As a result, NTSB established new safety regulations, from design to inspection
About five years ago more than 100 cars were traveling an I-35W bridge during a Minneapolis rush hour when it suddenly collapsed, dropping cars into the 15-foot-deep Mississippi River below.
The collapse killed 13 people and injured another 145. It was one of the worst bridge disasters in U.S. history.
A National Transportation Safety Board investigation revealed the probable cause was inadequate load capacity — a simple design flaw in metal plates that help connect one steel beam to another.
As a result of the collapse, the NTSB set new safety recommendations for bridge design plans, bridge inspection and training of bridge inspectors.
According to those specifications, America’s infrastructure is beginning to show its age – and the bridges in Minnesota and North Dakota are no exception.
A deficient bridge has a major defect in its structure, as determined by an engineer.
Drivers take about 260 million trips over deficient bridges each day, according to the annual National Bridge Inventory. Laid end to end, the country’s deficient bridges would span from Washington, D.C., to Denver, Colo. — more than 1,500 miles.
According to the Federal Highway Administration, despite billions of dollars in federal, state and local funds being spent annually, 69,233 bridges — more than 11 percent of total highway bridges in the nation — are classified structurally deficient.
A structurally deficient bridge requires significant maintenance, rehabilitation or replacement. A state may restrict heavy vehicle traffic, conduct immediate repairs, or close the bridge until repairs can be completed.
Jamie Olson, an official for the North Dakota Department of Transportation, said a structurally deficient rating does not mean the bridge is unsafe or ready to collapse.
“What structurally deficient means is that either the deck, the superstructure or the substructure has a condition that warrants attention,” she said. “This can be as simple as a concrete bridge deck needing work or requiring a bridge deck overlay.”
Officials from both Minnesota and North Dakota DOT said any bridge deemed unsafe is closed immediately and either repaired or closed permanently.
According to the North Dakota Department of Transportation, as of September 2012, North Dakota had a total of 4,585 bridges, which include state, urban and county bridges. Of those, 17.9 percent fall into the structurally deficient and functionally obsolete category, ranking North Dakota about average compared with other states in the nation.
In Minnesota, one out of every 11 bridges that motorists cross each day are likely to be deteriorating to some degree. As of 2010, Minnesota had 13,068 highway bridges; 3,651 of them owned by the state; 9,312 owned by local counties, cities and towns; and 105 owned by other entities such as a private business or federal agencies.
Minnesota ranks 28th in the nation where the average bridge condition is worse than the statewide average of 8.8 percent. What this boils down to is that Minnesota has almost 2,900 bridges that are older than 50 years. Regardless of the amount of wear and tear experienced by a specific bridge, most bridges are designed to last roughly 50 years. What this means is that by 2030, the number of aging bridges will nearly double.
Transportation agencies would need $70.9 billion to overcome the current backlog of deficient bridges, according to the FHWA. Last year Congress passed legislation to eliminate the dedicated funds for bridge repair in the renewal of the federal transportation program.
Instead, states are directed to set repair standards. Now, bridge repair must compete with other transportation needs. In addition, the new law reduced access to funds for nearly 90 percent of structurally deficient bridges that are not part of the National Highway System (the interstate plus large state highways.)
Congress also reduced access to funding for the repair of most locally owned bridges, which are twice as likely to be structurally deficient as those on the state and federal systems, as well as state-owned bridges that are not designated as part of the National Highway System.
In 2008, Minnesota received $36 million in federal funds for bridge repair. Overall, the state $144 million on bridge upkeep and $205 million on new capacity.
Congress created the Federal Highway Bridge Program to fix and replace deficient bridges throughout the country, yet current funding is insufficient to keep up with the deterioration rate.
Addressing the issue
Some states, including North Dakota and Minnesota, are working to address the problem.
Both North Dakota and Minnesota DOTs have bridge inspection programs that inspect all bridges on a two-year inspection cycle.
Allowing bridges to slip into disrepair ultimately costs state and local governments billions more than the cost of regular, timely repair. Bridges provide crucial access between regions and cities, linking workers to jobs, goods to market and people to services.
Officials from both Minnesota and North Dakota Department of Transportation that motorists can be assured that bridges are safe for travel and all bridges follow a rigid comprehensive inspection program on an annual or biannual basis.
Of importance is the function of bridges. Not only do they serve as main routes for commuters, they also accommodate the transportation of goods and services. The principals of quality control in design and inspection are a new standard for all bridges across Minnesota and North Dakota.