Increases in the time it takes to get to work have changed the behaviour of commuters. No, they’re not changing their driving habits; they’ve simply figured out better ways of using the time they spend in traffic:
Rather than carpool, drivers adapt to gridlock: analyst.
Drivers are getting more cozy in their fully equipped cars and
becoming accustomed to gridlock, which one traffic analyst said is
leading to the demise of carpooling."[You have] entertainment systems, you have language lessons, you
have cellphones," said Pravin Varaiya, an engineering professor at the
University of California at Berkeley. "It’s your little space and you
have some free time, if you can call it that."Varaiya said that when the first High Occupancy Vehicle (HOV)
carpooling lanes were introduced more than 30 years ago, drivers were
considerably resistant."There was a lot of protest — ‘Here’s an empty lane and we are all stuck,’" Varaiya said.
Instead of changing their travelling habits and arranging carpools
of three or more, drivers instead adjusted to gridlock, he noted.
Worthwhile Canadian Initiative 
And drivers also freak out in bouts of road rage when crossed … that is a behaviour change I could do without.
On RPE I posted an article by Anthony Downs from Brookings, who argues that traffic congestion is a sign of economic success, and once there it is almost impossible to eliminate, barring a major recession. Why? Because as incomes rise people want cars, and with cars the freedom to travel when and where they want.
http://progecon.wordpress.com/2007/03/09/can-traffic-congestion-be-cured/