Seattle Transit Blog reports on a new study by the American Public Transportation Association (APTA) that ranks Seattle fourth in the nation in savings from taking transit instead of driving. (The top three cities were New York, Boston, and San Francisco). The report compares the monthly cost of taking transit---based on the average cost of a monthly transit pass---to the cost of driving, based on AAA's "average cost of driving" formula. That formula includes fixed costs like insurance, registration, depreciation, and finance charges, and variable costs like gas, maintenance, and tires, and assumes the average mileage for a midsize sedan and the average national price of gas.

STB notes that the rankings are based on somewhat simplistic data. For example,

the report doesn’t take into account ... the employer-paid fare subsidy for transit users or the parking subsidy for car users, both of which represent largely sunk costs that aren’t readily apparent each time a trip is made.  While I suspect that the differential would  vary considerably if those accommodations were made, that could only be assumed if mode use were mutually exclusive.  Since many transit users do own cars, it would be interesting to see how numbers would stack up if costs for both were factored together.

Nationwide, APTA calculates that people who switch from driving to riding public transportation save, on average, $816 dollars a month, or $9,797 a a year.