Electric buses

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All-Electric Bus Fleet by


We’re electrifying our entire bus fleet

Public transit is the greenest form of motorized transportation. We’re making it even greener by buying new electric buses and building out our charging infrastructure to make our bus fleet all-electric by the year 2040.

What's new

“Charging Forward” our roadmap to bus electrification

Following a multi-year analysis, we’re excited to share with you our planning report that will serve as the first-ever roadmap for the full-electrification of our bus fleet, facilities and supporting infrastructure by the year 2040.

The study, “Charging Forward: CTA Bus Electrification Planning Report,” (appendix) summarizes the findings of key analyses and establishes a practical framework for us to advance towards full electrification—all while ensuring that equity, the environment and the communities we serve are at the forefront of this next big endeavor.

Among the strategic recommendations outlined in the study, are:

  • Which technologies to invest in;
  • Where to install charging infrastructure;
  • How to sequence the electrification of garages and routes;
  • How to ensure that the related facility upgrades are coordinated with other modernization needs to maximize cost effectiveness and overall system reliability; and
  • Outlining an achievable transition timeline for meeting the agency’s 2040 conversion goal.

With the completion of this study, we are now well-positioned to compete for funding, advocate for policies, and drive technology advances that will be essential to implement this plan.

600-Series all-electric buses

Our newest all-electric buses, the Proterra 600-Series, are running on the #66 Chicago route! We’ve monitored their successful performance and have authorized the production of additional electric buses, bringing us one step closer towards our goal of making Chicago one of the greenest cities in the world.

Roll-out of these buses along the #66 route is the first step in a larger plan to electrify all bus service along Chicago Avenue. Selection of the #66 route for all-electric bus service was based on an analysis of the air quality benefits that this service would provide in communities along the western portion of this route, where the prevalence of respiratory illnesses is among the highest in Chicago.

Roadmap to full bus fleet electrification

For nearly the last decade, we’ve been at the forefront of bus electrification. In 2014, we became the first large transit agency in the U.S. to put electric buses into revenue service, across all four seasons. After rigorous testing of this early-stage technology, we made one of the U.S. transit industry’s first commitments to converting to an all-electric bus fleet. And in 2018, we made what was then one of the largest purchases of electric buses of any U.S. transit agency.

In April 2019, the Chicago City Council passed a resolution committing to electrify our entire bus fleet by the year 2040. And in April 2021, we began in-service testing with passengers of the next generation of electric buses.

Conversion of one of the nation’s largest transit bus systems—with nearly 1,900 buses over 120 routes, and seven bus garages—is a huge undertaking. Purchasing the buses is only one part of the equation.

Meeting our 2040 conversion goal will require time and resources. The following are some of the areas we’re addressing as we work towards this goal:

Charging infrastructure

The installation of charging infrastructure must go hand-in-hand with the purchasing of electric buses –electric buses are unusable without chargers to fill their batteries. Chargers are required at garages and along bus routes, otherwise the buses simply won’t run. Many of our buses travel more than 100 miles a day along their routes, and typical e-buses currently available have an effective range of about 70 miles. The planning and design of charging infrastructure—along with the planning and scheduling of bus routes to factor in charging needs—is a critical step to ensure that electric buses can provide consistent, reliable service.

For charging locations at the bus garages and en-route locations, we’ll need upgrades to the power supply for these facilities. We’re already in discussions with ComEd around the planning, designs, and timelines for these upgrades. Fortunately, we have deep expertise and decades of experience in high-power infrastructure based on the operation of our electric rail system.

E-bus technology and manufacturer capacity

While great strides have been made over the past decade, e-bus and charger technologies are still evolving, and there are several aspects that have not been fully tested that could have significant implications for our overall strategy for deployment. For example, two main types of chargers are currently available, “fast-chargers” and “slow-chargers.”

Fast chargers have many advantages in terms of cost and operational flexibility, but further experience is needed to assess the degradation rate of batteries when repeatedly fast-charged and reliability when fast-charged buses are stored outdoors in cold climates.

Also, production capacity is a bottleneck. Even at current levels of demand, manufacturers are struggling to keep up. Some U.S. transit agencies have reported delivery delays in their e-bus orders.

Like peer transit agencies across the country, we are taking a deliberate approach and phasing in electric buses over time to ensure the technology is well-tested and that we have enough vehicles to meet our service standards.

Aging existing bus fleet

We currently have more than 1,200 diesel buses that are at or near the end of their useful life (typically 12-14 years for transit buses).

We simply cannot wait to replace these buses: They are already past their useful life and have an average of 584,000 miles on the odometer. Buses of this age that have accumulated such extensive mileage are subject to breakdowns and maintenance issues at a higher rate, causing overall system reliability issues. These older buses also have significantly lower fuel efficiency and higher emissions than new diesel buses.

If our older diesel buses were retired without replacement, we would need to cut service and/or depend on an increasingly aged diesel fleet, which would result in more polluting and more frequent breakdowns. This is why we must move forward with a prudent purchase of new diesel buses to ensure we can continue to provide safe, reliable service at current service levels.

While not as low-impact as all-electric models, these new diesel buses are much more fuel-efficient and environmentally friendly than the older buses they will replace: they emit 22% less CO2, 64% less NOx, and 91% less PM2.5 (particulate matter) on a per-mile basis. They will also provide better fuel efficiency and require less maintenance.

These new diesel buses will allow us to provide safe, reliable service at current service levels while we tackle the barriers to going all-electric described above. Consistent with our plan for full fleet electrification, the diesel buses bought in the next few years will be retired before the 2040 electrification goal date.


Why is it taking so long to convert to an all-electric fleet?

Converting to an all-electric fleet is more than just purchasing buses, we also need the charging infrastructure to support day-to-day operations. And with a fleet of nearly 1,900 buses, this is a complex process that requires planning, coordination, construction and additional funding. Following a multi-year analysis, our new “Charging Forward” report helps layout the roadmap of what needs to be done and when, to help ensure we meet our 2040 goal.

Why is CTA purchasing diesel buses?

It’s important to know that diesel buses were always part of our fleet conversion plans. Currently, 64% of the buses in our fleet are at the end of their useful life, which is 12-14 years old. Without this recent diesel bus purchase, we would have to cut service and/or rely on a severely aged diesel fleet that is less reliable and emits higher levels of harmful emissions. The diesel buses purchased in 2021 will be retired before the 2040 electrification goal date.

Is CTA avoiding purchasing eBuses due to their higher purchase price?

No. The purchase price of eBuses is not the primary barrier to immediate, large-scale deployment. We are aware of the significant operating savings potential from electric buses, and we hope to realize these savings as we continue to scale up our electric fleet. We need time and resources to help plan, design and coordinate with ComEd the installation of new power and charging infrastructure at our facilities and at key locations along select routes where we can construct rapid charging stations for buses serving our longer routes. 

Why continue operating diesel buses that only contribute to Chicago’s health-impacting air pollution?

Our buses are responsible for a very small portion of vehicle emissions and overall emissions throughout the City of Chicago.  Even on corridors with the most frequent bus routes, buses typically constitute less than 2% of all vehicles.

In September of 2021 there were around 465,000 bus rides per weekday. If you assume a third of those trips could have been made by foot, bike, or not made at all, that’s still more than 200,000 car trips per day kept off the roads by operation of CTA transit.

Buses purchased in 2021 will be more fuel efficient and meet latest EPA emissions guidance, emitting 22% less CO2; 64% less NOx; and 91% less PM2.5 (particulate matter) on a per-mile basis compared to the older buses they will replace.

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