Lessons from DART’s Electric Bus Pilot Program

As part of an ongoing commitment to operate as efficiently as possible, DART became the first public transit agency in Iowa to unveil electric buses in October 2020. By testing electric buses through a pilot program, we aimed to better understand whether using electric vehicles would lower costs for bus operations, maintenance and repairs.

Using mostly grant funding from the Federal Transit Authority (FTA) with a local match provided by MidAmerican Energy, DART purchased seven electric buses in 2020 from Proterra, one of the top electric bus manufacturers in the United States and began running the electric buses on Local Route 60 – University/Ingersoll in January 2021.

DART operated the electric buses for about 18 months before staff made a difficult decision to remove all seven from service just prior to when their major manufacturer warranties expired. Numerous issues had developed in the buses’ short lifespan, including problems with suspension, wheelchair ramps, weatherproofing and doors. Proterra technicians visited DART frequently during the pilot program to try to address the problems, but they were never fully resolved, making the buses unsafe and costly to run. 

“In a nutshell, it wasn’t a technology problem,” said DART Fleet Manager Keith Welch. “The chargers and batteries worked as designed. It was a bus build design problem that comes back to manufacturing.”

The Federal Transit Administration requires bus manufacturers to complete something called Altoona testing before buses can be sold. This process usually prevents situations like this from occurring. Pulling buses from service is highly unusual, and isn’t something DART has experienced before, but DART staff felt strongly that operating the electric buses was unsafe and chose to park them indefinitely. 

“Safety-wise, I can’t put them on the road,” said Welch. “To pull a two-year bus off the road and never run it again – that's unheard of... but they’re unsafe to run. I have purchased dozens and dozens of buses over the last decade or so and this has never been an issue. Every other bus DART has purchased has been able to meet and, in many cases, exceed its useful life.”

Lessons Learned

Despite removing the electric buses from service in fall 2022, DART learned several important things through the pilot program:

• DART’s seven electric buses reduced energy costs. During the pilot program, DART spent an average of $0.26 on fuel per mile for its standard diesel buses, while the cost for the electric buses averaged around $0.21 per mile, a 20% savings in energy costs. 
   
• DART’s seven electric buses emitted 60% less CO2 than diesel buses. A standard 40-foot diesel bus emits roughly 4.5 pounds of carbon dioxide (CO2) per mile, while the electric buses only released about 1.8 pounds of CO2 per mile.
   
• The battery technology on DART’s seven electric buses performed well in ideal weather but required more attention in extreme weather conditions. During stretches of temperate spring, summer and fall weather, DART’s electric buses ran more than 200 miles before a battery recharge was needed. When Des Moines experienced heavy snowfall and bitter cold temperatures, that range dropped to around 75 miles, as the extreme weather caused more strain on the batteries.

“With electric buses, the energy use is not from actually driving down the road,” DART Fleet Manager Keith Welch said. “It’s the energy to heat and cool the batteries.”

What's Next?

After the electric buses were removed from service, DART worked with Proterra to come up with a possible resolution. Just before reaching an agreement, Proterra filed for bankruptcy in summer 2023 and Phoenix Motor acquired the business. 

DART isn’t the only public transit agency facing this challenge. DART met with officials from the Federal Transit Administration (FTA) and with Phoenix Motor to identify a path forward for the electric bus pilot program. It was determined in late 2024 that DART could dispose of the buses by selling or donating the parts to other agencies without having to repay the federal government for the portion of funding DART used to purchase the buses.

Electric bus technology is still relatively new and requires time to fully scale and manufacture. As manufacturers continue building electric buses, they make improvements with each new model. DART’s Fleet Manager, Keith Welch, had the opportunity to test newer electric buses in January 2024, during a week with two major snowstorms and subzero low temperatures. He said, “they didn’t have any issues. We ran them for seven days straight in the cold and they didn’t have to come back in and charge throughout the day. The test bus returned with a minimum of 40% charge still left each day and was charged overnight.”

Moving forward, DART will continue to explore innovative solutions that can reduce operating costs, lower carbon emissions and improve how it provides public transit service.