As Michiganders hit the road this holiday weekend, state lawmakers are brainstorming ways to help close the state’s $3.9 billion road funding gap.

One idea is the Road Usage Pilot Program, to add tolls and mileage fees for using some of the most heavily traveled highways in the state. The pilot study is still in early stages of discussion, but it could mean a 6 cents per mile fee for drivers, which could raise $1 billion to fix Michigan’s decaying roads.

Michigan House Transportation Budget Chair, state Representative Ranjeev Puri, says road funding comes from a variety of sources, but it isn’t enough.

“When we all purchase a vehicle, we go pay a registration fee,” Puri said. “So, those registration fees help fund our roads. There’s also some money from the sales tax that goes to the roads, and there’s also money from the gas tax. We’ve just never come up with a formula that fundamentally meets the needs of the state.”

Puri adds the rise in electric vehicle use equals fewer people buying gas, which means less gas tax revenue.

More than 1.3 million Michigan residents are expected to travel 50 miles or more from home this Memorial Day weekend, according to AAA. That’s up 4% from last year.