This is one in a series of articles on President Reagan's fiscal 1986 budget proposals.

President Reagan's fiscal 1986 budget for the Transportation Department would eliminate subsidies for Amtrak's nationwide passenger railroad and for scheduled airline service to about 100 small communities and would severely cut federal aid to local transit systems.

The rest of the transportation budget -- including highway, aviation and transportation safety programs -- would be essentially frozen at fiscal 1985 levels.

The budget also includes another of the Reagan administration's oft-tried but largely unsuccessful attempts to charge user fees for many Coast Guard services.

The proposed elimination of Amtrak would save the administration $684 million over 1985 spending levels.

Amtrak officials claim that it also would result in the death Oct. 1 of all 250 Amtrak trains, that its 500 stations would have to be closed and that 25,000 employes would be laid off. That would cost the federal government $2.1 billion in employe buyouts.

Amtrak collects about 58 percent of its budget from revenues, primarily fares; the rest is from the federal subsidy.

Budget authority for urban transit programs would drop from $4.1 billion in fiscal 1985 to $1.4 billion in fiscal 1986. In essence, all transit aid would be eliminated except that made available by the 1-cent-per-gallon federal gasoline tax dedicated to transit.

There would be no federal aid for operating expenses and no federal discretionary grants, which could cause many smaller urban transit systems to close. The transit portion of the gasoline tax would be distributed by legislative formula.

The federal program subsidizing scheduled air service to small communities such as Dodge City, Kan., has been shrinking steadily and had been supposed to end in 1988 anyway. The administration would eliminate it three years before that.

The program, however, has strong political support in the Midwest and Alaska, where many small towns, far removed from major airports, do not have enough regular passengers to attract airlines.

The total transportation budget in the current fiscal year receives about 70 percent of its money from such user fees as taxes on gasoline, diesel fuel and airline tickets.

The administration estimates that user-fee financed transportation services will jump to 85 percent in fiscal 1986, largely through elimination of services not supported by earmarked taxes. Some legislative changes in the aviation trust fund also would be required for that goal to be met.

The budget protects continued financing for the new air-traffic-control computer system the Federal Aviation Administration is building.

The budget also reflects continued administration interest in contracting out services now provided by the federal government. And it promises an FAA assessment of whether the private sector can provide better weather and flight information to small-plane pilots than does the FAA.

Total proposed DOT budget authority for fiscal 1986 is $25.5 billion, about $4 billion less than in fiscal 1985.