Experts are giving Michigan's roads a poor rating going into 2018 - they've earned a D- grade, according to a new report released Tuesday by the American Society of Civil Engineers Michigan Section.

The report gave Michigan an overall D+ grade for its infrastructure system based on an analysis of 13 categories of the state's infrastructure. When grading, the engineers behind the report considered eight criteria: capacity, condition, funding, future need, operation and maintenance, public safety, resilience and innovation.

ASCE-Michigan's findings show the categories in the best repair -- the state's solid waste, navigation and aviation systems -- earned a C or C+ grade, which the report classifies as mediocre or requiring attention.

But roads, as well as the state's stormwater system, fared the worst of all in the report, earning the lowest grades of the bunch with a D-. Part of that reasoning came from the fact that 39 percent of Michigan's 120,000 miles of roads are rated in poor condition, while another 43 percent are rated in fair condition.

The report was compiled by a committee of civil and environmental engineers affiliated with ASCE-Michigan.

At a Tuesday press conference outlining the results, Steve Waalkes, co-chair of the society's report card committee, said the last Michigan-specific report card ASCE-Michigan was rolled out in 2009, when the overall grade was a D. He said on paper, it's technically a slight improvement, but said in reality, "we haven't gotten any better - it's pretty much status quo."

"As our infrastructure systems continue to surpass their intended lifespan, Michigan residents and policy makers must decide if we collectively value the personal and economic advantages that come from a robust infrastructure network," he said.

State lawmakers in 2015 pushed through a plan to help pump additional funding into roads, although experts have said that's only a first step in addressing Michigan's critical infrastructure needs.

A bill pushed through the state legislature in 2015 approved vehicle registration fees by 20 percent, the gas tax by 7.3 cents per gallon and the diesel tax by 11.3 cents. Those comprise roughly $600 million in new revenue. The legislature, in annual budgets, will start shifting another $600 million from the general fund into roads. The total boost for road funding will reach $1.2 billion by 2021.

That money goes to the Michigan Department of Transportation as well as county and local governments for road improvements.

Sen. Tom Casperson, R-Escanaba, is chair of the state Senate Transportation Committee. On Tuesday, he said he "started sweating a little bit" when he read through the report's results.

Although Casperson will be term-limited out of office at the end of 2018, he said he is "all in" on any potential solutions to fully funding infrastructure needs, including aquiring additional funding and reducing regulations that drive up costs.

But he noted that it's not easy to come to a consensus.

"This issue is a tough one for everybody," he said. "We have to do something."

Lance Binoniemi of the Michigan Infrastructure and Transportation Association said he doesn't think it's a surprise to anybody that Michigan's infrastructure isn't doing well.

He said the data shows infrastructure repair needs to be the number one priority of elected officials, especially considering recent major infrastructural failings in Michigan such as the Flint water crisis and the sinkhole that developed in Fraser in late 2016.

"Campaign promises aren't enough," he said. "We still haven't found a major long-term solution in the legislature."

Below are the grades for every infrastructure category studied for the ASCE-Michigan report. Read the full report at www.infrastructurereportcard.org/michigan.