That will only become more so as new cultural facilities, including new homes for the Miami Art Museum and the Miami Science Museum, and mixed-use mega-developments like Swire’s Brickell CitiCentre, open downtown over the next few years, said Jim Murley, executive director of the South Florida Regional Planning Council.

Murley, long an advocate for expanded regional transit connections, said he’s encouraged at the broad menu of options being explored, noting that each successful mode will remove cars from downtown’s traffic-choked streets.

It’s also significant that private entrepreneurs are investing in alternative transportation, he said, cautioning that slowing gas-tax receipts could put a strain on government transit funding.

“We’re effectively experimenting with a suite of options to test what works work in the marketplace — and in our humid, sometimes rainy environment,’’ Murley said. “If they’re predictable, and they’re there when we need them, I’m confident they will find a place. And that will be great.’’

The available evidence suggests there’s plenty of pent-up demand for alternatives to fighting traffic and parking fees. Well more than 700,000 riders now travel every month on the long-established but once underused Metromover, and ridership is climbing, Miami-Dade transit figures show. The agency also projects that the MIA connection will add thousands of new monthly rides to the 25-year-old Metrorail system.

Conceived as a quickly achievable substitute for fixed-rail streetcars, the two new city trolley lines — one a loop running between the Jackson Memorial Hospital district and the new Miami Marlins ballpark, and the second running from the foot of the Rickenbacker Causeway to the Omni — carry a combined 1,500 riders on non-game days, with sharply higher use when the team plays at home.

The Brickell-Biscayne line, inaugurated last month, has exceeded early-ridership projections by a factor of three, prompting the city to announce an additional, once-a-month route from downtown to Wynwood and Midtown Miami for art walks, which take place on the second Saturday of every month, starting in July.

If it proves popular, that line will be run every Saturday, Sosa said. The city also plans to link the health-district and Brickell-Biscayne lines along 14th Street, and eventually extend service into surrounding neighborhoods.

“I love it,’’ Romero said of her trolley ride, her second. “I just relax. And it’s a wonderful sightseeing tour also.’’

Earlier in May, the city parking authority approved another potential groundbreaker: a car-share program run by Daimler’s Car2go subsidiary. As early as July, Car2go will make 250 two-seat Smart cars available for short jaunts. The city also plans a bike-share program similar to Miami Beach’s popular DecoBikes , which earlier this month saw its millionth rider in just over a year of operation, and has also put in a bid to run Miami’s system. Planners expect the heaviest usage for the car and bike programs to be in and around downtown.

Neither the bike-share nor the car-share program requires taxpayer money. Like the Beach bike-share, Miami’s would be supported by rental proceeds and ads on rental kiosks.