Developing the World’s First Series Hydraulic Hybrid Bus

The Federal Transit Administration (FTA) requires modern transit bus systems to provide more efficient services across America. Currently, U.S. public bus transit authorities are subsidized to meet operating budgets with State and local subsidies exceeding $19 billion per year and Federal subsidies exceed $7 billion per year. The goal of the BUSolutions project is to design and manufacturer a new bus with improved fuel economy, lower emissions and a lower life cycle cost than today’s buses.

Find out more about this project at

BUSolutions is a collaborative effort between government and industry, intended to demonstrate the feasibility of producing easily maintainable, efficient city transit buses. As leaders of the project, Altair ProductDesign partnered with Automation Alley of SE Michigan and implemented a simulation-driven design approach, making extensive use of optimization technologies and methods to drive a lightweight, fuel efficient vehicle. For example, the bus’ aluminum frame was designed using a series of optimization studies which helped to define the ideal material layout based on predefined loads and known manufacturing constraints.

For propulsion, Altair ProductDesign chose a series hydraulic hybrid system which converts stored hydraulic pressure into energy to drive the bus via hydraulic motors. Braking energy is captured and converted to pressurized fluid which is then re-used to provide acceleration. The hydraulic system results in vehicles which are significantly more fuel efficient but still able to operate without updating transit authorities’ existing infrastructure. Altair ProductDesign was responsible for the concept design, engineering, test and prototype build of the vehicle.

By utilizing a wide range of design innovations from the optimized aluminum frame and hydraulic hybrid propulsion system to low friction tires and lightweight interior fittings, resulted in a platform with twice the fuel efficiency of conventional diesel buses and 30% more fuel efficiency than other diesel-electric buses available today. This, combined with the lowest life cycle cost of any hybrid or diesel bus, is projected to save $25,000 per year per vehicle for transit authorities using the platform.

Be the first to know

Subscribe to our newsletter to learn about product training, news, events, and more!