Even if the Washington region completes all its planned transportation projects, such as the Silver Line and the Purple Line, traffic in 2040 will be just as bad as it is now -- and in many places worse.

That's according to a new analysis from the Metropolitan Washington Council of Governments, released Wednesday, that shows the region's economic and population growth will outpace all current plans for transportation improvement, even if regional leaders push through projects struggling to get funding like the light rail Purple Line from Bethesda to New Carrollton in Maryland.

"This is our best estimate as to what is there for the future. There's nothing that says this is inevitable, but it's a starting point for changing the future and having a different future," transportation expert Ron Kirby said at a meeting of MWCOG's Transportation Planning Board. "There is new capacity being built, but it's not sufficient to keep up with demand. There's not a lot of capacity going where all of the growth is going, which is in the outer jurisdictions," he said.

The growth will bottle up highways like the Beltway and the George Washington Memorial Parkway and stuff Metrorail cars: By 2040, rail cars on the Orange, Silver, Yellow and Green lines will be "highly congested" in the morning rush hour, carrying more than 120 people per car, unless Metro gets funding for more rail cars.

Arlington County Board member Chris Zimmerman disagreed with the conclusions of the study, saying he believed either states would eventually give more cash for transportation fixes or that the economic growth wouldn't happen.

"I don't think this is inevitable. I think the fundamental forecast there is untenable. You can't have both things," he said.

But officials agreed on one thing: that something needs to be done about traffic congestion and its resulting pollution, economic woes and drag on quality of life.

Transportation board chairman Todd Turner suggested the group should send a letter to Maryland and Virginia's general assemblies to urge them to find more funding for transportation and adjust land use policies. Both states are strapped for cash and earlier this year failed to find major new funding sources for roads. Most of Virginia Gov. Bob McDonnell's transportation plan was abandoned by state legislators in the spring, and Maryland lawmakers also failed to pass any major transportation funding, despite a report from a Blue Ribbon Commission outlining the state's road woes.

"For arterial and local roads, you've got to go back to traditional funding sources that haven't been increased: the gas tax, other user fees, vehicle registration fees," Kirby said. "Both governors in Maryland and Virginia are talking about addressing those in these next sessions. That's really critical, because that's where funding comes from for those expansions and maintenance."