RIPTA Electric Bus Charging Station and Facility Upgrades

The Rhode Island Public Transit Authority (RIPTA) provides public transportation to more than 40,000 Rhode Island commuters daily. Buses are their primary mode of transportation, with many facilities throughout the state to administer operations. These facilities require both routine maintenance and forward-thinking upgrades to ensure the best service for their customers.

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Challenge

At one of RIPTA’s bus maintenance facilities, 13 twin post bus lifts required replacement. The existing twin post lifts have deep pits in the concrete slab-on-grade that required significant modifications to accommodate the new lifts. Additionally, the existing drainage system at the bottom of the pits required significant modifications to connect the new, shallower, pits to the existing oil/water separator system as required by the State of Rhode Island Building Code.

In addition to maintaining operations, RIPTA has recently invested in the lease of three 40-foot Proterra Catalyst E2 electric buses to replace the aging diesel fleet. These electric buses require custom charging stations that provide a 60 kW charging unit, which is a significant load on existing buildings.

Collaboration

We worked with RIPTA to determine the optimal facilities for the electric buses and their charging stations. After the site selections were made, we assessed the existing electrical infrastructure at each and worked with National Grid (NGrid) to determine the optimal facility for the buses and chargers, as well as the existing electrical service impacts. We coordinated closely with the manufacturer and RIPTA to determine locations of equipment, day-to-day access for RIPTA personnel, and maintenance of the equipment.

Practice Areas Involved

Design

For the maintenance facility, we are replacing HVAC equipment, makeup air units, and exhaust fans. We are providing associated mechanical, electrical, plumbing, and structural design and associated upgrades to existing systems. We are preparing drawings for the modification of the sanitary system associated with the new bus lift upgrade and evaluating rooftop equipment replacements. We are providing construction administration services for this project, including construction monitoring.

For the charging stations, we designed the necessary electrical distribution system modifications to incorporate the Power Control Systems (PCS) and dispensers. We are currently working with RIPTA and NGrid to address additional buses and subsequent electrical load, including potentially incorporating solar PV at these facilities to offset the electrical load.

Impact

RIPTA will use what it learns from the leased electric buses to prepare for the purchase of 16 to 20 electric buses starting in 2021. When added to RIPTA’s existing hybrid diesel electric buses (which combine diesel with battery power), these all electric buses will give RIPTA a fleet that consists of approximately 36% and low- and zero-emission vehicles.