- The Governor's directive is to inspect all bridges on the trunk highway system in priority order.
- The goal is to complete all inspections by December 1, 2007.
- The bridge inspections will be completed by mobilizing Mn/DOT equipment and staff.
- Mn/DOT has supplemented its resources by entering into an emergency contract with PB Americas, Inc. to perform bridge inspections.
- All fracture critical bridges on the Trunk Highway and local State-Aid system in Minnesota will receive an in-depth inspection this year.
- Owners of private and off-system fracture critical bridges have been advised to perform an in-depth inspection this year.
- Local agency personnel have been advised to also inspect structurally deficient bridges in an expeditious manner.
- Mn/DOT has supplied all agencies with lists identifying structurally deficient bridges within their jurisdiction.
Terms and definitions used in these documents
2007 Inspections: Critical Findings Report
- All 227 fracture critical and special feature bridges have had inspections completed this year. 222 were in-depth inspections and 5 were routine inspections.
- All 3875 Trunk Highway bridges have had a routine inspection completed this year.
- All 106 Trunk Highway bridges classified as structurally deficient have been inspected this year.
- All 843 local bridges classified as structurally deficient have been reported as inspected. An additional 42 of these bridges have been reported to be replaced this year.
Mn/DOT is reviewing the adequacy of the design of gusset plates for all 25 truss bridges on the state system. In-depth physical inspections are also being conducted to confirm the current condition of the gusset plates. If concerns with the gusset plates are found during inspections, the design review is reevaluated to determine if the gusset plates remain adequate.
Gusset plate review and inspections is the result of information released by the National Transportation Safety Board in January indicating that the original design of the gusset plates on the I-35W bridge was inadequate. The Federal Highway Administration subsequently asked states to recalculate the load bearing capacity of their truss bridges when major work was planned.
Gusset plate reviews are now complete.
- 25 have been completed
- 3 – required repair or modification (Blatnik, Winona, Hastings)
- 1 – (St. Cloud) remains closed and replacement has been accelerated to 2008
- 21 – require no repairs to remain open to legal loads. Report summaries are being prepared.
Highway 23/Division Street (DeSoto) Bridge over the Mississippi River in St. Cloud – Bridge was closed on March 20, 2008, due to distortions found in gusset plates at three locations of the bridge. Bridge will be reconstructed beginning in 2008.
Interstate 535/John A. Blatnik Bridge between Duluth, Minn. and Superior, Wis. – Two lanes of traffic were closed on May 6, 2008, after load calculations and field inspections discovered that gusset plates in eight locations on the bridge did not fully meet load requirements. Work began June 9 to install angle irons to strengthen the gusset plates and was completed June 21, 2008.
Minnesota Highway 43/Wisconsin Highway 54 Bridge over the Mississippi River in Winona – Bridge was closed on June 3, 2008, due to rust and corrosion found in gusset plates at several locations of the bridge. Repairs to the gusset plates were completed June 21, 2008.
The Highway 61 Bridge over the Mississippi River at Hastings required additional bracing be added to the edges of a few gusset plates. That work was completed under a bridge painting and preservation contract which had previously been scheduled. During the painting project an additional gusset plate location was discovered that also required strengthening due to corrosion. All gusset plate work has now been completed.
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