Bridges
About the measures
Bridge condition is assigned during inspections performed at least every two years on all state highway bridges. Ratings combine deck, substructure, and superstructure evaluations. MnDOT reports progress against targets for the percent of bridges in poor condition and good condition. Bridges in good condition generally receive routine maintenance, while bridges in poor condition are monitored more closely and eventually scheduled for major repair, rehabilitation, or replacement. Bridges rated as “poor” are safe to drive on, but they are near the point where significant investment in repair or replacement is necessary.
A bridge inspection is considered on-time if it is completed within 30 days of its calendar due date. All of Minnesota’s MnDOT-owned bridges receive scheduled safety inspections as required by state and federal rules and regulations. In general, bridge inspections typically occur on two-year cycles, but sometimes a small number are delayed past their due date because of weather or a scheduling issue. Some structures are on shorter or longer inspection cycles, depending on current condition, type of design and materials used in construction.
Recent trends
In 2022, 6.3% of National Highway System (NHS) bridges were rated as being in poor condition, which exceeds the statewide target of 5%. The increase from 2020 to 2021 is due in large part to the Blatnik Bridge in Duluth falling into poor condition (the Blatnik Bridge, connecting Duluth and Superior, WI, is Minnesota's second longest bridge).
For non-NHS bridges, 4.2% of non-NHS bridges were in poor condition, which is in line with previous years and better than the statewide target. However, according to Capital Highway Investment Plan (CHIP) projections as of September 2023, the proportions of NHS and non-NHS bridges in poor condition are expected to increase and exceed the statewide targets by 2033.
Nearly all (99.9%) inspections of MnDOT-owned bridges were completed on-time, which has been consistent over the last five-year period. Since 2013, MnDOT has completed bridge inspections on time 99% of the time.
Where we want to go
The statewide target for the percent of bridges in poor condition is 5%. As guided by the Transportation Asset Management Plan (TAMP) and its focus on life cycle planning, monitoring, and measuring the condition of these assets helps MnDOT and its partners strategically build, manage, maintain, operate, and adapt the transportation system. Because bridges are large, complex, and expensive assets that deteriorate over time, MnDOT also proactively performs preventative maintenance activities such as flushing, crack sealing, joint maintenance, and spot painting.
MnDOT strives to achieve 100% of on-time bridge inspections. However, delays can occur due to weather, conflicting construction activities, or high priority reactive maintenance activities. Providing accurate data from these inspections allows MnDOT and its transportation partners to better plan for bridge improvements, maintenance, and operations throughout the state.