How safe are area bridges?
A report released Friday by MnDOT indicates several lakes area bridges are rated structurally deficient or functionally obsolete.
However, bridges found to be in poor condition are still safe to use.
MnDOT officials reported Thursday that about 8 percent of all bridges in the state, including the I-35W bridge, have been listed by the federal government as "structurally deficient," compared to 12 percent nationally. Bridges that have a sufficiency rating less than 80 are considered to be structurally deficient. The I-35W bridge over the Mississippi River that collapsed Wednesday had a sufficiency rating of 50.
This was the view Saturday morning of the Washington Street bridge (Highway 210) over the Mississippi looking north from the Laurel Street Bridge. The 210 bridge is on a MnDOT list as functionally obsolete.
Brainerd Dispatch/Kelly Humphrey
A bridge is typically judged structurally deficient if heavy trucks are banned or there are other weight restrictions. Under these circumstances, the bridges are considered in need of substantial maintenance, rehabilitation or even replacement.
Area bridges that made this MnDOT deficiency list include the following:
- AITKIN COUNTY: U.S. 169 bridge crossing the Ripple River is considered structurally deficient. The bridge was built in 1964 and has an average daily traffic count of 3,950 vehicles. Sufficiency rating is 58.1. Its last inspection was Nov. 21, 2006.
- CASS COUNTY: Trunk Highway 84 bridge crossing Norway Brook (Dam) is considered functionally obsolete. The bridge was built in 1943 and has an average daily traffic count of 3,850 vehicles. Sufficiency rating is 63.5. Its last inspection was Nov. 21, 2005.
- CROW WING COUNTY: Trunk Highway 210 bridge crossing the Mississippi River is considered functionally obsolete. The bridge was built in 1932 and has an average daily traffic count of 26,000 vehicles. Sufficiency rating is 64.3. Load limits are posted. Its last inspection was Aug. 10, 2005.
- MILLE LACS COUNTY: Trunk Highway 169 bridge and the Trunk Highway 23 bridge both crossing the Rum River are considered to be functionally obsolete. TH 169 bridge was built in 1951 and has an average daily traffic count of 11,000 vehicles. Sufficiency rating is 51.4. Load limits are posted. Its last inspection was Oct. 19, 2006. The TH 23 bridge was built in 1953 and has an average daily traffic count of 8,300 vehicles. Sufficiency rating is 47.5. Its last inspection was Oct. 27, 2006.
- MORRISON COUNTY: Trunk Highway 238 bridge crossing Pike Creek and Trunk Highway 27 bridge crossing Platte River are both considered to be functionally obsolete. TH 238 bridge was built in 1924 and has an average daily traffic count of 2,250 vehicles. Sufficiency rating is 68.2. Its last inspection was Oct. 3, 2006. TH 27 bridge was built in 1940 and has an average daily traffic count of 2,800 vehicles. Sufficiency rating is 47.2. Its last inspection was Aug. 12, 2005.
Although more than 70,000 bridges nationwide are rated structurally deficient, a top transportation official Friday called the deadly collapse of the I-35W bridge an "anomaly" and said motorists shouldn't fear for their safety. National Transportation Safety Board Chairman Mark Rosenker said while visiting the I-35W bridge wreckage Friday that rules in place for the past 30 years have improved bridge conditions and standards.
According to the American Society of Civil Engineers, repairing all bridges rated structurally deficient would take at least a generation and cost more than $188 billion - at least $9.4 billion a year over 20 years.
This story contains information provided by The Associated Press.