Hazard analysis of inland passenger ship operation in Bangladesh using systems theoretic approach

Abstract

Inland waterway is a natural and relatively cheaper mode of transportation in Bangladesh. It carries a significant portion of total arterial freight traffic and passenger traffic in Bangladesh, thereby, contributing significantly to the national GDP. However, every year many people die, get injured and reported missing due to inland water transport accidents. The most significant fact is that accidents involving the passenger ships share the majority of fatality of overall maritime accidents in Bangladesh. However, there have been very limited studies to address this vital issue. Most of the studies conducted on the passenger vessel safety are based on simple statistical approach due to lack of adequate accident data. Therefore, the underlying causal factors behind the accidents had never come into the observation of researchers and stakeholders. The present study attempts to perform a hazard analysis of inland passenger ship operation in Bangladesh by applying the System-Theoretic Process Analysis (STPA) method. This method can identify the causal factors and hazardous scenarios, particularly those related to system design, human behavior and software. In this study, the STPA method is applied in two phases. The first phase investigates the safety of passenger ship operation at inland river terminal. The other phase investigates the safety of passenger ship operation during the voyage. At first, the accidents and associated hazards are identified that are needed to be prevented. Then, a hierarchical control structure of passenger ship operation is designed that captures the functional interactions among different subsystems by modeling the ship operation as a set of feedback control loops. The control structure is then analyzed to identify the Unsafe Control Actions (UCA) by the controllers (concerned personnel of maritime operation). Then, the causal scenarios are identified that describe the causal factors which can lead to the Unsafe Control Actions (UCA) and to hazards. The safety requirements are also determined that can mitigate the factors and eliminate or control the hazards so that accidents can be prevented. The results indicate that most of the UCA exist in the bridge deck of the passenger ship. The most significant category of the causal factor responsible for the occurrence of UCA is the human factor. The successful implementation of the suggested safety requirements can prevent the occurrence of the causal factors and consequently the accidents of inland passenger ships in Bangladesh can be mitigated.