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The words of Spanish born, American philosopher George Santayana - “Those who fail to learn from history are doomed to repeat it” - resonated in my mind as I was called to a site who had just had a repeat incident involving a heavy vehicle tyre explosion. The first incident sadly resulted in a fatality. The second incident resulted in catastrophic injuries to the young worker and he will never work again after sustaining a traumatic brain injury during the incident which resulted in cognitive, behavioural and physical disabilities.

Given that the raison d'être of incident investigations are to prevent recurrence, reduce risk and advance safety, the question had to be asked why the learnings from the first incident did not achieve the aims. To be blunt, if a site cannot learn from a loss like a fatality, you wonder what will motivate them (and indeed if they merit operating sanctions…).


The two incidents were startling in their similarities, despite the fact that they occurred several years apart. Both incidents occurred while the workers were attempting to repair heavy vehicle rims. On both occasions the workers were alone at the time and both of them, for reasons difficult to fathom, had breached safe work procedures in performing what many might consider a high risk task.

The terrible consequences of heavy vehicle tyre explosions was well known in their industry and both had undergone training which made specific mention of the inherent risks and previous significant incidents. Yet, both operators had short-cut the safe system of work by not removing the tyres from the rims before attempting repairs, not using a safety cage during inflation after the repair work and not adhering to the mandated exclusion zone, which in effect led to them standing directly in the “line of fire” when the tyres exploded.


Heavy vehicle truck tyres are significantly larger and are designed to operate under much higher pressure than regular car tyres, increasing the risk associated with an exploding tyre. Many workers over the years have been seriously injured or killed by blasted parts of a tyre and rim assembly or by the sheer force of violent air pressure ruptures.

Life changing injuries from previous significant incidents have included permanent damage to hearing and eyesight, traumatic brain injuries and amputations. Tragically, the sheer volatile force during a tyre explosion has also led to many deaths when workers have been struck by components of the tyre or rim or killed by the explosive force when air pressure from a pressurised tyre ruptures.


A tyre explosion is significantly different to a tyre blow-out. A tyre blow-out or tyre burst occurs when the casing of the tyre cannot hold the inflated pressure. This usually occurs when the tyre casing is weakened due to events like running over a big rock or due to a manufacturing defect. Tyre blow-outs can occur when the plant is moving, stationary or when the tyre is being inflated. To mitigate against over-inflation, most manufacturers of heavy vehicle tyres now have a safety factor of 2 to 1 (which means if an undamaged tyre had a psi rating of 100, it potentially could be inflated up to 200 psi before it would fail).

A tyre explosion on the other hand, is an explosive reaction involving energy many orders of magnitude greater than that of a tyre blow-out. A shock wave creating pressure in excess of 1000 psi causes a tyre explosion. This type of event can occur due to contact with high voltage power lines, fires, lightning strikes or application of heat to tyre components (from over-heated brakes or welding for example).


Due to previous incidents, codes of practice and safe working procedures etc., it is a universally accepted protocol that under no circumstances should hot work be carried out on any wheel to which a tyre is fitted to avoid a chemical reaction called pyrolysis, which can occur when a rubber tyre becomes overheated. Pyrolysis causes the rubber to deteriorate and at a certain point, this deterioration can create a very rapid pressure increase inside the tyre that can lead to a sudden and unexpected explosion.

Despite these well-known protocols and despite the two operators being aware of the safe working procedures for their site which specifically stated that tyres must be completely deflated and removed from the rim before work on wheel assemblies, both operators had simply deflated the tyres a bit and pushed them back before performing hot work on the rims.

Forensic examinations showed on both occasions, this practice resulted in pyrolysis occurring. Often, there are no visible signs when pyrolysis is taking place until the explosion occurs. Due to the chemical reactions taking place, the pressure inside the tyre can increase to over 7,000 kPa (1,000 psi) before an explosion occurs. Anyone standing in the immediate vicinity is at risk of serious injury or death.


How big can the explosive force be from an air pressure rupture due to pyrolysis? Well in the training program that both of the operators had gone through at the site, a case study was presented about a workshop operator who was welding on a rim assembly when one of the tyres exploded. The operator received fatal crush injuries when he was thrown 20 metres against the workshop wall and pinned by the rim and tyre assembly.

Just last year, yet another worker was killed with the circumstances illustrating the sheer explosive force of a heavy vehicle tyre rupturing. The operator was struck in the face by an exploding wheel and tyre, with initial inquiries indicating that he was attempting to weld up a small leak in the truck wheel, while the tyre was still pressurised. The welding appeared to cause an internal combustion, blowing the wheel off the tyre. The wheel hit the worker, killing him instantly, before travelling 5.5 metres into the air, going through the roof and landing some 23 metres away.


You can imagine that following Incident #1, the site conducted an extremely thorough investigation. Of course, there was also involvement from the regulator and all in all from an industry perspective, it appeared that much was going to be done to ensure this type of incident would never happen again.

Just some of the key recommendations focused on appropriate safe systems of work, suitable training and competencies, use of safety cages or other portable restraint devices prior to inflating tyres, exclusion zones outside of trajectory paths and remote gauges and long air hoses to ensure there was no need for operators to venture into exclusion zones. In addition, the site initiated a rule that there would be no sole working in workshops when wheel assemblies were being repaired as well as establishing an annual stand down day for the site to focus on safety and the key learnings from the tragic loss.


So given that Incident #2 was practically a repeat of Incident #1, what went wrong to allow such a tragedy to reoccur? The investigation into Incident #1 was assessed as being thorough. Data collection was comprehensive and the data analysis was assessed as being of a high standard. The recommendations which addressed the deficiencies identified in the analysis certainly appeared to meet the objectives of prevention of recurrence and reduction of risk.

The big problem was the transition between recommendations on paper and corrective actions actually being done, both in the short term and long term. Immediately following Incident #1, a Safety Alert went out across industry. At the site, there was a comprehensive “re-training” and certification program. New equipment was bought, protocols and safe working methods were audited and monitoring of the minimum two worker rule during any work on wheel assemblies was stringent.

A year after Incident #1, the site’s annual safety stand down day was proclaimed to be a success, with all personnel identifying how the key learnings from Incident #1 (e.g. adherence to safe systems of work, using appropriate equipment and avoiding “line of fire” positions) could be applied to their specific job / operation.

Two years after Incident #1, the impetus was still apparent on site. Posters were produced after the second safety stand down day highlighting how personnel had identified three major categories of line of fire incidents – “caught in or between” (e.g. placing hands too close to a rotating gear), “struck by” (e.g. hit by a moving vehicle or falling object) and “released energy” (e.g. like tyre explosions or pipes releasing hot steam during valve removal).

Three years after Incident #1… well, let’s just say that time has an unfortunate habit of diluting safety measures sometimes. Just three years after Incident #1, the focus and effort seemed to drift away. The Site Manager decided that as it was a particularly busy operational time, the safety stand down day would be deferred indefinitely (and as it turned out, they never had another one). Personnel shortages resulted in the two person rule in the workshops while working on wheel assemblies being relaxed and site expansion resulted in some workshops not having the same equipment as others.

Many of the personnel who had been at the site when the fatality occurred had moved on and the organisation had no structured, effective means of retaining corporate history. Paper records were archived, facilitators of training programs were not conversant in the specifics of Incident #1 or were not even aware of it, equipment was not maintained or went missing and of course, the push was always on for operations and production.

In effect, three years after Incident #1, the site had moved on. It was sad to find that following Incident #2, the majority of the personnel interviewed were not even aware that their site had suffered a similar incident resulting in a fatality several years prior.


So what can we do to ensure that sustained learnings occur following a significant event? In short, organisations need to ensure at the absolute minimum they retain corporate and operational history and there needs to be an effective incident learning system.

It’s not enough for any organisation to state that they have an incident management system with a record of recommendations. Far too many companies have a close out system where as soon as the Approving Officer signs off to approve a Recommendation, then effectively it can just be closed out. There are no checks and balances to ensure a) the action was indeed done, b) the action was effective and c) the change/s would be sustained.

No organisation wants to learn a safety lesson the hard way through a tragic loss. But to have it happen twice is reprehensible. The Flight Safety Foundation said it best in the 1980’s with this quote: “To have an accident is unfortunate, to have an accident and learn nothing from it is unforgivable.” Flight Safety Foundation.


So how does your organisation measure up? Are you confident you’ll never be tortured by the phrase “Those who fail to learn from history are doomed to repeat it”?

Some simple indicators to think about:

Do you have a process for ensuring that the findings of incident investigations and analysis of data is acted upon and recommendations are actioned to prevent recurrence of incidents?

  • Do you have a process for validating recommendations are appropriate, are based on the hierarchy of control and are actually implemented?

  • Do you have a process to review / evaluate the operational effectiveness of recommendations after they are implemented?

  • Do you have a process to ensure that on-going monitoring and auditing is conducted to ensure that recommendations involving changes to safe systems of work are sustained and do not revert back to the pre-incident state?

  • Do you have a process for disseminating information on incidents and corrective actions to all relevant parties (both internal and external) so lessons can benefit others both within your organisation and further afield in industry?

  • Do you have a system to record incident information in a format that is readily searchable and retrievable to allow ease of access, so that any lessons learned stay learned (i.e. corporate memory)? Are the reasons for changes known and documented?

  • Do you have protocols in place to ensure that operational or production pressures do not result in incompatible goals with safety processes implemented after an incident?; and

  • Ultimately, do you have processes in place to ensure that the lessons from tragic losses live on, leaving a legacy to protect others from the same fate?

Interested in Knowing More?

Further information on Safety Wise’s Incident Cause Analysis (ICAM) Training is available from our website:

Additional ICAM Related Services

Safety Wise also offers the following additional services for sites that adopt the ICAM investigation analysis method:

  • Quality review of incident investigations using ICAM

  • Trend analysis of organisational factors contributing to serious incidents

  • Participation in investigations as an external / independent party


Jo De Landre

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