Chicago’s Battery Electric Buses

Since October, the CTA has been operating two newly purchased battery electric buses. Since early December, I’ve gathered bus tracker data on the six routes that these buses are initially operating on: 7 – Harrison, 120 – Ogilvie/Streeterville Express, 121 Union Station/Streeterville Express, 124 – Navy Pier, 125 – Water Tower Express, and 157 – Streeterville/Taylor. I’ve also tracked some major north-south bus routes on the south side that I will comment on in a future post. As before, plots of the bus tracker data are available here. I’ve also added zipped csv files of the plotted position and speed data.

The electric buses, buses 700 and 701, have been replacing diesel buses on up to two peak-hour tripper runs per day each. Each run lasts between two and four hours and up to 35 miles. In the mornings, the buses have either taken run number 52 of route 157 inbound switching to route 121 at Union then the 120 in Streeterville, or they’ve taken run 54 of route 120, switching to route 121 in Streeterville, then route 124 for a round trip. In the afternoons, they’ve taken run 3 of routes 7, 125, and 121, or run 2 of route 7. On my plots of these routes, diesel buses are in red and electric buses in blue.

On the eve of US Thanksgiving, I had to occasion to ride bus 700 between Congress Plaza and Union Station.

The buses feel very similar to the trolley buses that I used to ride in Vancouver. Since their produced by the same manufacturer and have the same style body, many of the parts are likely shared.  The proven reliability of Vancouver’s large fleet of trolley buses bodes well for New Flyer’s foray into battery electric technology. Compared to a 40 foot diesel bus, these electric buses have much faster and smoother acceleration at low speed and much less noise. The majority of the noise from the bus seems to be coming from the flame of a diesel heater. The acceleration was also slightly greater than that of the Ben Franklin Transit’s battery electric bus I had ridden in Richland, Washington.

The increase acceleration reduces delays from stopping. This plot compares bus tracker positions of the 11 trips of the electric buses vs. 18 trips of diesel buses on run 2 of route 7.

7 - Harrison Diesel vs. Electric Bus Comparison

The electric buses seem to be significantly faster than the diesel buses.1)The very slow diesel bus was stuck in construction traffic on 8 January, 2015.

While the buses are only being initially tested on runs up to 35 miles long, they are designed to be capable of traveling between 80 and 120 miles between charges. This would allow the buses to operate on nearly all of the CTA’s peak hour trippers. However, in order to operate a 12-16 hours all-day base service trip, significant rescheduling, additional bus purchases, and increased labour costs, would be required. If the electric buses are successful, the CTA could convert around 40% of the fleet to electric buses for use at peak hour. This would require most of diesel buses to operate on exclusively 16-hour shifts. Diesel buses are currently rotated onto lighter duty peak hour service as they age.  This reduces the amount of canceled service and gap in service when buses break down and  stretches the life of buses to meet the minimum 12 years (or 500,000 miles) required to obtain federal funding for bus purchases.

While battery electric buses have some limitations, their low noise, good performance, and lack of toxic emissions are well worth pursuing.  If we really like them, we can reinstall trolley buses in Chicago to operate frequent all-day electric bus routes, and use battery buses on peak routes and detours.

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1. The very slow diesel bus was stuck in construction traffic on 8 January, 2015.

About fbfree

I am a graduate student in Physics at the University of Chicago.
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  • Steven Vance

    Have bus manufacturers rated electric buses as having a longer lifespan (assuming proper manufacturer-recommended maintenance is conducted)?

    • Fbfree

      I’m not sure about the life of the battery, but electric trolley buses generally stay on the road for 20-30 years with their original motors and transmissions. This is compared to 12-20 years for diesel buses*. While the batteries are expensive, they’re fairly easy to replace.

      * Toronto had doubled the service life of some ‘New Look’ buses by completely reconstructing them mid-life and replacing the engines and half the components.