The Carter administration today proposed a sweeping cutback in Amtrak. the nation's passenger rail network, except in the heavily traveled Washington-New York-Boston corridor.

Transportation Secretary Brock Adams said the administration wants to discontinue 16 inter-city passenger trains, restructure the routes of eight more and abandon about 12,000 of the 27,700 miles of passenger track. The proposal is broader than the Transportation Department envisioned last year.

Adams told a press conference in the center of Penn Station's ticket-selling area here that the streamlining of Amtrak would enable the government to trim about $1.4 billion from the $6 billion in subsidies it otherwise would have to give the rail service over the next five years.

He said the reduction would allow Amtrak to provide better service.

Although nearly 43 percent of passenger track would be abandoned, only 9 percent of Amtrak passengers would be affected, Adams said.

A number of major cities would lose all passenger service under the president's proposals, including Dallas, Atlanta and Omaha.

Trains operating out of Union Station in Washington tht would be dropped include daily service to Montreal, the Silver Meteor and Champion to Florida, the Cardinal to Cincinnati, the Hilltopper to Catlettsburg, Ky. and a growing commuter service to and from Martinsburg, W.Va., on the Blue Ridge.

DOT recommended that the Blue Ridge operate only on weekends for sightseeing trips to Harpers Ferry but said that if Maryland and West Virginia want to pay about $212,000 a year to subsidize commuters, the daily service could continue. The train carried 256,000 passengers last year.

The Southern Crescent from Washington to New Orleans also would be discontinued. (Details, Page D9.)

Congress has 90 days to reject the administration's proposal.If it goes along with the plan, Adams said, the reduced passenger rail network would go into effect Oct. 1. the start of fiscal 1980.

Reaction to the administration's proposals in Washington generally was restrained. Rep. James J. Florio (D-N.J.), newly installed chairman of the House transportation subcommittee, said the "general thrust of the program is one that few can argue with," because it emphasizes improved services in areas where riders use the trains. House Commerce Committee Chairman Harley O. Staggers (D-W.Va.), whose state would lose all passenger service, declined to comment until he has studied DOT's plan.

Florio promised hearings at "the earliest possible date" as did Sen. Russell Long (D-La.), Florio's counterpart in the Senate But the New Jersey Democrat also suggested as an alternative to congressional veto that Amtrak's system be reduced through the appropriations process -- mandating cutbacks by cutting funds rather than reacting to "immediate pressure" for a veto.

The National Railroad Passengers Association, which plans a nationwide campaign to win congressional vetoes, denounced the Adams plan. NARP assistant director Joseph Zucker said that "at a time of pending gasoline shortages," it makes no sense to cut out trains.

Spokesmen for Amtrak and railroad industry sources said congressional decisions probably won't be made until the reaction of constituents can be assessed. The only formal reaction from Amtrak was publication of an eight-page "perspective" paper, stating that the main issues "are not resolved initially by a map... but by deciding the key policy issues relating to the benefits and costs of a rail passenger system in context with the nation's total transportation needs."

While passenger rail service would be cut back throughout much of the nation, Adams said the administration envisions adding more service to the Washington-Boston corridor after a massive refurbishing of trains, tracks and stations.

He said Carter will ask Congress to add $654 million to the $1.75 billion it has already allocated to upgrade rail service in the Northeast corridor.

Adams said that all the lines between Washington and New York will be electrified.

When Congress appropriated $1.75 billion to upgrade the Northeast rail corridor, it mandated completion by 1981. Adams said that when the administration asks for an additional $654 million it also will ask Congress to extend the completion date to 1983 so that service will not be disrupted while tracks are being repaired.

The transportation secretary arrived for his press conference on an electric Metroliner from Washington, one of the trains that would be preserved under his proposal. The Metroliner carrying Adams and his entourage arrived seven minutes early.

As previously reported, the administration also will ask Congress to permit more rail mergers and route swaps among carriers to enable to freight-hauling rail business to revitalize itself. Carter also will request a gradual phaseout of the Interstate Commerce Commission's authority over freight rates.

Railroads operate about 194,000 miles of freight track, but haul two-thirds of the freight over just 40,000 miles of the track.

The freight lines were developed in the 1800s and early 1900s, Adams said, before there were trucks and airlines to carry inter-city freight.