Because of environmental and energy conservation imperatives, the public transit industry is implementing a variety of new technologies, including alternative fuels. Characteristics of these technologies, such as high-pressure fuel storage, have introduced new hazards to the transit bus operating environment. There is no reliable body of knowledge that identifies potential hazards and mitigation strategies for these technologies and their support infrastructure. Thus, there is a need to establish a practical, step-by-step procedure to identify, assess, and mitigate the potential hazards associated with operating, maintaining, and supporting transit buses using alternative fuels.
The objective of this project was to prepare a practical and credible tool for transit managers to assess, and design mitigation measures for, the hazards associated with the use of compressed natural gas (CNG) and liquefied natural gas (LNG). This tool provides a means for quantifying site-specific, fuel-related, hazards and exploring the impact and value of alternative mitigating measures. The scope of the model is limited to transit agency employees, property, and passengers. Environmental cleanup costs from fuel spills and greenhouse gas emissions are not included in this model. It is not intended to present a value judgment on the preference for one technology or fuel over another. Default values for failure rates and consequences are provided for CNG and LNG based on limited survey data available at the time of the study. The model has the built-in flexibility to use site-specific failure rate and consequence data, wherever available, and encourages the acquisition and use of updated industry-wide statistics. An earlier TCRP project presenting a broader analysis of fuel options (Report 38,
Guidebook for Evaluating, Selecting, and Implementing Fuel Choices for Transit Bus Operation) can be found at
https://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=1067.
The
Alternative-Fuel Transit Bus Hazard Assessment Model estimates the consequences (injuries and property damage) and losses (in dollars) from fuel-related hazards (fire and non-fire) on transit buses. The model compares hazards, expected losses, consequences, and mitigation measures within and across fuel types. It is built on quantitative analysis that shows where the key risks for fuel-related hazards in compressed natural gas (CNG) and liquefied natural gas (LNG) are expected. The
Alternative-Fuel Transit Bus Hazard Assessment Model is designed as an Excel spreadsheet tool that can be tailored to the characteristics of a particular fleet and facility after reading the
One-Page User's Guide.
Status: The final report has been summarized in
TCRP Research Results Digest 39. The model and the final report are available on CD-ROM as
CRP-CD-4 through the TCRP Dissemination website at
https://www.apta.com/tcrp.
TCRP Research Results Digest 39, TCRP C-11 Final Report, and the
One-Page User's Guide are also available in portable document format (PDF). Click on the file(s) below to access the document(s). (A free copy of Adobe Acrobat Reader is available at
https://www.adobe.com.) The
Alternative-Fuel Transit Bus Hazard Assessment Model is also available below as a Microsoft Excel spreadsheet.
Research Results Digest 39
CRP-CD-4