What's striking about the 2010 Urban Mobility Report, released to much fanfare by the Texas Transportation Institute and the Kirkland-based INRIX traffic data firm this week, is what didn't change.

People in the Seattle-Tacoma-Everett region drove 56 million miles, identical to 2009 and similar to levels throughout the '00s. We remained the No. 14 metro area in population and ranked No. 12 in yearly traffic delay, compared with No. 11 the year before. Commuter driving took 27 percent longer than going the speed limit. Seattle drivers wasted an average 44 hours a year in congestion, same as 2009 but less than the peak of 52 hours in 1999.

With driving behavior pretty static -- some would say the road system around here is actually saturated -- a historical change may be underway, after tremendous growth in traffic during the latter 20th Century.

My own theory is that for the next quarter century or so, Seattle-area drivers will continue to fill our constricted highway network that grows slowly, if at all. The region would rely entirely on bus, carpools, rail, bikes and walking to accommodate growth in population. State research for the Highway 99 tunnel assumed 1 percent annual growth in driving, but even that trend could easily be canceled out by tolls, or if so-called "peak oil" leads to high prices at the pump. The plausible highway expansions near-term are carpool or tolled lanes, for instance at I-405.

Meanwhile, a closer look at the TTI numbers shows Seattle-Tacoma-Everett transit use up almost a third over the decade, from 145 million trips in 2000 to 160 million trips in 2005 and 187 million trips in 2010.

Gasoline use in Washington and Oregon has been flat, as heralded in this chart by the environmentalist Sightline Institute. And recent gas-tax predictions by the state Department of Transportation have downshifted to show a gradual decline. But diesel use by trucks is heading up, and Sound Transit's East Link light-rail extension is at least a decade away. Though Seattle environmentalists oppose multi-billion-dollar highway projects such as a six-lane Highway 520 bridge or a deep-bore Highway 99 tunnel, driving is hardly about to disappear.

In other fun with numbers, a federal Census Bureau survey shows bicycle commuting around 3.6 percent in the city of Seattle, close to what local advocates have conjectured. Portland ranks first at 6 percent, while Seattle, San Francisco, Minneapolis, Washington, D.C., and Tucson are over 3 percent, as shown in this chart at Seattle Bike Blog.

What do you think Seattle-area traffic will be like in 2025?