The findings were presented at San Francisco's Commonwealth Club, where former Transportation Secretary Norman Mineta served as the moderator.
Transportation policy makers and researchers keep sounding the alarm -- transportation funding has not kept up with transportation needs for a couple decades now, with dire consequences.
"I think it's an intolerable situation, but I don't see an immediate solution in the near future," Mineta said.
"We have deferred maintenance on so many of our highway and transit systems that many of them are literally underground, behind the scenes crumbling," Mineta Transportation Institute researcher Asha Weinstein Agrawal said.
Among the researchers was Agrawal with results of a new study showing people might be willing to pay more federal gas tax, 10 cents more, if the money is dedicated to transportation projects that protect the environment.
"Ideally as a planner or policy maker you want to figure out that ideal policy that achieves really good social objectives and also is supported by the public," she said.
The study showed that support for a 10 cent gas tax increase was only 23 percent, but when that increase was tied to reducing global warming, support rose to 42 percent.
The 18.4 cent per gallon federal gas tax has been in place since 1993, and Mineta tried for an increase during his tenure as transportation secretary.
"I had a two cent increase the first year, a three cent third year and a two cent increase the fifth year. And President Bush said 'Norm, I don't want tax increases, get them out of there. So I took them out," he said.
But a gas tax increase is not a magic bullet, because even if it goes up, use of petroleum fuels is going down. Tolls, public private funding, pay-for-use express lanes and local sales tax measures are other funding options.