DETROIT -- A statewide study by the Michigan Infrastructure Transportation Association reveals that 28 percent of the state's bridges are either structurally deficient or functionally obsolete.

The study reported two key points:

Of the 4,414 bridges that are the responsibility of the Michigan Department of Transportation, 1,332 -- or 30 percent --are either functionally obsolete, meaning their design is outdated, or are structurally deficient, which indicates a bridge has deteriorating beams, a crumbling deck or other problems that could force its closure.

And, among the 6,417 bridges that are the responsibility of local governmental units, 1,723 -- or 27 percent -- are in need of bridge maintenance or repair.

Here’s a breakdown of poor bridges:

Highest percentage of MDOT bridges in poor condition:

1. Wayne County has 63 percent in poor shape (431 of 684 bridges) 2. Saginaw County has 57 percent (55 of 97) 3. Emmet County has 56 percent (five of nine) 4. Antrim County has 50 percent (one of two) 5. Kalamazoo County has 48 percent (30 of 63)

Highest percentage of local bridges in poor condition (of all counties with more then one bridge):

1. Marquette County has 55 percent (54 of 98) 2. (tie) Genesee County has 49 percent (87 of 179) Washtenaw County has 49 percent (66 of 135) Mason County has 49 percent (17 of 35) 3. Ingham County recorded 46 percent of local bridges in poor condition (44 of 95)

Highest percentage of all bridges in poor condition:

1. Wayne County has 56 percent of its bridges listed in poor condition (574 of 1,026) 2. Genesee County has 48 percent (177 of 370) 3. Emmet County has 44 percent (12 of 27) 4. Marquette County has 43 percent (57 of 133) 5. Washtenaw County (99 of 248) and Charlevoix County (six of 15)

In a related study specifically focusing on Oakland County, MITA reported that one in five bridges in the county were considered in poor condition.

Some of the ones listed in the poorest condition were:

13 Mile Road over the Rouge River in Franklin.
Middlebelt Road over Pebble Creek in Farmington Hills.
12 Mile Road over the Rouge River in Southfield.
Avon Road and Livernois Road over the Clinton River.

The study reported that Oakland County has 280 bridges maintained by MDOT, and 107 of themare in need of repairs.

The county also has 166 bridges that are cared for by local governmental units, and 58 of them are in need of repairs.