A proposal to bring a high-speed maglev train system to the Washington region, which proponents say is key to addressing congestion along the Interstate 95 corridor, has reached a critical milestone.

The Federal Railroad Administration on Friday released a preliminary review of the project, laying out potential routes, as well as economic and environmental impacts of the train service that would move passengers between the nation’s capital and Baltimore in 15 minutes.

The 40-mile “superconducting magnetic levitation train system,” commonly called maglev, is planned as the first leg of a system that would carry passengers between Washington and New York in an hour. If federal approval is granted, which could happen as early as this year, the system could be built within a decade.

The project would cost between $13.8 billion and $16.8 billion, depending on the alignment chosen, according to the FRA report. That cost range is higher than previous estimates. Northeast Maglev, the private investors behind the project, had pegged costs at $10 billion to $12 billion. The group has said it secured $5 billion from Japan.

The federal agency analysis singled out the Baltimore-Washington corridor as ideal for such a project, citing its congestion levels, projected population growth and economic power. The existing transit connecting the two cities — Amtrak’s rail service, MARC commuter trains, and buses — suffers from reliability problems because of aging infrastructure and a saturated rail and highway system, the agency said.

“As demand on the existing roadway, transit and rail networks continues to increase, the levels of service of systems that operate near, or above capacity also continue to worsen,” the report says.

Despite robust opposition from residents, civic associations and elected officials in the project’s path, and after more than a year of delays, the FRA is nearing completion of the federal review that could lead to tunneling. The maglev could begin operating as early as 2030, the report says.

Wayne Rogers, the chief executive of Northeast Maglev, called the release of the draft environmental impact statement a “critical milestone in our effort to bring the world’s fastest train” to the region.

The technology that would be used, which has been tested in Japan, harnesses powerful magnetic forces that lift and propel trains four inches above a U-shaped guideway at speeds up to 375 mph. The trains between D.C. and Baltimore would travel as fast as 311 mph.

Two potential routes are under consideration, both parallel to the Baltimore-Washington Parkway, and beneath the areas of Bladensburg, Greenbelt, Laurel and Linthicum. There are six construction alternatives for each of the two alignments — east and west of the B-W Parkway.

On the west side, the rail line would track along the edge of the parkway right of way and affect some residential properties.

On the east side of the highway, the route would encroach on federal lands, including the parkway, the National Security Agency at Fort Meade and NASA in Greenbelt. Northeast Maglev officials say this is their preferred option, with a station at Mount Vernon Square in Washington, at Baltimore-Washington International Marshall Airport and in the Cherry Hill neighborhood of Baltimore.

According to the report, the project would generate between 161,000 and 195,000 jobs during a seven-year construction period and yield between $8.8 billion and $10.6 billion of potential earnings for employees.

Once built, the maglev could support between 390 and 440 jobs annually, and between $24.3 million and $27.4 million of earnings for workers, according to the report, which also highlights benefits to property values near the proposed stations in D.C. and Baltimore.

But construction would not come without negative impact as some communities between the two cities bear the brunt of disruption associated with the construction. Businesses on the route’s path would be likely to suffer financial losses, and road disruptions would create significant commuter delays.

“Temporary negative construction impacts to business revenues in the affected areas may be significant, ranging from $18.5 million to $311.3 million,” according to the FRA report. “This decrease in business revenues is due to lane closures, traffic delays and limited accessibility that would reduce the number of people frequenting the area and supporting businesses.”

The cost for riding would be higher than on MARC or Amtrak. According to the federal analysis, the expected average fare would be $60 for a one-way trip, although it could vary between $27 and $80 per trip. Amtrak’s Acela, which makes the trip between Washington and Baltimore in 32 minutes, costs about $46 one-way. The hour-long ride aboard a MARC commuter train costs $8.

“Maglev is a project that will disproportionately benefit the wealthy,” Prince George’s County Council member Jolene Ivey said Thursday at a town hall meeting organized by grass-roots activists opposing the project.

Critics say the high-speed system would offer little benefit to communities outside Washington and Baltimore, since BWI would be the only other stop on the D.C.-Baltimore leg. However, emergency exits and ventilation stations would be needed in locations along the line, requiring drilling as deep as 150 feet.

Prince George’s County resident Daniel Yuan, whose home is near the possible maglev route, said he is concerned about potential vibration as well as the impact on his property and green areas along the project’s path.

“It’s basically a limousine service for lobbyists going down to Washington. It doesn’t serve anyone in this community,” he said. “This plan is to build a train that nobody could ride.”

The train would run underneath and in proximity to homes, schools and recreational facilities. A single tunnel of 43 feet in diameter would carry two guideways and would be built using a tunnel boring machine at 80 feet to 170 feet below the surface.

The maglev project, the FRA concluded, “supplements other planned and programmed projects and helps alleviate transportation concerns in the region.”

Friday’s draft report comes four years after the agency began a process that included several public meetings. The FRA is expected to issue a final recommendation this year after a comment period. The agency could give clearance for tunneling or rule against building the line.

State lawmakers in Annapolis are pushing legislation this year that aims to stop the project by prohibiting it from going into certain areas, and they aim to give county governments greater authority on whether the project can be built, Ivey said. The FRA has agreed to extend the public comment period from 45 to 90 days, officials announced Friday, giving residents until April 22 to provide feedback. Residents and community leaders are pushing for a 180-day comment period.

Ivey said she has numerous concerns about the project’s economic feasibility, its impact on private property and park land, and lack of benefit for the communities between Washington and Baltimore. Although proponents say it is a private investment, the use of public funding is possible, she said, noting that such money could instead be used to improve existing rail infrastructure.

In 2016, the FRA awarded $27.8 million to Maryland for preliminary engineering and environmental studies for the project. No federal funding has been appropriated for construction.

Japanese media have reported that the Japanese government has offered $5 billion of financial backing for the Maryland line, and that Central Japan Railway, the train operator, has said it will not charge any licensing fees for the technology. Northeast Maglev would have to raise the remainder from public and private sources, company officials said, while also seeking federal loans and grants.

Rogers said Northeast Maglev is digging into the federal review to ensure that concerns “are addressed in the best way possible for communities and the environment.”