Transportation Secretary Brock Adams flew here in the Carter administration's first year and declared that Los Angeles sprawled hopelessly, and therefore could never have a federally financed subway system.

About a month before the California primary this year. Transportation Secretary Neil Goldschmidt climbed into a helicopter with Mayor Tom Bradley and flew over downtown Los Angeles' Wilshire Boulevard corridor. The day after the primary, Goldschmidt's Urban Mass Transporation Administration announced a $12 million planning grant for a subway under Wilshire Boulevard.

"We were very careful to make sure the announcement did not interfere with the political process," a senior federal official said.

This year, planning grants for new subway or trolley lines (which the transportation lexicon now calls "light rail systems") also have been awarded in Boston, Detroit, Honolulu and Portland. Houston may be next, because a decision has been promised there shortly after the Nov. 4 presidential election. Buffalo has a trolley system, mostly in tunnels, under construction.

New York City, northeastern New Jersey, Philadelphia, Cleveland, Washington, Chicago and San Francisco -- all with existing subway or elevated systems -- have received major grants for new construction or renovation. Miami and Baltimore have new systems under construction.

When it is added up, more than $1.5 billion in federal money has been committed this calendar year for subway or trolley projects around the country -- a remarkable turnaround in the administration's view of rail transit.

The last time the Department of Transportation (and Congress) had anything approaching this enthusiasm for rail was in 1976, when Transportation Secretary William T. Coleman Jr., campaigning hard for President Ford, handed out the grant for the new elevated railroad in Miami and promised Detroit $600 million for a subway (a promise that has yet to be kept).

Jack Gilstrap, executive vice president of the American Public Transit Association, had his tongue only partially in check when he said, "We move forward in four-year leaps.

"While election years tend to disrupt the bureaucratic process at times," he said, "there's something reassuring about knowing that the political process works. If that comes out as a grant in an election year, so be it."

Theodore C. Lutz, who was Department of Transportation budget chief under Coleman, general manager of the Washington Metro system, and is now Urban Mass Transportation administrator for Goldschmidt, agreed somewhat.

"The political process is real in the sense of timing," Lutz said. "But nobody has interfered with me on the question of merit on any of these projects. What [the election year] does do is create a sense within the White House that this is something we have got to deal with -- it creates pressure not to let the decision slide."

It would be too cynical to suggest that politics is the only reason rail systems have regained popularity. The past four years have seen demand for transit increase dramatically because of high gasoline prices and shortages, and new rail systems have enjoyed success.

When President Carter took office, the only major postwar rail system was San Francisco's Bay Area Rapid Transit (BART), and it was running poorly. Washington Metro had but five miles in operation, and its construction costs had been badly understated.

Carter dispatched a handwritten note to Secretary Adams that sent a shiver through rail transit advocates. "I suspect that many of the rapid transit systems are grossly overdesigned," the note said. "We should insist on (a) off-street parking, (b) one-way streets, (c) special bus lanes, (d) surface rail/bus as preferable alternatives to subways."

Adams asked Richard S. Page, his new transit administrator (and now the Washington Metro general manager), what could be done to bolster a rail transit program.

"I said we should lie low, hope that Washington Metro was successful and hope that Atlanta's subway opened on time and close to budget," Page said.

"That's not much of a strategy," Adams said.

"What else have we got?" Page asked.

Since then, Washington has opened an additional 32 miles of subway, and is undeniably a ridership success. BART is working better, and Atlanta's new subway opened on time and close to budget and is attracting more riders every day.

Gasoline prices have doubled.

One August day in 1979, Vice President Mondale appeared in Hoboken, N.J., and announced an administration initiative to devote $50 billion to transit over the next decade in hopes of increasing capacity by 50 percent.

"It must finally have occurred to the politicians over at the White House," one DOT official said, "that transit projects are built in big cities and that big cities have a lot of votes."

A constituency for transit also has been building in Congress, although it is difficult to say how it will be affected by the elections.

House Minority Leader John J. Rhodes (R-Ariz.), for example, said recently that if Republicans capture enough seats on Capitol Hill the money for major rail transit systems "just isn't going to be there." The Washington Metro, Rhodes said, is the last subway built with federal funds that he will support.

Republican presidential nominee Ronald Reagan has said little about transit or subways per se, but has suggested that states and localities be given more discretion in spending federal aid for transportation programs.

The money to satisfy everyone's ambitions will not be there, Urban Mass Transportation Administrator Lutz agreed, regardless of who wins the election. "But transit ought to put itself in the position the highway guys have been in for years," he said. "If some money shows up, there are engineering plans on the shelf that can be used to spend it."

Here in Los Angeles the process of developing those plans is under way. The $12 million grant that has been approved is only for detailed engineering studies, and the Wilshire subway easily could cost $2 billion. Lutz and others on his staff insist that an engineering grant does not mean that the federal government has agreed to build a subway. "Those days are over," he said.

What is proposed is a 16-mile system running west under Wilshire Boulevard, then north through the Santa Monica Mountains to North Hollywood. After years of bickering, Los Angeles County's 81 local governments got together to support that system, even though most of them would not benefit directly from it.

Because of Adams' statement that Los Angeles was too thinly developed to support a subway, planners generated data to show the Wilshire corridor comparing favorably in housing or employment density with successful rail lines in Philadelphia and Washington.

The subway is only part of an ambitious transit development plan for greater Los Angeles. The plan includes bus lanes on some freeways, a small downtown transit system on tracks called a people mover (a $36 million grant for which was handed out recently by Lutz), and an upgraded commuter rail program centered on downtown's Union Station.

The American Public Transit Association's Gilstrap ran the Los Angeles bus sytem until this year. "In the spring of 1979," he said, "events in the Middle East converted into a 36 percent increase in [Los Angeles] bus ridership within 48 hours. . . . Once you begin to ask how you're going to convert commuters from autos to transit most efficiently, you come up with rail."