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At the present time there are rapid changes occurring in the fleets of transit buses that are used in cities. These changes involve improvements in conventional diesel buses, Compressed Natural Gas, CNG, and more recently hybrid electric vehicles. In order to evaluate the performance of the transit buses, driving cycles have been developed, and two of the most popular are the New York City, NYC, and the Central Business District, CBD. These cycles have proven to be very valuable for predicting both performance and emissions of the transit buses, however they do not well characterize some of the unique characteristics of certain cities, such as San Francisco with its hills and high grade. In this paper we present the results of Chassis dynamometer measurements and modeling of the performance of four different types of transit buses on the typical grades that exist in San Francisco.