Fresno Area Express Zero-Emission Bus Transition

The City of Fresno faces the dual challenge of rapid population growth and escalating environmental concerns. These factors demand a transformative shift in public transportation to align with the community’s evolving needs and California’s aggressive sustainability goals. In alignment with California’s Innovative Clean Transit regulation, the City of Fresno is converting its entire bus fleet to 100% zero-emissions buses by 2040, marking a critical step toward achieving the state’s ambitious environmental targets.

The Fresno Area Express (FAX) aims to provide a one-to-one replacement for approximately 120 compressed natural gas (CNG)-fueled buses with a combination of battery electric buses and hydrogen fuel cell electric buses, but the existing maintenance facilities lacked the required hydrogen safety systems, advanced ventilation, and fire suppression capabilities essential for servicing these new technologies.

As the facilities building design and zero-emission mobility consultant, GFT designed a new hydrogen fuel detection system to enhance facility fire-life safety in adherence with the National Fire Protection Association (NFPA) 2 and CNG codes. Our team undertook a comprehensive approach that included:

• Conducting a detailed site assessment to identify safety and system upgrade needs.
• Developing accurate cost estimates for budgeting and planning.
• Designing an upgraded electrical distribution system to support new loads.
• Enhancing fire pump capabilities and upgrading the generator to handle additional demands.
• Assisting with plan checks and permitting to streamline project approvals.
• Providing construction support for replacing heating, ventilation, and air conditioning (HVAC) units, ensuring seamless integration with new systems.

The project involved replacing critical HVAC components, such as boilers, chillers, exhaust fans, and heating pumps, and integrating these with new hydrogen ventilation systems to ensure optimal safety and operational efficiency.

Our team developed new rooftop hydrogen ventilation exhaust air fans with calculated airflow. To comply with NFPA 2 regulations, the fans are at least 50 feet from outside air intakes and interlocked with the hydrogen detection system and the existing roll-up door motors. This hydrogen fuel detection system project includes fixed zone detectors, zone control panels, and a central control panel. The hydrogen gas controls are designed so that if any hydrogen gas fixed zone detector detects an adjustable level of hydrogen gas, alarms will sound, the zone exhaust fan will turn on, and all existing roll-up doors will open.

During design, our team identified fire pump flow, pressure, and performance issues, as well as building system capacity and safety challenges. To solve these challenges, we:

• Upgraded the fire suppression system to comply with NFPA 2.
• Redesigned an electric fire pump to meet the building sprinkler demand.
• Implemented a dedicated room for the fire pump, pressure-maintenance pump, and associated controllers.
• Added sprinklers in the repair garage.
• Included a new generator to support the additional emergency loads.

Due to the nature of a transit agency, buses provide reliable transportation services by following strict routes and timeframes. Our team coordinated multiple stakeholders and successfully maintained full facility operations during construction.

By overcoming the complex challenges of upgrading the fire suppression system and integrating cutting-edge hydrogen detection and ventilation systems, the City of Fresno has a foundation for successfully transitioning to a zero-emissions bus fleet, significantly advancing its sustainability objectives.