Electric buses

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.

New electric buses are now in service

Proterra all-electric bus
Proterra electric bus (April 2021)

Our newest all-electric buses 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 have been at the forefront of bus electrification. In 2014, we became the first large transit agency in the United States to put electric buses into revenue service, carrying customers 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 more than 1,800 buses over 120 routes, and seven bus garages—is a huge undertaking. Purchasing the buses is only one part of the equation. Meeting our goal will require progress on several fronts at once:

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 CTA 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 are able to provide consistent, reliable service.

E-bus technology and manufacturer capacity

While great strides have been made in e-bus technology 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 1,000 diesel buses purchased in 2006 that are at or near the end of their useful life (typically 12-14 years for transit buses), plus another 200 diesel buses that will reach the end of their useful life in 2022. We are replacing some of these old diesel buses with new, more efficient diesel buses.

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.

A new implementation study

To guide the sizable investment required to achieve full conversion, we will soon release an electric bus implementation study that will serve as a roadmap to guide bus replacement, charging infrastructure installation, garage facility upgrades, and electric bus operations and maintenance over the next 20 years. This study is evaluating different potential approaches and associated infrastructure needs, service and operations impacts, costs, and timelines associated with converting our fleet of more than 1,800 buses to all-electric. The study also includes analysis of where electric bus deployment can deliver the greatest benefits to communities most vulnerable to, and adversely affected by, the health impacts of vehicle emissions.