Breathe Easy…Ride the Green Wave

In 2010 Wave Transit introduced two diesel-hybrid buses to its fleet. The thirty-five foot heavy duty buses were manufactured by Gillig Corp. of Hayward, California. The diesel-hybrid propulsion system is powered by the Alison Hybrid EP40. This technology features two-mode compound split parallel architecture with two paths – a pure mechanical path and pure electrical path – to achieve the highest energy efficiency. Prior to purchasing the hybrid vehicles, Wave Transit polled systems that used the technology in an effort to gauge fuel efficiency and other factors that contributed to the sustainability claims made by the manufacturer. Additionally a cost benefit analysis was undertaken to determine if the $190,000 premium for hybrid technology would be offset by fuel savings over the twelve year life of the vehicle.
Although the vehicles have not been in service long enough to fully gauge operational efficiency, the Authority plans to monitor fuel savings, claims of increased brake life and other maintenance costs to determine if diesel-hybrid technology should be the preferred propulsion system for future heavy duty bus purchases. This analysis will be critical as Wave Transit prepares to replace over 66% of its heavy duty bus fleet in 2015.
Additional resources detailing bus emissions are available from Transit Cooperative Research Program (TCRP) Synthesis 84 explores the role of transit agencies in reducing greenhouse gas (GHG) emissions and examines the current practice of a sample of transit agencies.