35 / 2021-08-02 18:03:40

Establishment of Braking Hazard Management Procedure (BHMP) for Underground Mine Passenger Carriers: STPA Based Approach

Passenger carriers (PCs), System Theoretic Process Analysis (STPA), Braking Hazard Management system (BHMP)

In present Indian Mining scenario, the use of tyre mounted passenger carriers (PCs) in decline accessed trackless underground hard rock mines is utmost prerequisite for carrying miners from surface to their designated workplaces and vice versa and supporting emergency evacuation etc. The deployment of passenger carriers (PCs) is growing every year. As the PCs are normally used to carry a number of mine workers (more than 10) at a time, occurrence of any accident can give rise to the unfortunate consequences. Thus, the safety of PCs has also engrossed serious attention. Accident/injury records revealed that the failure of braking system is one of the major cause of the passenger carrier related accidents. The quantitative risk assessment based on probabilistic failure analysis (HAZOP- Hazard and Operability study, FMEA- Failure Modes and Effects Analysis etc.) is found inappropriate for solving the problems associated with multifaceted hydro- mechanical structure, complicated component interactions and critical control processes incorporated in PCs. Therefore, a Braking Hazard Management Procedure (BHMP) based on System Theoretic Process Analysis (STPA) is proposed in this research for counteracting hazards arise due to failure of braking system in passenger carriers (PCs). The braking system of PCs (comprising of service brakes and parking brakes allied with Spring Applied Hydraulic Release (SAHR) characteristic) is expected to be made more reliable and fail safe by the application of the proposed BHMP. The brief methodology for establishing BHMP is explained below:

1. Conducting details study on the braking systems of various types of passenger carriers (PCs) and exploration of system safety controls and constraints.


2. Mine Accident Data Analysis (MADA) with respect to accidents comprising PC braking system.


3. Evaluation of present safety management system with reference to brake testing and maintenance procedures of the PC. Establishment of a hazard identification and failure analysis framework for PC’s breaking system, based on STPA.


4. Examination of present control structure, safety constraints and operation process imposed on PCs.


5. Development of BHMP, which will comprise modified control structure, precise control process, imposition of essential constraints, operation strategy and record keeping framework.


6. Implementation of the designed BHMP system and analysis of outcomes.

To assess the expediency of the proposed system, the Braking Hazard Management system (BHMP) for Passenger Carriers deployed in a selected case study underground hard rock mine, had been framed and subjected for implementation. The result is found fairly encouraging. The Passenger carrier, which has suffered six brake failure incidents with four numbers of serious injuries in recent past (From January,2020 to July 2020), has been operated with no minor cases of brake failure problem during last six months of BHMS implantation. Thus, the judicial implementation of the BHMS is expected to reduce maintenance errors, number of accidents and cost of compensations for accidents significantly and also help the mining industry to maintain safe and productive work environment.