Before I get into the details of each commute mode, I want to lay out the numbers. I'll mostly be presenting the costs in monthly terms and I wanted to show how I defined a 'month'. In a given year there are 365 days, excluding leap year. I don't work weekends so that removes 104 days of the year. Of the 261 days remaining, my employer observes 10 company holidays. From the 251 remaining days, I also subtract 20 vacation days, leaving 231 days. I get my share of colds and flu so it's fair to remove 6 more days where I don't commute to work. 225 days divided by 12 is 18.75. It is neater to deal with whole days for this discussion, so I'll round up to 19 days a month for travel to work. If I worked a .75 day, I'd still travel the whole way back and forth.

In addition to the number of days I travel, I have to lay out the distance I'd travel too. My ride to work by bicycle is a 35 mile round trip. I've chosen the route I take based on finding the best roads to bicycle that also link me with public transporation. The round trip by car is 25 miles. I could ride very nearly the same route on bike as I drive, but the car route involves a tunnel that is unplesant, noisy, dirty, and noisy. It's also noisy. The boarding points when taking public transportation are fixed so the distance traveled is less important when the destination is the same. So, it isn't fair to project the costs of driving based on the greater number of miles I travel by bicycle, and the result is that I'm working with a daily round trip of 25 miles, times 19 days for a montly total of 475 miles.

Using today's gas prices isn't fair for the past year, but show of hands, who expects gas prices will go down overall in the next year? Our one family car gets 20 mpg city/highway mixed which is the type of driving I would be doing to and from work. 475 divided by 20 is 23.75 gallons. 23.75 gallons at $3.30 a gallon is $78.38. I'll round that down to $78 dollars.

Maintenance: $113

Gas: $78

Total: $310

Maintenance: $16

Clothing: $12

Total: $35

To use public transportation, the most obvious option is for
me to walk a mile to BART, then walk a mile from BART to the Oakland
Alameda Ferry, then a mile from the ferry landing to work. I could
also use my bike for those walking links to save time and would
mostly likely do the latter. If I walked or rode to BART, then to
the Ferry then to work and reversed that at home, the daily cost for me is:

Ferry, round trip $3, BART round trip $3.70 a day. $6.70 X 19
is $127.30.

Monthy figures:

Riding: $35

Public Transportation: $127

Driving a car: $310*

(*purchased just to commute, and including maintenance costs, insurance, tags, etc)

I save about $275 a month cycling to work over buying a 2nd car. I save about $92 a month cycling over using public transportation. To show that with more impact, I save about $3300 a year by cycling instead of buying a 2nd car.

These costs are as exact as I can make them based on plowing through receipts, checking web sites, etc. I recognize these costs are not exhaustive, but I think they are a fair and reasonable approximation, and cover the largest ticket items, and express the low end of the equation. If you have specifics for costs of buying a new car to begin travel to work and back, send me details and I'll work that in as a hypothetical.

One thing that may be obvious, but can't be even closely approximated in cost terms is the difference in time spent in either of these modes. That discussion borders on the philosophical. However, it is still a worthwhile one for me to at least state my case. It takes me about an hour and 15 minutes each way by bicycle, about the same using public transportation, and it takes me about 25 minutes driving into work in the morning and 40 minutes to drive home. Here is the philosophical part. I get so tense, in a relative way, by negotiating the gridlock on the maze near the Bay Bridge and again near University Avenue, that I'd much rather spend the extra time riding. A human being needs exercise and I feel like I have saved the time of going to a gym or fitting all this exercise into my home life by riding to and from work. Besides, I really don't want to end up behaving like this.

In short, the real savings in bike commuting is to either not get, or get rid of a car. If you have a 2nd car that you leave at home, well, you are still paying for ownership, insurance, taxes and most of the maintenance.

The answer for me is pretty clear. Cost wise, it's far better for me to ride.

Comments welcome, no doubt I've forgotten something in my caluculations. If you have comments to make, corrections to point out or things to add, please send me mail at my rob dot hawks gmail dot com address.