LANSING — Michigan roads will continue to erode and cost taxpayers $25 billion per year by 2031 if lawmakers don’t commit to more money for upkeep, according to a national transportation report released Thursday.

Conducted by Washington, D.C.-based nonprofit research group TRIP, the report evaluates Michigan’s current road and bridge conditions and predicts the amount of money the state would need to fix them.

The analysis found that roughly a quarter of Michigan’s major roads and highways are in poor condition — and the future is far worse if spending isn’t increased.

Already, poor roads cost the state $19.3 billion per year in maintenance, crashes, backups and car repairs, the report claimed.

“This report shows what people all over Michigan already know — transportation and infrastructure funding is critical for our future,” Lansing Mayor Andy Schor, a Democrat, said in a statement Thursday.

“Local governments across Michigan desperately need funding from our state and federal government to invest in our crumbling roads, streets, bridges, and aging underground infrastructure.”

Founded in 1971, TRIP is a national nonprofit research group that receives money from insurance companies, transit and highway construction businesses and labor unions, according to its website.

The report comes weeks after Democratic Gov. Gretchen Whitmer and the Republican-led Legislature struck a $4.7 billion deal to spend state revenue surplus and federal stimulus funds on infrastructure improvements.

At the federal level, the $1.2 trillion federal infrastructure package, passed by Congress in November, brought Michigan nearly $8 billion in infrastructure funding.

The $4.7 billion plan includes more than $1.7 billion on drinking water and wastewater management systems, $450 million on parks and trails, $317 million for road and bridge repairs and $250 million for broadband expansion in unserved areas.

Michigan spends an average of $1.3 billion every year on road work, according to the analysis that used data from the Michigan Department of Transportation and the Federal Highway Administration.

Without increased funding, the percentage of roads and highways in poor condition will more than double to 49 percent by 2031, the report estimates.

To maintain the status quo of road conditions, Michigan lawmakers must spend $2 billion per year during the next decade, the report estimates. To make “significant” improvements by 2031, the annual price tag is estimated to be $2.8 billion per year.

Similarly, more than 1,200 of the 11,195 bridges in Michigan — or 11 percent — are rated as “structurally deficient,” according to the report.

The state now spends an annual average of $232 million on bridge repairs, but would need to spend an annual $418 million — almost double the current investment — to prevent the situation from worsening.

The state must also significantly increase its funding to improve traffic safety and reduce traffic congestion, the report argues.

The increase in transportation investments will save the state money in the long run, the report estimates.

Wendy Block, vice president of business advocacy and member engagement for the Michigan Chamber of Commerce, called infrastructure improvements a “fundamental building block” of Michigan’s economy.

“While Michigan has made notable, important strides, it’s imperative that we continue to look for bipartisan, long-term solutions to ensure we are making forward progress.”

Whitmer won election in 2018 in part because of her campaign pledge to “fix the damn roads.”

In 2019, she proposed a 45-cent fuel tax hike that would have made Michigan’s gas tax — already the fifth-highest in the nation — tops among all states.

The plan would have raised $2.5 billion per year, but it was so unpopular that even Democrats in the Legislature didn’t support it.

Whitmer has since retooled her efforts, launching a $3.5 billion bond program, circumventing the Republican-led Legislature to borrow money to fix the state’s highways and bridges.