Transit Ridership increases with Gas Prices

In what may be an irrational economic decision, people are getting out of their cars and on to the bus:

Soaring gasoline prices are pushing more commuters to use public transportation, say officials at L.A. County's two biggest rail and bus operators.

Ridership on the Red Line subway jumped nearly 12% in the first quarter of this year compared to the same period last year. Boardings increased about 8% on the Green Line and 3% on the Blue Line, said Marc Littman, spokesman for the Metropolitan Transportation Authority, which runs the rail services.

Ridership on the three lines rose along with gas prices this winter, increasing 9% each month from January through March. "It's a pretty big jump," Littman said. "We attribute it to the surge in gas prices."

Bus boardings also rose 9% each month over the quarter, an increase that Littman said was particularly dramatic in light of the season's rainy weather, which typically keeps riders away.

The cost of a round trip Metro fare is equivalent to a gallon of gas--$2.50. So at 20 miles per gallon, someone would have to be taking a Metro trip of 10 miles or more each way to justify the economic expense of riding public transportation... So when exactly does it make sense to take the bus?