Federal officials are considering such a plan -- to be developed in two years and implemented in phases -- as part of an effort to improve rail service between Washington, D.C., and Boston, officials announced Tuesday.
The Federal Railroad Administration started its Northeast Corridor Future program a year ago with more than 100 ideas, and has pared it down to 15 options, including the Long Island Sound crossing. The current list will be cut in half by the end of the year and a final plan chosen by 2015, administration officials said.
Extending long-distance passenger rail onto Long Island would give residents a one-seat train ride with no transfers to New England -- without having to go through the bottleneck of Penn Station in Manhattan, program manager Rebecca Reyes-Alicea said.
"It's providing for better mobility, economic development possibilities and opportunities, and really just more options for riders through the Northeast," Reyes-Alicea said. "Long Island is currently not served by intercity travel."
Administration officials said it's too early to discuss details, including the potential project cost or the location of a bridge or tunnel across Long Island Sound.
Among the possible train routes to cities in Connecticut and Massachusetts are "Suffolk-Hartford-Worcester" and "Nassau-Stamford-Danbury-Springfield," according to the agency's report released Tuesday.
The plan is not only environmentally and economically beneficial but also essential, said Desmond Ryan, executive director of the Association for a Better Long Island, a planning group.
"During 9/11, you couldn't get off this Island except by ferry," Ryan said. "You cannot afford to effectively strand 3 million people."
Reyes-Alicea said the project would look to use existing infrastructure, such as Long Island Rail Road tracks, where possible and take advantage of unused or abandoned rights of way.
But any plan would require building new infrastructure, she said.
It would be implemented in phases over 25 years, with some "short-term" investments likely, Reyes-Alicea said.
As the plan progresses, the administration will reach out to LIRR riders, and hold meetings on Long Island, she said.
Long-distance rail travel on Long Island would not disrupt the LIRR's commuter base, the agency said.
LIRR officials declined to comment Tuesday, saying they needed time to review the various proposals.
The overall approach to reducing rail travel times throughout the Northeast includes trains moving as fast as 220 mph.
Administration officials said such high speeds may not be appropriate on Long Island, but trains faster than the LIRR's typical 80-mph maximum are possible.
Rep. Tim Bishop (D-Southampton), a member of the House Transportation and Infrastructure Committee, said he supports "high-speed rail and its potential economic and environmental benefits."
"Future investment in rail infrastructure in the Northeast will be a vital component of economic growth and sustainability," Bishop said.