Equipment World recently posted an interesting article about the structural deficient and fraction critical bridges here in the United States.
The difference between the two are explained here:
- Structurally Deficient: bridges in need of repair and or replacing because of component deterioration
- Fraction Critical: bridges at risk of collapse if one vital component fails
The average lifespan for a bridge is typically 50 years. There are many bridges that are currently exceeding their lifespans with no sight of updates due to funding restrictions. This is going to cause a growing concern for tragedies like the bridge collapse in Washington in May of this year.
The bridge was built in 1955 and has a sufficiency rating of 57.4 out of 100, according to federal records. That is well below the statewide average rating of 80, according to an Associated Press analysis of federal data, but 759 bridges in the state have a lower sufficiency score.
According to a 2012 Skagit County Public Works Department report, 42 of the county’s 108 bridges are 50 years or older. The document says eight of the bridges are more than 70 years old and two are over 80.
Washington state was given a C in the American Society of Civil Engineers’ 2013 infrastructure report card and a C- when it came to the state’s bridges. The group said more than a quarter of Washington’s 7,840 bridges are considered structurally deficient of functionally obsolete.