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News and quick-hit commentary from around mid-Michigan ... from the Morning Sun.

Saturday, July 05, 2008

Gratiot County's lowest-rated bridge

The lowest-rated bridge in Gratiot County is just east of Riverdale and carries Lincoln Road across the Pine River. It carries a federal sufficiency rating of 2.0.
The “federal sufficiency rating” is a complex formula used to determine federal bridge program funding eligibility.
The sufficiency rating combines the condition and functional adequacy data collected on every bridge into a single number. Sufficiency rating values range from 0 (low) to 100 (high).
If the sufficiency rating on a bridge is 50 or less and it is designated as “structurally deficient” or “functionally obsolete,” the bridge qualifies for federal replacement funding.
A low sufficiency rating number does not necessarily mean that the bridge is in need of immediate repair.

Like many bridges of its era, it is a concrete bridge. But weathering has taken a heavy toll on the Riverdale bridge, exposing the steel reinforcing rod at the east end of the bridge.

Huge chunks of the facing have fallen off the west end of the bridge, as well, with gravel from the conglomerate collecting at the bottom of the concrete truss.

The bridge features window-like openings in the concrete truss that provides strength to the structure, but now, the edges are crumbling.

The steel rebar is rusty, but apparently continues to provide strong reinforcement.

The bridge is classified as "structurally deficient," but bridge engineers are quick to point out that that term doesn't necessarily mean unsafe. The bridge is narrow, on a county primary road, and carries a substantial amount of traffic, including heavyweight agricultural traffic.

The Lincoln Road bridge is a beautiful design that compliments the beautiful setting on the Upper Pine, but its problems are obvious.

Click here for a fully interactive map

Mid-Michigan has many "structurally deficient" bridges. Click on a placemarker near you to see them in your area.

Read Susan Field's story on mid-Michigan's bridges in Sunday's Morning Sun!


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