LANSING — The Michigan Senate approved a bill Tuesday to require the state Department of Transportation to explore the feasibility of implementing toll roads and bridges.

The bill, supported by the Department of Transportation, would direct the department to hire outside consultants to conduct a study recommending optimal tolling rates, locations and revenue projections in an 18-month project that would begin when the legislation became law.

The vote on the legislation comes one day before Gov. Gretchen Whitmer is set to deliver her second State of the State speech, during which she’s expected to outline a new proposal to raise money to fix the state’s roads and bridges.

Last year, the Democratic governor proposed raising the gas tax by 45 cents per gallon, but the plan went nowhere in the Republican-led Legislature.

Senate Majority Leader Mike Shirkey, R-Clarklake, told reporters Tuesday he believes toll roads need to be studied, and “we’re still in the mode where no option should be eliminated completely.”

“You can’t talk about funding roads for perpetuity without also including policies that cause the legislature to have to pay attention to how those things are performing,” Shirkey said of the bill package, which includes the toll road study and other transportation-related bills. “That’s what this package is about and I think it’s fantastic.”

The proposal still needs approval from the House and Whitmer.

The study would also include a report on the number of out-of-state drivers that usually use Michigan highways; which highways would be best suited for a toll; and any potential discounts or credits to decrease the impact of tolling on local drivers.

Senate Minority Leader Jim Ananich, D-Flint, said most members of his caucus support finding out whether tolling would work for Michigan.

Critics have long said tolls would disproportionately affect state residents since Michigan is a peninsula largely cut off from national interstate traffic.

“A lot of us believe we should look at every option on the table and give it a full vetting,” Ananich said. “We’re not a pass-through state… so tolling isn’t always the option that people think it is, but we wanted to get a feel for that.”

Michigan already has tolls on certain bridges, including the Mackinac Bridge connecting the lower and upper peninsulas, the Blue Water Bridge between Sarnia and Port Huron and International Bridge between Sault Ste. Marie and Ontario. Several nearby states, including Ohio, Indiana and Illinois, also have widespread toll road systems.

One obstacle to the toll plan is they usually aren’t allowed on roads built with federal funding, which include most of Michigan’s freeways.

However, the Trump administration, like Obama before him, has expressed interest in easing those restrictions as states struggle to raise enough revenue to maintain infrastructure with fuel taxes.

The federal government recently expanded a pilot program for states that want to try using tolling to fix crumbling freeways.