CTTransit is hoping to identify the next generation of transit vehicles through its testing of diesel-electric hybrid buses. Emissions and operations data will be collected over a two-year period to compare the performance of hybrid and standard diesel buses. The transit agency, headquartered in Hartford, Conn., began testing two hybrid buses and two standard buses on July 1. The four vehicles are all the same make and model, eliminating other factors that could affect the test results. The buses are 40-foot low-floor models manufactured by New Flyer with Allison transmissions. The hybrid vehicles use nickel metal hydride batteries with a life expectancy of six years. Hybrid buses will be put on regular routes in areas that involve slow speeds, stop-and-go driving and higher speed commuter express operations. Diesel buses will serve as a shadow to ensure data is comparable in distance traveled, temperature and road quality. CTTransit’s goal is to get accurate information about a hybrid vehicle’s fuel economy, brake life and emission levels to aid in future buying decisions. “We expect the hybrid buses to do better, but we want to know how much better,” said Stephen Warren, assistant general manager of maintenance. The hybrid buses showed superior fuel economy in the first month, even with significant idling times due to training. Emission levels will be tested in three segments, using identical fuel in both types of buses. The test will begin with the use of plain No.1 diesel, followed by operations with ultra-low sulfur fuel and with ultra-low sulfur fuel and a particulate filter. University of Connecticut students will test emissions levels. CTTransit received a Congestion Mitigation Air Quality grant and a capital grant to fund the project, estimated to cost nearly $1.5 million.