Political leaders and financial experts emphasized job creation and the environment during a roundtable discussion Monday in Denver on transportation issues, but they noted that new projects face financial hurdles.

Proposals included improving freight and transit rail systems, connecting rural areas to services such as health care and investing in green construction jobs.

Minneapolis Mayor R. T. Rybak said efforts should include both new development and maintenance on existing infrastructure, in light of the Minnesota bridge collapse in August 2007 that killed 13 people.

“We have to play offense and defense at the same time,” Rybak said. “It should not be forgotten that [the bridge collapse] was not an act of God — it was a failure of man.”

In 2005, an American Society of Civil Engineers report estimated that $1.6 trillion in funding was needed over a five-year period to fix maintenance shortcomings such as the ones that caused the Minnesota bridge collapse.

While all agreed on the types of initiatives that are needed, panelists did not find consensus on funding sources. They all expressed the need for a private-public partnership, but the question of where to raise federal funding caused anxiety among the elected officials.

One key issue was that the current system for infrastructure funding, implemented in the Federal Aid Highway Act of 1956, relies on gas taxes for revenue. Rep. Rosa DeLauro (D-Conn.) called any attempt by Congress to raise the gas tax “dead on arrival.”

But Gov. Ed Rendell (D-Pa.) said that with or without the gas tax something had to be done to bridge the funding gap, noting that the $1.6 trillion cited by the ASCE report would only cover maintenance, not new projects.

“When I became governor I had to raise $2.4 billion in taxes,” Rendell said. “When re-election came around — people aren’t stupid — one incumbent lost and she voted against the tax increase.

“This is the time we have to challenge the American people. Folks, you get what you pay for.”

Terence M. O’Sullivan, general president of the Laborer’s International Union of North America, said new infrastructure projects could create hundreds of thousands of jobs.

O’Sullivan said unions such as LIUNA were capable of training new construction workers — but the challenge was finding them.