Vaal Reefs Disaster

Vaal Reefs Disaster

Disaster Aetiology Assignment

Abstract

On the 10th May 1995 a tragedy occurred at Vaal Reefs East Gold Mine in South Africa, which was, arguably, one of the most devastating mine disasters to befall the South African mining industry. This assignment hopes to determine the active and latent failures that lead to the causation of this disaster and then classify the human errors that contributed to the aetiology of this tragedy. Finally, my own views will be purveyed with respect to how I think the accident could have been prevented.

Introduction

At approximately 20:12, a driver found a 30 man carriage approximately six meters from the gates of the shaft, followed by a 5 tonne battery locomotive. The driver boarded the locomotive and proceeded as to connect the battery to the power. The locomotive ran away toward the shaft. The operator was unable to stop the locomotive and ejected himself just before the it entered the shaft. The carriage and locomotive entered the No. 2 Main Shaft. The locomotive intercepted a man cage containing 104 miners, which was travelling down the shaft. The falling locomotive and man carriage severed the winding rope attachments on the man cage, in turn allowing the man cage to free fall to the bottom of the shaft. The reasons behind this accident are complex and cannot easily be attributed to one cause.

Active Failures

The definition of an active failure is a failure that has an immediate consequence and are usually made by front-line staff such as equipment operators (HSE, 2015). Active failures usually result in immediate compromise on the health and safety of a process and often precede, or are the direct cause, of an incident. More often that not active failures are a result of a manifestation of latent conditions within the company or organisation, and indeed that is the case with many of the active failures that occurred in this disaster. Active failures are human errors that can further be broken down into intentional failures (cultural and deviant violations) and unintentional failures (slips, lapses and mistakes). The list of active failures that play a role in the aetiology of this disaster is extensive. It is evident from the disaster report, that active failures in this disaster can be broadly broken down into three key areas:

Poor working condition of the locomotive- The electrical condition of the locomotive prior to the accident was nor acceptable or safe. A number of safety devices designed to cut the power to the locomotive under certain conditions were either damaged or not operational, and it was left in a condition that enabled it operational as the magnetic key was bridged out. As a result of this the train could easily runaway. This is an example of a intentional, deviant failure on behalf of the maintenance crews. The electricians responsible for the maintenance also failed to fill out appropriate maintenance log books on time and these were often done in arrears. Furthermore, the log books account that loco 54B was in a ‘good condition’. This is an example of an intentional, cultural failure. The employees in the shift prior to the accident (afternoon shift) identified that the loco was in a ‘dangerous’ state and moved too fast in both directions. They left the locomotive in an unauthorised area near the farm gate and failed to communicate this to the in-coming shift or their superiors. This is an example of an intentional, deviant violation.

Damaged or missing arresting mechanisms- The following is a list of all intentional, cultural failures that contributed to this accident: the farm gate was left open and the cross member left leaning against the sidewall; the aeroplane sprag not in position when the locomotive set off; the tank trap incorrectly set up with the two 600mm sections of rail not in position; the east shaft gate was damaged and left open; and RSJ stop blocks that were intended to replace tumbler blocks (a recommendation made by the inquiry of a similar accident in 1992) had yet to be installed. The mine manager’s decision to disregard the findings of the audit into the safety mechanism of No.2 and hand the responsibility of implementing safety procedure to someone lower down the management chain was an example of an unintentional mistake All of these failures came together at once on the day of the accident rendering the failure mechanism ineffective.

Operator Error- Firstly, the loco driver failed to report the unauthorised positioning of the locomotive to a supervisor, he then secondly performed an unsatisfactory pre-inspection of the locomotive prior to setting off. Finally he inserted the Anderson Plug without application of the brake. Additionally, the driver operated the locomotive in the absence of a guard and failed to ensure the closure of the farm gate and correct positioning of the aeroplane sprag. These actions were all contrary to how the driver had been trained to operate the locomotive. and hence are examples of intentional, cultural violations.

Latent Failures

Similarly with the active failures, there were many latent conditions that contributed to the aetiology of this accident. Latent failures are spawned from decisions that are made by those who's activities are removed in both time and space from the front-line (where they have most impact). Examples of those responsible for such failures are high-level decision makers such as, managers, designers and maintenance personnel (HSE, 2015). This section hopes to link the latent conditions within this scenario to the relevant active failures that resulted.

Poor attitude relating to health and safety procedures- A culture of disregard for incumbent safety protocols by employees at the mine was noticed. Examples of this disregard is the failure of the locomotive driver to carry out the mandatory checks prior to starting the loco; the falsification of log books by maintenance crews; and arresting mechanisms either omitted or incumbent mechanisms left damaged. This disregard to safety procedures were found all over the mines operations and at all levels of personnel, so it is highly likely there existed a laissez-faire culture at management level over adhering to correct safety procedure. Evidence that this culture was widespread throughout all personnel in the mine is shown for instance where the 100 man limit of the shaft cage was exceed and 104 miners were found in to be travelling in the cage, and maintenance employees not filling out log books at the correct time.

Complacency and Cover ups- An inquiry in to the causes of a similar accident in No.2 Shaft in 1992 stated that current arrestor mechanisms