Allegheny County Executive Dan Onorato is seeking $7 million in federal funding to begin development of a multibillion-dollar mass transit system linking Pittsburgh International Airport, Downtown, Oakland and several East End neighborhoods.

He also has asked for $10.5 million for final design of a commuter rail line from Arnold in Westmoreland County to the Strip District or Downtown.

Mr. Onorato made those and other funding requests in a letter Friday to U.S. Reps. Jason Altmire, D-McCandless, and Mike Doyle, D-Forest Hills.

Congress has begun work on a new multiyear surface transportation funding authorization bill to replace the one that expires Sept. 30.

Mr. Onorato is hoping to capitalize on that, and on an administration that has signaled its intention to increase federal investment in rail and mass transit projects.

"As you know, President Obama wants to transform the way we travel in America -- both between cities and within cities -- in order to reduce dependence on foreign oil, lower carbon emissions, foster new economic development and give travelers and commuters more choices," he said in his letter to the lawmakers.

In an interview, Mr. Onorato said it was too soon to attach a timetable to his plans, but said it was important to have a blueprint of the region's priorities in the hands of federal officials.

"There's been a sea change of philosophy in Washington. We now have an administration that says we're reinvesting in this country. The new administration has definitely changed the discussion from wishful thinking to having a partner willing to invest and fund these projects," he said.

A rail line to the airport could originate at the end of the Port Authority's North Shore Connector, currently under construction, cross the Ohio River at Brunots Island and serve Mc­Kees Rocks, Stowe, Coraopolis and Moon, including Robert Morris University, said Kevin Evanto, Mr. Onorato's spokesman.

The Downtown-to-Oakland line could originate at the existing First Avenue light-rail station and use the corridor occupied by the Eliza Furnace Trail to reach Oakland. Or it could begin at Penn Station and follow the Martin Luther King Jr. East Busway.

On either route, much of the right-of-way already is publicly owned, Mr. Onorato said.

He envisions the Downtown-to-Oakland line connecting to a circulator system -- possibly using technology similar to West Virginia University's Personal Rapid Transit system -- serving the Pittsburgh Technology Center, Oakland, Shadyside, Bloomfield, Lawrenceville and the South Side.

The estimated development cost of the rail segments and circulator is $3.5 billion. Mr. Onorato said he wants to explore public-private partnerships to help finance the project -- perhaps having a private investor design, build and operate the circulator line and control development rights along it.

"I'm very open-minded. We're putting everything on the table as far as funding these projects," he said.

The $7 million Mr. Onorato is seeking would be used for preliminary planning, selection of routes and modes, and exploration of public-private financing.

The commuter rail line, which has been discussed and studied for at least a decade, would operate along the Allegheny Valley Railroad, a little-used freight line. It would have four peak-period trips per day and serve six or seven stations.

Mr. Altmire secured $500,000 in 2007 for a feasibility study that is nearly completed, and he has called the project one of his top transportation priorities. It would give commuters an alternative to driving on congested Route 28.

Mr. Onorato asked the congressmen to earmark funds for seven other projects: $25 million to rebuild and widen Campbells Run Road from Baldwin Road to Route 60 in Robinson; $32 million to realign and widen Painters Run Road from Robb Hollow Road to Bower Hill Road in Upper St. Clair and Scott; $35 million to rehabilitate the Mansfield Bridge, which connects Dravosburg, Glassport and Mc­Keesport.

Also, $12 million for a flyover ramp crossing railroad tracks at the Carrie Furnace redevelopment site in Rankin and Swissvale; $4.5 million for road improvements near the Tech 21 office park in Marshall; $2.5 million for road construction near Tech One Business Park in Monroeville; and $7 million for traffic improvements at the Allegheny Ludlum steel plant in Brackenridge.

"I represent a district that has enormous transportation needs and I'm going to have to make difficult decisions," said Mr. Altmire, the only local congressman serving on the House Transportation and Infrastructure Committee, which is writing the funding authorization bill.

The bill will have a requirement that all projects have 80 percent of their funding secured, to discourage members from steering money to projects that have little chance of being built.

Mr. Altmire said it was possible that the rail projects, if not included in that bill, could be funded from other sources, noting that the Obama administration already has committed or proposed $13 billion for high-speed intercity rail projects.

"There is definitely a new priority placed on rail projects and we hope this will fit into that somewhere," he said.

In a statement released yesterday afternoon, Mr. Doyle said: "I have received a number of requests from different local sources, including Allegheny County Executive Onorato. I greatly appreciate this input, and I'm working with local community leaders to work out the best way to proceed on the upcoming transportation bill."