The state released a new report highlighting bridges that need updating and two Benzie County sites are on the list.
The Michigan Department of Transportation (MDOT) posts the bridge safety reports on the 4,399 highway bridges greater than 20 feet in length.
MDOT has posted bridge safety reports online since August 2007. State bridge information can be downloaded by route number and/or county, and are current as of May 31, 2011. Only highway bridges greater than 20 feet in length are included; ratings for pedestrian, railroad and locally owned bridges are not included. MDOT is updating bridge condition information on the Web four times a year.
"MDOT works year-round to inspect highway bridges across Michigan and monitor their condition scores and sufficiency ranges," said State Transportation Director Kirk T. Steudle. "We are delivering on our commitment to be open and transparent by regularly reporting on the condition of bridges and overpasses."
National Bridge Inspection Standards require MDOT to inspect bridges every two years. The Mackinac, International, and Blue Water bridges are inspected annually, exceeding federal requirements. These three bridges are managed by bridge authorities, and their ratings are not included in the list MDOT has posted to the Web.
MDOT employs more than 20 bridge inspectors who have specialized training and work in teams of two. Bridge inspectors use a variety of tools to assess bridge safety and structural integrity. The types of inspection performed include bridge safety inspections, fracture critical inspections, fatigue-sensitive inspections and underwater inspections. Non-destructive evaluation and bridge monitoring also is done as needed. Techniques used include calipers to measure the thickness of steel, ultrasonic testing to check for defects in steel, sounding to detect concrete separation, and monitoring bridge deflections and response to load.
Of the 4,399 bridges included in the May 31 report, 378 are classified with the engineering term of "structurally deficient," meaning they may require rehabilitation or replacement at some time in the future; and 843 are classified as "functionally obsolete," meaning their design is outdated and may require modernization at some time in the future.
Two bridges in Benzie County were classified as structurally deficient. Those include one on M-22 over the Platte River, 7.5 miles southwest of the Leelanau County line. The second bridge of concern is also over the Platte River on U.S. 31 just west of Honor.
You can see the bridge report for your area by CLICKING HERE.
