Relatively high fuel prices and lousy roads.

It's been a long-standing one-two punch for Michigan motorists — one that hasn't changed significantly under the 2015 road funding deal that is still being ramped up.

Here are five reasons Michigan has lousy roads:

1. Michigan's gas prices are high relative to nearby states.That makes it harder to increase fuel taxes to pay for road repairs.

On Monday, the average Michigan gas price was $2.59 per gallon, compared with $2.43 per gallon in Ohio, $2.47 per gallon in Wisconsin, and $2.48 per gallon in Indiana, according to GasBuddy.

A major reason? Michigan has taxes on fuel that do not support the roads.

Carl Davis, a senior analyst at the Institute on Taxation and Economic Policy in Washington, D.C., said Thursday that Michigan is one of only four states, with Indiana, Illinois and Hawaii, that fully apply their general sales tax to fuel sales.

Unlike fuel taxes, which are targeted to support road maintenance and repairs, Michigan's 6% sales taxes mostly supports Michigan schools.

In neighboring Ohio, of the 46.4 cents in taxes paid on a gallon of gas, 28 cents is a state fuel tax that supports the roads and the other 18.4 cents is the federal fuel tax.

But in Michigan, where 60.78 cents in taxes are paid on a gallon of fuel, only 26.3 cents is state fuel tax used to support the roads, 18.4 cents is the federal fuel tax, and the other 16 cents is sales tax.

2. State spending on roads, though increasing under the road funding deal, also is below that of neighboring states.

A 2018 study from the Reason Foundation, based on 2015 data, said Michigan ranked 33rd among the 50 states for total spending per mile of state-owned road. The $207,162 spent per mile in Michigan was behind neighbors Ohio, which spent $213,040 per mile, and Wisconsin, which spent $250,040, the report said. Michigan was ahead of neighbor Indiana, which spent $196,848, said the report, which included not just construction and maintenance costs but amounts spent on law enforcement and safety.

Other analyses have shown Michigan to be even further behind many of its neighbors on highway spending.

The Urban Institute said in a recent report, using 2015 census data, that state and local highway and road spending in Michigan and neighboring Indiana is less than $500 per person. Neighbor Ohio spends between $500 and $600 per person, while Wisconsin spends more than $700 per person, the report said.

Michigan's 2015 road funding deal, which will raise an extra $1.2 billion a year for roads once it is fully implemented, increased the state's 19-cent-per-gallon fuel tax by 7.3 cents per gallon and provided for future increases in the tax to keep pace with inflation. It also hiked vehicle registration fees by 20% and will eventually earmark $600 million in annual general fund spending for roads.

But experts said the package was more than $1 billion a year less than what the state needs. Michigan Department of Transportation Director Kirk Steudle has said Michigan roads will continue to deteriorate with the increased funding, just not as quickly as they otherwise would have.

3. Michigan's roads and bridges take a pounding from heavy trucks.

Michigan's gross weight limit for trucks — 164,000 pounds — is more than double the federal weight limit and the highest in the nation.

State officials say Michigan reduces the impact of those heavy loads by requiring truckers to spread their loads over more axles.

But as the Free Press reported in 2013, truckers can also pay fees of $50 for a single trip or $100 for multiple trips to obtain permits to haul much heavier loads — ones that in some cases exceed 1 million pounds.

In 2012, MDOT issued 6,992 special permits — an average of 19 each day — for trucks weighing more than 164,000 pounds, a Free Press investigation found. About 2,820 of those permits were for trucks weighing 200,000 pounds or more.

4. Michigan weather, combined with soil conditions around metro Detroit.

As this spring has again demonstrated, Michigan's roads are never worse than when they are heaving from frequent freezes and thaws. Michigan is not unique in experiencing such weather turns, but because of its highly variable weather and the moderating effect of the Great Lakes, it gets more freeze and thaw than most states do.

Transportation officials say the weather pattern poses an extra challenge when coupled with sometimes swampy soil conditions around metro Detroit, which can combine to undermine road foundations.

5. Sometimes inadequate state oversight of contractors' performance.

In 2015, Michigan's auditor general found that warranties used on many Michigan road projects were ineffective because MDOT didn't consistently inspect and follow up on the completed projects and make sure contractors corrected deficiencies.

"Our review ... identified 48 of 92 expired warranty projects that needed corrective action," the report said. "As of June 30, 2014, 24 of the warranties had been expired for over one year without MDOT having addressed the corrective action."

The Transportation Department pledged to improve its warranty oversight after the audit was released, while also downplaying the significance of the findings.

Steudle, the MDOT director, said the potential costs shifted from the contractor to the state as a result of problems the auditor identified amounted to tens of thousands of dollars or a low six-figure number, but MDOT oversaw the completion of 1,340 road and bridge construction projects costing $1.4 billion during the period covered by the audit.

MDOT spokesman Jeff Cranson said MDOT has been recognized as a national leader in the use of road warranties, both in terms of the number of warranties and its years of experience administering them.

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