Miami — The downtown office worker looked up at the aluminum rail cars slipping by high over the Miami River on yet another test run of Metrorail, Dade County's new commuter rail system.
''Sure, I think I'll use it,'' he said as he paused for a quick breakfast before work. ''It's convenient to my home, and it's going to be a lot easier than fighting the traffic into town. It's going to be a great thing for Miami.''
For officials of the Metro-Dade Transportation Administration, that's just the kind of thinking they're counting on as they opened Sunday the first 11-mile leg of the 21-mile, $1 billion commuter rail system.
For the first time, Floridians were able to take a train to work yesterday, but the opening of Metrorail poses questions for not only Dade County but also for other fast-growing urban centers in Florida:
* Will Floridians get out of their cars to take a train to work?
* How will the rail system transform development in Dade County?
* Could a rail system work in other Florida urban areas to help concentrate their growth, which would help protect farm land and environmentally sensitive areas?
''A rail system should be part of any growth-management planning in Florida's larger cities,'' says John DeGrove, secretary of Florida's Department of Community Affairs and an authority on urban planning. ''It creates more compact urban development around the stations, and that helps solve environmental problems by protecting farm land, wetlands, and water recharge areas.''
Miami and Dade County have taken some innovative approaches toward creating a transit system, and some planners say the rest of the nation can learn a lot from these lessons.
The Metro-Dade Commission has drawn a boundary for urban growth that has helped curb sprawl and concentrated the population so that rail service is practical.
The commission also scrapped six new highway projects, which meant it was committing itself to rail transportation as the best way to move people.
And the transit administration has kept control of development rights immediately around the stations for the new Metrorail. It will be collecting a percentage of the income generated by the new businesses that will be built there, and that money will be used to help pay Metrorail's anticipated deficit, which could be 40 to 50 percent of its operating cost.
''I'm really high on that system; it's had good planning,'' Dr. DeGrove says. ''The state is going to grow, so we have to put all those new people on the ground in a much more imaginative way. Miami has shown us one way it can be done.''
Miami's system took nearly two decades to plan and build, and 70 percent of its cost came from the federal government, with 10 percent coming from the state and 20 percent from a local bond issue.
The genesis of Miami's rail system may not have been a traffic snarl, but a water shortage.
''In the mid 1960s, Miami had been planning to continually expand westward into the Everglades,'' says Fred Silverman, who had worked on some of the early Miami transit planning.
''But then in the mid-1960s came Miami's first water crisis, and Dade officials realized that the county could not continue to expand into its source of water, the Everglades,'' he explains. ''By the early 1970s, the county commission had come up with a new land-use plan that would drop a freeway system , compact the growth into a smaller area, and use mass transit as the county's spine.''
Ground was broken for Metrorail in June 1979, and during the next five years the forest of concrete piers grew south of downtown Miami along the corridor of an abandoned rail line to the city of Kendall and northeast to Hialeah.
Unlike most transit systems, Metrorail is not a subway. With Florida's porous limestone base and high water table, digging a subway would have been impractical.
Instead, the system is elevated on concrete piers, and the transit administration is taking the rough edge off the design by planting vines to grow up those piers, by making the stations architecturally interesting, and by incorporating artwork into the plans.
Much of the land under the elevated tracks has been turned into a park with a bicycle path running through it.
The electric-powered trains, each carrying two, four, or six aluminum cars with the blue and green Metrorail logo, glide along 161/2 feet over the streets and rise to 75 feet to make the passage over the Miami River.
Some Miami commuters wonder if the $1-a-ride fare won't dissuade people from taking the train, but Warren Higgens, the transit administration's director, says he believes people will find it a bargain.
''The fare is not too high when you relate it to parking,'' he says. ''It costs $6 a day to park in Miami, which makes it unattractive to bring a car into town.
''We've created a system where commuters can take a bus to the train station and the train into town for $1.25,'' Mr. Higgins says. ''That's $2.50 round trip , which is well below the cost of driving a car in.''
Metrorial will be focusing Dade County's growth right through the center of the county, rather than on the fringes where it would do more environmental damage.
''We now have a transit corridor, and we will have high-density construction around the stations,'' says Dade County Administrator Merritt Steirheim. ''From a planning standpoint, Dade is very sophisticated. We could take more farm land for development, but that would be counterproductive. We have land within the developed area that can have high density, and that's where we are directing our growth.''