Have Spreadsheet, Will Travel

An engineer records — and reflects on — six months of commuting

Image copyright Rocky Mountain Institute, by Peter Bronski.

I’m an engineer, so it may not surprise you that I kept track of my daily commute in a spreadsheet, just for fun, for my first six months at RMI. I am fortunate to have several options for getting to work at RMI’s Boulder, CO, office, including bicycle, bus, and car. I’ve used them all, and I have a spreadsheet of data to prove it.

My favorite way to commute is by bicycle, about three and a half miles each way. My transition to biking was gradual. It started several years ago, while I was attending graduate school and driving about three miles each day to and from campus. I decided to try biking instead, initially once or twice per week. Soon, I was bike-commuting every day the weather was good, and then pretty much all the time throughout the spring, summer, and fall. Fast-forward to today. Each day, I decide how to get to and from work based on the weather, how I’m feeling that day, and what errands I need to run after work.

Saving cash, saving carbon, burning calories

In my first six months with RMI through February 2015, I made 214 one-way trips between home and RMI’s Boulder office — 47 percent by bicycle, 40 percent by public transit (bus), and the remaining 13 percent by car (either by driving or getting a ride in a car). But how did that compare to a baseline of driving to work every day?

Most people consider the “cost” of their commute in dollars, so let’s start there. First, I should admit that, for me, any option other than driving is free, although they are not free for others — RMI provides employees with an EcoPass for riding the bus, and any maintenance needed for my bicycle is done by my husband, formerly a bicycle mechanic. Because of recent fluctuations in gasoline prices, I analyzed three different price cases: low ($2 per gallon), medium ($2.75), and high ($3.50). Our car gets about 20 miles per gallon in Boulder’s city driving conditions.

Image copyright Rocky Mountain Institute, by Peter Bronski.

In these scenarios, each driving trip to or from work cost me somewhere between $0.40 and $0.70 in gasoline — not a huge amount — plus those modest miles’ contribution to maintenance costs and their share of fixed costs (registration and insurance). But by driving only 13 percent of the time over the six-month period, I spent $74–130 less than if I’d driven every trip. That might not sound like much over six months to some people, but that’s still enough cash to buy about 12.5 burritos at Chipotle. Those with longer commutes would save more.

Then there’s the environmental cost in carbon emissions. I assumed that my bicycle commute resulted in negligible CO2 emissions, 8.88 kg of CO2 emitted per gallon of gasoline for my car, and 0.107 kg of CO2 emitted per passenger-mile on the bus. Compared to the baseline of driving in both directions every day, my actual commuting habits over six months saved ~260 kg of CO2 emissions. I don’t actively think about emissions when I’m deciding how to get to work each day, but seeing how these avoided CO2 emissions added up really drove home the impact of my commuting choices.

Bicycle, bus, car — I’ve used them all,
and I have a spreadsheet of data to prove it.

Finally, there’s the health cost. I started with a baseline of about 50 calories burned for each trip while either driving or sitting on the bus. I walk about half a mile to the bus stop — for this I assumed burning an extra 50 calories. When I bike, I make the trip to work in about 25 minutes. According to an online calculator, biking at my moderate pace burns about 250 calories per trip. This resulted in 35,000 total calories burned by my mix of biking, riding the bus, and driving. When compared to driving to and from work every day, the difference is about 25,000 net calories burned. That’s the equivalent of about 30 Chipotle burritos!

So over six months, my commuting choices resulted in far more calories burned (30 burritos) than money saved (12.5 burritos). I found this pretty exciting, even without taking into account the additional health benefits of breathing fresh air and soaking up vitamin D from the sun, or the mental health benefits of biking, walking, and taking the bus, including avoiding the stress of negotiating car traffic and finding a place to park.

A larger mobility transformation

After looking at my own personal mobility transformation, I know that I am fortunate to live relatively close to my office in a bike-friendly community that also has a great bus system. This makes it easy for me to embrace multimodal commuting and choose the best way to get to work each day. I hope more communities around the country can move towards a similar mobility paradigm that makes it easier for many more commuters to make the transition that I have. Based on a quick look at my commuting experience over six months, it’s clear that our climate, our wallets, and our waistlines would all benefit.

Written by Kaitlyn Bunker, an associate at Rocky Mountain Institute.

Web Extra

For more information on this topic visit: rmi.org/transportation