NASHVILLE, Tenn. (AP) — A $5.2 billion proposal to build an extensive transit system in Tennessee's booming capital city would introduce light rail and carve out an underground tunnel downtown, Nashville Mayor Megan Barry announced Tuesday.

At a news conference, Barry unveiled details of her plan that would feature more than 25 miles (40 kilometers) of light rail, additional bus service and the tunnel. The ambitious project would hinge on a package of tax increases that the mayor wants to put before voters in May.

She said the new revenue would come from boosting the city's sales tax by a half-cent per dollar in 2018, followed by another half-cent hike in 2023. It would also increase taxes on hotel stays, rental cars and businesses. The tax increases would be effective until 2068.

Barry envisions the project being completed in phases by 2032. Bus system improvements would start in 2019 and the first light rail lines would open in 2026.

The mayor has touted increased transit options as a necessity to clear up congested roads in a city that grows by almost 100 residents a day. About 660,400 people lived there as of July 2016 population estimates.

"We are not going to pave our way out of traffic jams with wider roads, and we're not going to stop growth," Barry said at a news conference Tuesday. "But we can do something to manage growth, and we can make sure it benefits everyone."

The $936 million downtown tunnel would stretch for nearly two miles (3.2 kilometers) as a connector with three stops for trains and rapid buses. A new station would be built along the entertainment district's strip of honky-tonk bars.

Barry said she shares concerns about the potential burden of a sales tax increase on lower-income citizens. She said that's why transit fares would be free or reduced for poor, disabled, senior and under-18 residents.

The funding would cover capital infrastructure costs and sustain operations and maintenance funding for 50 years, with 30 percent of the money set aside for future expansion of the transit corridors.

In addition to new tax revenue, the plan calls for a combination of federal grants, bonds and fare revenues.

Some of the mayor's proposed tax increases were first made available to cities within Gov. Bill Haslam's road funding package, which he signed into law earlier this year.

In response Tuesday, the Nashville Tea Party and the fiscally conservative Beacon Center of Tennessee both criticized the price tag and the choice of light rail.

Ben Cunningham, Nashville Tea Party president, said he's worried these kinds of projects can run over their budgets and timelines. He said light rail isn't the best option because of new ridesharing technologies and driverless cars coming in the future.

"If the costs balloon out of control, like they have in many other places, then this will just be a down payment," Cunningham said.