[zymhan]

I work 4.5 miles from my apartment in Atlanta. I can either spend 40 minutes in traffic getting home every day, or I can spend an equivalent amount of time on a train, and the a bus ride or walking.

In a lot of cities, driving is not faster. It's just sometimes the only option.

[pasttense01]

So how frequently does the train run? If it runs every hour that means on average there is a half hour wait for the train--in addition to the 40 minutes for the trip. Conversely the car is instantly available.