Developing the World’s First Series Hydraulic Hybrid Bus: A Case Study

• Actuators - Hydraulic Actuators
• Infrastructure as a Service (IaaS) - Hybrid Cloud

• Automotive
• Transportation

• Product Research & Development

• Public Transportation Management
• Vehicle Performance Monitoring

• System Integration

The Federal Transit Administration (FTA) has mandated modern transit bus systems to provide more efficient services across America. Currently, U.S. public bus transit authorities are heavily subsidized to meet operating budgets, with State and local subsidies exceeding $19 billion per year and Federal subsidies exceeding $7 billion per year. The challenge was to design and manufacture a new bus with improved fuel economy, lower emissions, and a lower life cycle cost than the existing buses. The goal of the BUSolutions project was to meet these requirements and provide a sustainable solution for the future of public transit.

The customer in this case study is the Federal Transit Administration (FTA) and the U.S. public bus transit authorities. These authorities are responsible for providing efficient and reliable public transportation services across America. They are heavily subsidized by both state and federal governments to meet their operating budgets. The FTA has mandated these authorities to improve the efficiency of their services, reduce emissions, and lower the life cycle cost of their buses. The BUSolutions project was initiated to meet these requirements and provide a sustainable solution for the future of public transit.

BUSolutions, a collaborative effort between government and industry, was initiated to demonstrate the feasibility of producing easily maintainable, efficient city transit buses. Altair ProductDesign, the project leader, partnered with Automation Alley of SE Michigan and implemented a simulation-driven design approach. They made extensive use of optimization technologies and methods to drive a lightweight, fuel-efficient vehicle. 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, a series hydraulic hybrid system was chosen 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. This hydraulic system results in vehicles which are significantly more fuel efficient but still able to operate without updating transit authorities’ existing infrastructure.

• The BUSolutions project resulted in the world's first series hydraulic hybrid bus. The bus, with its optimized aluminum frame and hydraulic hybrid propulsion system, low friction tires, and lightweight interior fittings, offers a significant improvement in fuel efficiency. It is not only more fuel-efficient than conventional diesel buses but also more efficient than other diesel-electic buses available today. Moreover, the bus can operate without the need for updating transit authorities' existing infrastructure. This, combined with the lowest life cycle cost of any hybrid or diesel bus, makes it a sustainable solution for the future of public transit.

• The new bus design has twice the fuel efficiency of conventional diesel buses.
• The bus is 30% more fuel efficient than other diesel-electric buses available today.
• The bus is projected to save $25,000 per year per vehicle for transit authorities using the platform.