Gov. Ed Rendell's proposed 2010-11 transportation budget counts on $470 million in revenue from tolling Interstate 80.

If the federal government refuses to authorize I-80 tolls, the impact could ripple through the entire state, slowing repairs to crumbling bridges and roads and forcing transit systems to slash service and raise fares.

For the Port Authority, loss of I-80 funding would translate into a $25 million hole in its 2010-11 operating budget, said authority CEO Steve Bland.

"It would be a devastating impact ... it's hard to imagine how we would resolve that big a deficit without an impact on fares and/or service," he said.

"It's a serious and sobering problem," said state Rep. Joseph Markosek, chairman of the House Transportation Committee.

Compounding the problem is continued uncertainty about federal funding, as Congress debates various proposals for extending a surface transportation law that expired in October and a possible second economic stimulus measure.

"Overall, the transportation funding picture is very murky," said Pennsylvania Department of Transportation spokesman Rich Kirkpatrick.

An application by PennDOT and the Pennsylvania Turnpike Commission to toll I-80 is pending with the Federal Highway Administration, which is expected to issue a decision soon.

The Legislature in 2007 approved Act 44 to ease a transportation funding crisis that included the nation's biggest backlog of structurally deficient bridges and deficit-choked transit agencies.

Act 44 envisioned two revenue streams, from increased tolls on the turnpike and new tolls on I-80. Under the plan, the state expects to allocate $410 million to its 36 public transit agencies and $512 million for roads and bridges in the next fiscal year.

Even with federal approval, I-80 tolls won't begin this year. But a go-ahead would allow the turnpike commission to borrow against anticipated future revenues.

Subtracting I-80 from the funding equation cuts the Act 44 transit allocation to $250 million and highways and bridges to $200 million.

Mr. Rendell called that scenario "a body blow for mass transit."

Is there a Plan B?

"There is no backup plan that I am aware of at this point," said Mr. Kirkpatrick.

Mr. Markosek said Act 44 was Plan B, enacted because the Legislature did not want to raise taxes or fees.

"If we're unable to do that, we're looking at the rest of the alphabet," he said.

Raising gasoline taxes or license or registration fees during an election year is unlikely, he said. But asking the state's highway, bridge and transit programs to bite the bullet is also out of the question.

"It's inconceivable. We have an aging, geriatric infrastructure system that we simply can't ignore," Mr. Markosek said.

Thanks to a $1 billion infusion of federal stimulus funds, the state was able to allocate about $2.8 billion to highways and bridges last year, Mr. Kirkpatrick said. That spending is expected to fall back to about $1.8 billion this year.

In Washington there is talk about a second stimulus bill but no consensus.

The House in December passed the Jobs for Main Street Act, which provided $27.5 billion for highways and $8.4 billion for transit -- amounts similar to those in last year's stimulus funding.

A bipartisan Senate jobs bill unveiled last week would bail out the ailing federal Highway Trust Fund but does not have a separate stimulus component for transportation.

That measure would effectively continue federal support of highway and transit programs at 2009 levels and extend the expired transportation law, called SAFETEA-LU, through Dec. 31, giving give Congress another year to figure out how to fund transportation programs over the long term.

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