LANSING — A report issued June 6 by the County Road Association of Michigan (CRAM) revealed that more than 17 percent of bridges located on local roads are structurally deficient; 16 percent are posted with reduced weight restrictions and 62 bridges are closed to vehicle traffic.

“Michigan’s state and local economies rely on off-system bridges,” CRAM Director John Niemela said. “These bridges support school buses, emergency response vehicles, agriculture commodities, the tourism industry and local commerce.”

Michigan has a total of 8,633 local bridges under the jurisdiction of a municipality or county road agency.

More than half of these bridges (4,594) are off-system bridges, meaning they are located off the federal-aid road system.

Of these bridges, 789 are structurally deficient, 743 are posted with reduced weight restrictions and 62 are closed to traffic.

Since 1978, federal law has required each state to spend a minimum of 15 percent of its federal bridge funding on bridges which are not on the federal-aid road system.

This requirement was put into place because almost 50 percent of the nation’s bridges are not on the federal-aid system.

These bridges tend to be in poorer condition than federal-aid bridges and less funding is available for rehabilitation and replacement of these bridges.

Congress is currently discussing eliminating this program.

The off-system bridge program is a key point of contention in reauthorization of the Federal Highway Bill.

“Even with the current 15 percent set-aside in federal funding, and a small portion of Michigan’s gas tax dedicated to local bridges (approximately $31 million annually), current funding does not meet the needs of our aging infrastructure,” Niemela said.

“Deteriorating off-system bridges are causing economic frustrations as areas of the state are effectively cut off from commerce, and increased response times during emergencies are a serious concern.” Earlier this year, Gov. Rick Snyder announced the number of structurally deficient bridges in Michigan would be a measure used on the state’s dashboard to determine Michigan’s economic strength. In 2010, 8.7 percent of state-owned bridges and 16.6 percent of county and local bridges were structurally deficient, resulting in 13.15 percent of Michigan bridges being rated as structurally deficient.