Tag Archives: bridge

Report examines condition of Minnesota’s roads and bridges to inform future investments

Reprinted from CTS News October 6, 2026

From freight, commercial, and public transit to personal commuters, delivery drivers, and emergency services, millions of vehicles travel Minnesota roadways each year. As the number of drivers on the roads grows, ensuring safe and reliable transportation infrastructure is crucial. A recent analysis performed by the Transportation Policy and Economic Competitiveness (TPEC) Program examined the performance and condition of Minnesota’s roadways at the county level from 2018–2024.

Using data regularly collected and maintained by the state, the TPEC team — led by Camila Fonseca-Sarmiento, director of fiscal research at the Institute for Urban and Regional Infrastructure Finance at the UMN’s Humphrey School of Public Affairs and a CTS scholar — assessed condition, safety, and performance trends of Minnesota transportation infrastructure and how these measures have changed over time. Bridge and pavement conditions were categorized as being in good condition, fair condition, or poor condition.

Pavement conditions and trends

The data examined focused on two roadway networks in Minnesota — the National Highway System (NHS) and the County State-Aid Highway (CSAH) system. The NHS, which includes interstates and local and national highways, makes up just 10 percent of statewide lane miles but carries a majority of vehicle traffic. The CSAH system carries significantly less traffic but is more than double the length of the NHS. Pavement types across these roadway networks were evaluated by surface distress or visible defects, ride quality or pavement smoothness, the overall condition of pavement, and the estimated time until the end of the pavement’s service life. Among the analysis’s key insights:

  • More than 80 percent of NHS roads and more than 60 percent of CSAH system roads are in good condition.
  • The CSAH system has more than double the number of roads in poor condition than the NHS.
  • Interstates consistently have the highest pavement quality.
  • Counties with an interstate highway tend to have the most vehicle traffic and pavement in good condition.
  • Counties in northwest Minnesota have the most CSAH roads in good condition while the metro area has the fewest.

Bridge conditions and trends

The team’s research found that the bridge network across Minnesota, comprising 13,500 bridges, remains generally well maintained. Some key trends identified:

  • Bridge conditions have been slowly declining since 2019, with the number of bridges in fair condition increasing.
  • As the population grows, the share of bridges in good condition declines.
  • Counties in northwest Minnesota have a higher rate of bridges in poor condition.

These insights indicate that more bridges will require greater levels of maintenance and preservation efforts in the years to come.

Crash trends

The COVID-19 pandemic altered the driving habits of many — as more people stayed home, fewer vehicles traveled the roads. While the total number of crashes across Minnesota has declined since 2020, the severity of crashes has risen slightly. Among the key crash trends from the report:

  • Minnesota counties average 929 crashes per 100,000 people.
  • Counties in southwest Minnesota have higher rates of property damage, injury, and fatal crashes.
  • Counties in northwest Minnesota have lower rates of property damage, injury, and fatal crashes.
  • Between 2019 and 2023, crashes statewide causing property damage decreased by 22 percent and fatal and injury crashes decreased by 13 percent.
  • Severe weather or wildlife encounters may be contributing to increased crashes in some counties.
  • As the population grows, crash rates increase.
Minnesota county map shaded by rates per 100,000, ranging from 0–500 to 1501+, with some areas marked NA

“The findings emphasize the importance of continued monitoring and investment in Minnesota’s transportation infrastructure,” Fonseca-Sarmiento says. “Understanding how roadway and bridge conditions vary throughout the state is essential for prioritizing resources when investing in the transportation network and improving safety. As transportation demands continue to evolve, data-driven decision-making will remain crucial to ensure a reliable and resilient transportation network for Minnesotans.”

— Krysta Rzeszutek, CTS digital editor

Related MnDOT Research from 2026

New methods to determine safe bridge loading will help keep Minnesota’s truck freight moving

April 10, 2023

When transportation officials determine which route a heavy truck should take, their aim is maximizing efficiency while ensuring safety. Detours around bridges on critical freight routes increase fuel and labor costs for the trucking industry—and eventually hit consumer pocketbooks, too.

Continue reading New methods to determine safe bridge loading will help keep Minnesota’s truck freight moving →

Updating Load Ratings for Shingle Creek Slab-Span Bridges

Detours around bridges in a critical freight transportation route create costs to the trucking industry, taxpayers and state economy. New load rating factors for the slab-span bridges across Shingle Creek will give MnDOT more flexibility in managing truck traffic and keeping freight moving efficiently.

Continue reading Updating Load Ratings for Shingle Creek Slab-Span Bridges →

New Project: Bridge Low Slump Concrete Overlay Mix Design for Mobile Mixers

In recent years, MnDOT has seen an increase in cracking of low slump overlays. Cracking of overlays allows chlorides to get into the bridge deck which leads to deterioration of the reinforcement and eventual delamination or spalling.  This means that the bridge deck needs to be repaired or even replaced before the service life has been reached. 

What is a low slump overlay? A low slump overlay is a technique used by DOTs to extend the life of bridge decks. They are typically 2″ thick and designed to provide low permeability.

Continue reading New Project: Bridge Low Slump Concrete Overlay Mix Design for Mobile Mixers →

GFRP Rebar Shows Promise for Use in Bridge Decks

Reinforced concrete bridges are built to handle heavy loads and routine traffic for 75 years or more. But bridges in climates like Minnesota’s are exposed to moisture and chlorides from road salts that may penetrate these structures and corrode the steel.

In a recently completed research project, funded by MnDOT and the Local Road Research Board, researchers studied a rural bridge built in 2017 near Elgin, MN, that used glass fiber–reinforced polymer (GFRP) rebar in the bridge deck. They found that GFRP performed well, proving sufficiently strong for use as an alternative to corrosion-susceptible steel rebar.

Continue reading GFRP Rebar Shows Promise for Use in Bridge Decks →

Methods to Mitigate Bridge Corrosion Show Mixed Results 20 Years Later

Well-documented efforts undertaken two decades ago to mitigate corrosion of a Highway 394 reinforced concrete bridge have given researchers the perfect scenario for evaluating the treatments’ long-term effectiveness. The test results are mixed: State-of-the-art methods for electrochemical chloride extraction and fiber-reinforced polymer wrapping of bridge elements performed well in combination, but poorly in isolation.

Continue reading Methods to Mitigate Bridge Corrosion Show Mixed Results 20 Years Later →

Putting Research Into Practice: New Tool Estimates Bridge Construction Time

A new spreadsheet tool developed by the Minnesota Department of Transportation draws on historical data to help project engineers better estimate bridge construction time. The method allows users to project time-frames based on bridge design elements, work scheduling and other inputs, utilizing estimates from comparable projects in a 10-year database of bridge-building data.

Continue reading Putting Research Into Practice: New Tool Estimates Bridge Construction Time →

Detecting Corrosion Early Extends Service Life of Bridge Paint Coating

An evaluation of five maintenance paint coating systems on Minnesota steel bridges with localized corrosion found that each maintenance coating performed well, and, if corrosion is identified early and maintenance painting occurs, the service life of the paint coating system can be extended five years before repainting is required. Based on the test data, researchers recommended an update to MnDOT’s Bridge Maintenance Painting Manual that includes guidance on when to apply maintenance paint coatings and when to remove paint and recoat bridges.

Continue reading Detecting Corrosion Early Extends Service Life of Bridge Paint Coating →

Using Debonded Strands to Reduce End Stress in Bridge Beams

A new MnDOT-funded research study has found that most agencies in states with weather similar to Minnesota’s use debonded strands in prestressed concrete bridge beams. MnDOT may begin piloting debonding as an alternative to draping, which manufacturers claim is time-consuming, challenging to worker safety and expensive.

Continue reading Using Debonded Strands to Reduce End Stress in Bridge Beams →

New Project: Use of Innovative Technology to temporarily Deter Bat-Bridge Use Prior to and During Construction

MnDOT has funded a study to evaluate the use of non-lethal ultrasonic acoustic devices to temporarily deter bats from bridges before and during construction projects.

Continue reading New Project: Use of Innovative Technology to temporarily Deter Bat-Bridge Use Prior to and During Construction →