An overview of risk issues in compressed natural gas buses

This study assesses the fire safety risks associated with a typical Compressed Natural Gas (CNG) vehicle system, comprised primarily of a school bus and supporting fuel infrastructure. Based on the risk results, the study compares the CNG vehicle safety with that of diesel-powered school buses in the United States. There is general public acceptance of the safety risks associated with diesel and gasoline powered vehicles. Therefore the results of the risk assessment and comparison in this study improve understanding and public acceptance of CNG vehicle safety risks. The primary objective of this study is to assess the safety risks of CNG buses apart from its potential environmental and health benefits. Since not enough accidental and failure events are available from the current CNG bus fleets, direct assessment of risk from historical data and accidents would not be possible. Therefore, this study conducts a model-based risk assessment.