COLUMBUS, Ohio -- Officials have promised 3,000 new jobs, 1,500 new housing units and 300 new hotel rooms -- all as a result of a proposed downtown streetcar system.

While some city officials are in favor of the project, some transportation experts don't support the system, NBC 4's Colleen Marshall reported.

The streetcar system is thriving in Portland, Oregon -- and 40 other cities including Columbus are studying a return to downtown streetcars.

The new effort has critics focused after Central Ohioans have spent more than $13 million to study the feasibility of a light rail, bus rapid transit and streetcars in Columbus -- without a foot of track being laid.

"I just don't think that's plausible based on what we know about Columbus, as well as what's happened in other cities," said Sam Staley, of the Buckeye Institute.

Mayor Michael Coleman and his administration is predicting a six-to-one return on the $70 million construction price tag while The Buckeye Institute scoffs at the prediction.

The institute concedes that streetcars would enhance the quality of life for downtown neighbors.

"The real question is, 'Is this something that justifies the expenditure of public tax money in this?' And I don't think it does," Staley said.

Staley said that Columbus commuters are committed to cars and that streetcar proponents are ignoring the struggles of cities like Tampa, Fla., where ridership is far below expectations and costs are far above.

"We have to be very careful that we don't get overly optimistic on the benefits and underestimate cost of the project," said Bill Lhota, of Central Ohio Transit Authority.

Lhota is a member of the task force that is studying how to pay for a downtown streetcar system without a general tax increase.

The system could require steep subsidies and is not designed to ease congestion, but move people around the city's long downtown area.

"This is not broad based transportation solution at all. Rail only works in neighborhoods that are pretty dense," Staley said.

There are select neighborhoods -- including the Short North, Victorian, Italian and German villages -- that could benefit from a return to the old-fashioned streetcar.

But critics caution that all taxpayers could benefit from a return to fiscal restraint.

"I think streetcars have mixed results at best," Staley said.

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