (Concor contracts director) and Mr Wardhaugh (Concor contracts manager) should bear some responsibility for entrusting the design of the temporary works to Mr Heese and the construction of the bridge to inexperienced site staff like Messrs Price (Concor site agent), de Sa and Jordao.

All things considered, however, it would be unfair to lay the blame at the doors of the persons mentioned. It was not unreasonable for Mr Serman to entrust these matters to Mr Heese, even though he had not yet been involved in an incrementally launched bridge before. Mr Serman was entitled to accept that Mr Heese would act responsibly by, for example, seeking the assistance of an independent expert if required.

In VKE’s case, it appears from the evidence that the design of the bridge was, for all practical purposes, entrusted to Ms Gouws. Since Ms Gouws died in the collapse, she was obviously not able to give evidence and could therefore not defend herself against any allegation to the effect that her acts or omissions caused or contributed to the collapse of the bridge.  For these reasons, and also because it is clear from the evidence that nothing she did, or did not do, can be said to have absolved the VKE’s employees or representatives from liability. What is clear, is that Ms Gouws was largely left to her own devices and did not receive the support and supervision from Mr Bischoff that she could reasonably have expected and probably did expect. His excuse that it was caused by work pressure is, for obvious reasons, no excuse at all.

Hindsight shows that it was unwise for Mr Rautenbach and Mr Burger (VKE directors in charge) to appoint Ms Gouws as the assistant resident engineer responsible for the Injaka bridge and for Mr Rautenbach to entrust the design of the Injaka bridge to Mr Bischoff. Mr Rautenbach approved the drawings submitted to him by Mr Bischoff for signature without having studied them carefully, and merely on the basis of Mr Bischoff’s assurances that they were in order. Mr Burger approved the temporary works drawings without ensuring that they were in fact compatible with the design of the permanent works. However they should not, the enquiry found, be judged too harshly for this. It was not unreasonable for them to rely on the unequivocal assurances of Mr Bischoff that the permanent works drawings submitted to Mr Rautenbach for signature were in order, and that the temporary works drawings submitted to VKE for checking or review could be approved.

The matter of criminal proceedings against VKE and Concor, or their employees, will now be decided by the director of public prosecutions, whose final report is expected in June 2002. A person is negligent where he/she undertakes an activity for which expert knowledge is required while such person knows, or should reasonably know, that he lacks the requisite expert knowledge, and should therefore not undertake the activity in question (or should not do so without outside expert advice).

Major lessons learnt

“Hindsight is not vouchsafed the common man as he picks his course through life. This must be kept constantly in mind in a case like this one, where all is so obvious now.” - JA Schutz in Durr v ABSA Bank Limited and Another, supra, at 453D-E :

What measures can or should be taken to prevent similar occurrences in future?

It goes without saying that anybody who undertakes the design and construction of such a bridge should be suitably qualified and experienced to do so.

There should always be a design review, irrespective of the identity, qualifications and experience of the designer.  Even the most competent designers make mistakes.  The consequences of those mistakes can be avoided only if another suitably qualified and experienced person checks their work.

The engineer and the contractor should accept responsibility to ensure that there is compatibility between the design of the permanent works and the contractor’s temporary works.

There should be launch procedures and competent staff from the designers and contractors present at the launch to make decisions when warning signs appear.

Nobody should, for safety reasons, be allowed on top of the deck or the nose or even in the immediate vicinity of the bridge while launching takes place, apart from the construction personnel required to perform their duties on top of the bridge deck, the launching nose or in the vicinity of the bridge.

One often hears that the three most important things you can do on a project are to: keep records, keep records, and keep records. However, this will determine the cause of a crisis, but it will not prevent it.

The major lesson learnt from the Injaka Bridge disaster is to: check, check and recheck.

The opinions expressed in this article are not those of ProjectPro Management Services, but are extracted from the text of the Injaka Bridge inquiry by the Department of Labour.

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