Greater Bridgeport Transit (GBT) Battery Electric Bus Implementation

Greater Bridgeport Transit (GBT) engaged Wendel for the planning design and construction management for the incorporation of electric buses into GBT’s fleet and improvements to the existing Cross Street maintenance facility to accommodate electric buses. GBT obtained an FTA Low or No Emission grant for the purchase of two battery electric buses and facility upgrades. The buses are expected to arrive at Greater Bridgeport in May of 2020. GBT anticipates an ultimate buildout of eleven battery electric buses.

Wendel’s scope of work included project initiation, concept design, schematic design and construction administration. Work included the planning and development of a smart charge electric bus system that was scalable and flexible to accommodate multiple electric bus manufacturers. Wendel analyzed the energy needs and worked with the local utility to determine rate structure, impact of rates on GBT’s operations, and impacts to the utility and GBT’s electrical distribution systems. Charging strategies, charger sizes and types, impacts on mechanical systems such as HVAC, bus maintenance lifts, and fire protection systems were included.

Current codes have not kept pace with the development of battery electric buses. Wendel, working with the local code officials, the State Fire Marshal and the insurance companies developed a fire protection system to protect the garage and surrounding buses from a lithium ion battery fire in an electric bus.

GBT ultimately chose Proterra as their supplier for the buses and the charging equipment. The initial design included charging for five electric buses utilizing Proterra 125 kW chargers. A new utility transformer was installed along with replacement of the main switchgear to accommodate the projected battery electric bus build out. Construction was completed on the main service feed and switchgear ahead of schedule in December of 2019 and the chargers were installed in April of 2020 ahead of the bus arrivals in May 2020.