The Federal Railroad Administration released Thursday the public's input on its Northeast Corridor Futures proposals, a set of potential improvements and redesigns for Amtrak's route from Boston to Washington.

Of 3,200 comments, 188 came from people in Pennsylvania, New Jersey, and Delaware. Those comments included enthusiasm for an Amtrak stop at Philadelphia International Airport, better connections between Amtrak and Regional Rail services, and a request for faster rail service between Philadelphia and Harrisburg.

The Futures program offered four options for the Northeast Corridor. The most radical ideas include a new Amtrak stop at the airport, a new station in Center City at the present Jefferson Station, and a tunnel that runs through the heart of the city to reach the new station.

When it comes to transportation planning, money is always a limiting factor and these ambitious options would cost money. Simply maintaining the existing rail configuration would cost $20 billion over 25 years, bringing the rail line to a state of good repair would cost about $65 billion, while the most ambitious plans, which would radically reshape the corridor, would cost about $290 billion.

The plan for an Amtrak connector to the airport drew a number of comments.

"I believe a direct 'pass through' connection to Philadelphia International Airport is critical as an enhancement to the NEC," one person wrote. "Taking a train is highly preferable to dealing with driving, parking, and shuttles to and from the terminal."

Another person wanted the FRA to prioritize a rail connection between Philadelphia's airport and Joseph R. Biden Jr. Amtrak Station in Wilmington.

Though Philadelphia and Pittsburgh are only about five hours away by car, a train ride is more like 71/2 hours. That's something that needs to change, another person said.

Providing high-speed service between the state's biggest cities is difficult, officials have said, due to the winding path of the rails that makes it difficult to reach top speeds.

SEPTA provides access to Amtrak through a stop at 30th Street Station, though the subway stop there is almost a block away from the iconic train station. One commenter asked that the FRA encourage more connections among area rail services, and more frequent service.

Clarena Tolson, Philadelphia's deputy managing director for transportation and infrastructure, wrote a letter to the FRA with questions about some of the options, seeking details about the possibility of clearing up a bottleneck area on SEPTA's Airport Line, track realignments proposed north and south of 30th Street Station, and further details on where a Center City station might be located.

The FRA will take the public's input and questions from government agencies to create a blueprint for the corridor's direction through 2040 that should be released late this year.

While it's the big changes that might grab people's attention, it's more small-scale improvements, like resolving SEPTA's bottlenecks, that can be more immediately valuable, said experts from the Delaware Valley Regional Planning Commission.

"I think in terms of our long-range plans and the way we think about transit generally we're still in a fix-it mode," said Greg Krykewycz, the planning commission's associate director for transportation.

The Futures plan addresses improving rail service near New York City and repairing tunnels in Baltimore - work that can affect convenience and reliability in Philadelphia.

"Just because the improvement isn't geographically located in our region doesn't mean our economy won't see a big boost," said Chris Puchalsky, the planning commission's deputy director for transportation planning.