I've griped before about "commute cost" calculations that ignore the value of a commuter's time; for example, last year, the Everett Herald concluded that taking the bus was the most expensive way to get from Everett to Seattle, a conclusion that's only possible if you assume that the value of a driver's time is zero. (The Herald also assumed that gas was the only expense involved in owning a car, but that's for another column).

Well, today, Seattle Transit Blog has done a similar exercise comparing the relative cost of driving across (untolled) I-90 or (tolled) 520, using the new app 520or90---but they, unlike the Herald , use the numbers (time and cost) to assign a value to the extra time drivers are willing to spend in their cars to avoid the 520 toll. In their example, taken at the peak tolling time of 4:02 pm, drivers who choose to take I-90 to avoid a $3.50 toll on 520 are valuing their time at $2.36 an hour---about a quarter of the state minimum wage.

One caveat: The app also assumes gas is the only expense associated with owning and driving a car. And it doesn't include a transit option.

Crossing the bridge on a Metro or Sound Transit bus at rush hour still costs just $2.50---less than the toll, and you don't even have to keep your eyes on the road.