Illinois voters Tuesday night approved the so-called “Safe Roads Amendment” that ensures billions of state dollars will be set aside for transportation projects — but according to opponents — could cause financial strain in the future.

In early returns, with about 86 percent of precincts reporting throughout the state, 79 percent voted to add Section 11 to Article IX of the Illinois Constitution.

To pass, the amendment had to be approved by 60 percent of the voters or by more than 50 percent of all ballots cast.

State Sen. William Haine, D-Alton, the chief Senate sponsor of the amendment legislation, said there was “great merit” in it, because it forces lawmakers to use transportation-related fees such as license-plate registration payments and motor fuel taxes solely for roads, bridges and the CTA.

“I believe it’s good public policy,” Heine said after the amendment was approved Tuesday night. “It was necessary because of previous well-intentioned but improvident fiscal decisions.”

Others weren’t so sure and suggested voters only punched “yes” because of what they say was a deceptive marketing campaign.

“You really don’t know what you’re going for,” University of Chicago’s Amanda Kass said of the vague wording of the amendment.

The “lockbox” amendment, anchored in an atypical truce between Gov. Bruce Rauner and House Speaker Michael Madigan, received a “no vote” recommendation from major Chicago newspapers, including the Sun-Times, and has been criticized for misleading voters into believing it’s a measure mostly backed by everyday citizens.

The “Citizens to Protect Transportation Funding” political committee is wholly funded by big trade unions and major business groups and as Kass says, it is hard to determine exactly how much more money will go toward transportation.

Sources told the Sun-Times the amendment was an idea hatched by the Illinois Chamber of Commerce and the Illinois Road and Transportation Builders Association.

The bulk of the $4 million raised by the committee has come from groups that are not obligated to identify who they are.

Those who have opposed the amendment have pointed that by placing money into a “lockbox,” it could keep the already cash-strapped state from getting out of a fiscal bind or spending in other areas that are vital to the state.

Chicago can also lose flexibility in spending, said Kass, assistant director of the Center for Municipal Finance at U of C’s Harris School of Public Policy.

“It could create a shortfall elsewhere and it will impact local governments,” she said.

Heine called the arguments against the amendments “silly.” “What should we do? Do we have a bake sale?” he said.

In an emailed statement, Ryan Keith, a spokesman for the Transportation for Illinois Coalition, which supported the amendment, said, “With this vote, our investment in roads, bridges, transit and other modes of transportation will be protected, our transportation networks will be stronger and safer, and our policymakers will need to get serious about addressing the serious challenges Illinois faces.”

Kass said she believes it was this type of “messaging” that helped drum up support for the amendment.

“There’s a clear need for infrastructure. Everyone is hearing this message of increased funding and there’s a sentiment that lawmakers can’t do anything,” Kass said.