MTA’s fleet of 5,800 buses is the largest in the country, accounting for 10% of all transit buses in the U.S. The fleet operates out of 28 bus depots as well as three central maintenance facilities located across New York City and Yonkers, N.Y.  -  Photo: MTA/Marc A. Hermann

MTA’s fleet of 5,800 buses is the largest in the country, accounting for 10% of all transit buses in the U.S. The fleet operates out of 28 bus depots as well as three central maintenance facilities located across New York City and Yonkers, N.Y.

Photo: MTA/Marc A. Hermann

The country’s transit agencies are preparing for the most sweeping and complex transformation of bus fleets in history.

The dramatic shift to achieve 100% zero-emission bus (ZEB) fleets will involve massive capital investments. Among the challenges, agencies must overhaul aging storage and maintenance facilities to accommodate new battery charging or hydrogen refueling infrastructure.

Major projects are already in the works. To illustrate the scale and variety of approaches, this article takes a closer look at ZEB programs underway at three of the country’s largest agencies: New York Metropolitan Transportation Authority (MTA), San Francisco Municipal Transportation Agency (SFMTA), and Washington Metropolitan Area Transit Authority (WMATA).

New York's MTA Takes Four-Stage Approach

New York’s 2019 Climate Leadership and Community Protection Act committed the state to reduce economy-wide greenhouse gas emissions 40% by 2030 and 85% by 2050. Ahead of the law’s passage, MTA announced plans to transition the agency’s entire bus fleet to ZEBs by 2040. All new bus deliveries will be ZEBs starting in 2029.

MTA’s fleet of 5,800 buses is the largest in the country, accounting for 10% of all transit buses in the U.S. The fleet operates out of 28 bus depots as well as three central maintenance facilities located across New York City and Yonkers, N.Y.

The transition requires careful consideration into the phasing plans for new charging infrastructure, power supplies, and depot modifications, aligning those projects with long-term ZEB procurement plans.

“We are focusing on in-depot charging, using high-capacity chargers. This requires new electricity generation, which we’re coordinating with [utility provider] Con Edison,” says Chief Officer, Zero-Emissions and Fleet Technologies, Sunil Nair. “We’re also exploring other options like on-site battery storage and solar power generation.”

MTA is upgrading facilities in four stages:

  • Stage 1 (2015-19 and 2020-24): 560 battery-electric buses (BEBs) deployed to test performance of charging infrastructure and to assess BEBs’ operational feasibility.
  • Stage 2 (2025-29): More than 1,000 ZEBs will operate across multiple depots.
  • Stage 3 (2030-34): About 60% of fleet will consist of ZEBs, likely a mix of BEBs and hydrogen fuel-cell electric buses (FCEBs).
  • Stage 4 (2035-39): All remaining combustion engine buses will be retired and replaced with ZEBs.

Throughout each phase, MTA will prioritize environmental justice, technology advancements, and workforce development.

“The transition will require changes in workforce knowledge and skills related to safety, bus maintenance, facility maintenance, and dispatch operations,” says Nair. “We’re developing training programs and making use of existing expertise to ensure that our workforce is empowered to take on these changes.”

SFMTA plans to replace the agency’s 566 diesel-hybrid buses within the 2040 target, provided the agency can overcome anticipated technology barriers and scale-up challenges.  -  Photo: SFMTA

SFMTA plans to replace the agency’s 566 diesel-hybrid buses within the 2040 target, provided the agency can overcome anticipated technology barriers and scale-up challenges.

Photo: SFMTA

SFMTA: Breaking it Down to Built it Up

California’s Innovative Clean Transit Regulation requires the state’s larger transit agencies complete a ZEB overhaul by 2040. All new purchases must be at least 50% ZEBs by 2026 and 100% by 2029.

SFMTA plans to replace the agency’s 566 diesel-hybrid buses within the 2040 target, provided the agency can overcome anticipated technology barriers and scale-up challenges. To accommodate the agency-wide transition to BEBs, infrastructure upgrades are planned for all six SFMTA bus facilities.

"It's a two-fold problem," says Bhavin Khatri, SFMTA's zero-emissions program manager. "Some facilities are over 100 years old. It doesn't make sense to install charging infrastructure and then, five years later, we may need to rebuild the entire facility."

“And we can’t just shut down a bus yard,” Khatri continues. “The consequence is that it takes longer — three to five years — to retrofit these facilities and perhaps six to 10 years for new construction.”

SFMTA’s rollout plan initially focused on addressing the functional obsolescence and life safety concerns of facilities already identified for renovations. SFMTA’s Building Progress Modernization Program targets a rebuild of the 4.4-acre Potrero Yard by 2027 and the 109-year-old Presidio Yard by 2029. 

In response to their 2029 ZEB goal, SFMTA is now advancing a new renovation project at Kirkland Yard as well.

The heavily congested Kirkland Yard facility houses an aging diesel-hybrid fleet, which SFMTA has identified as the first fleet scheduled to be entirely replaced with BEBs.

“Kirkland Yard presents an early opportunity to jumpstart 40-foot BEB facility capacity through a near-term electrical upgrade and site improvement,” explains Khatri.

Additional facilities upgrades are planned out in a series of phased improvements between 2026 and 2040. Islais Creek Motor Coach Facility and Flynn Depot are expected to require minimal additional capital investment, whereas Woods Yard will likely need to be fully rebuilt and expanded.

“SFMTA will continue to analyze the facility program and will engage the SFMTA board for advice and policy guidance on various potential approaches,” says Khatri.

WMATA’s board has committed to lower the agency’s carbon footprint and address regional environmental justice concerns by purchasing 100% ZEBs by 2027.  -  Photo: METRO Magazine

WMATA’s board has committed to lower the agency’s carbon footprint and address regional environmental justice concerns by purchasing 100% ZEBs by 2027.

Photo: METRO Magazine

WMATA Sourcing New Power

WMATA is a tri-jurisdictional agency established between Washington, D.C., Maryland, and Virginia. Due to its unique structure, WMATA must comply with climate policies across the metropolitan area. When planning which capital projects best address those policies, spending plans must prioritize equal allocation across the tri-jurisdictional area.  

WMATA’s board has committed to lower the agency’s carbon footprint and address regional environmental justice concerns by purchasing 100% ZEBs by 2027. Their longer-term goal is to convert the fleet of more than 1,500 buses entirely to ZEBs by 2042. Nine storage and maintenance facilities will require major renovations and power upgrades.  

Initial projects include the demolition and reconstruction of the circa-1906 Northern Bus Garage (150 BEBs), the 17.6-acre Bladensburg Bus Garage (150 BEBs), and heavily congested Western Bus Garage (120 BEBs). Beyond these projects, preparations are underway to convert Northern Virginia’s Cinder Bed Road Bus Division to accommodate 112 BEBs. 

Electrifying the fleet will require significant sources of new power. WMATA is coordinating with electric utilities that service the region, evaluating power infrastructure upgrades necessary at each depot and forecasting potential peak demand.

To ensure resilient supply of low-carbon power and cost-effective operations, WMATA is expecting to develop distributed energy resources that can offset power from each facility’s relevant utility.  

“We have to start conversations with each utility early in the planning process,” says WMATA’s sr. VP, bus transformation, Jeffrey Hiott. “To enhance resiliency, we are attempting to have dual feeds wherever possible, pulling from extra substations if available. That said, not every garage has that ability.”

While each project comes with design and construction challenges, Hiott notes that the program as a whole presents a mix of complications.

“WMATA foresees that the biggest challenges to meeting our ZEB goals will include aligning bus deliveries, infrastructure commissioning, and budget availability,” he says. “A robust transition plan gives us a really good roadmap. We anticipate we’ll need to face new challenges and learn from them every step of the way.”

Throughout each of its planned phases, MTA will prioritize environmental justice, technology advancements, and workforce development.  -  Photo: MTA/Marc A. Hermann

Throughout each of its planned phases, MTA will prioritize environmental justice, technology advancements, and workforce development.

Photo: MTA/Marc A. Hermann

ZEB Transitions Are Just Getting Started

Today, an estimated 5,500 BEBs or FCEBs have been sold across the country. That’s a 66% increase since 2021.

Yet, the transition is just getting started. Over the next two decades, a significant share of the country’s 50,000 transit buses will be replaced with ZEBs.

As agencies plan out their transition, the challenges that await will be unprecedented. Never before has any transit agency — or any fleet operator — undertaken such a tremendous shift in how their vehicles are operated, powered, maintained, and stored. Even ZEB manufacturers are unsure how this will play out.

The complexity and scale underscore why it is critically important to develop deliberate, engineered solutions with the support of design consultants who understand all that’s involved in the ZEB transition.

A total fleet overhaul requires bus facilities undergo significant reengineering — from major electrical infrastructure upgrades and structural enhancements to the design of state-of-the-art charging and communications networks. Many depots will need to be totally demolished and reconstructed.

For MTA, SFMTA and WMATA, how these agencies approach their programs will have impacts far beyond their service territories.

Bus system operators across the country are watching. With every achievement, their progress shows that the transition to ZEBs is no longer an exercise of imagination. The ZEB transformation is well underway.  

About the Author: John Drayton is Zero-Emission Mobility National Practice Lead at Burns Engineering.

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