Abstract
This paper reviews calculation tools available for quantifying the greenhouse gas emissions associated with different types of public transit service, and their usefulness in helping a transit agency to reduce its “carbon footprint” through informed vehicle and fuel procurement decisions. Available calculators fall into two categories: registry/inventory based calculators most suitable for standardized voluntary reporting, carbon trading, and regulatory compliance; and multi-modal life cycle analysis calculators that seek comprehensive coverage of all direct and indirect emissions. Despite significant progress in calculator development, no single calculator as yet contains all of the information needed by transit agencies to develop a truly comprehensive, life cycle analysis-based accounting of the emissions produced by its vehicle fleet operations, and for a wide range of vehicle/fuel technology options.