SEATTLE - Thousands of bridges around the U.S. may be one freak accident or mistake away from collapse, even if the spans are deemed structurally sound.

Bridge regulators call the more risky spans "fracture critical," meaning that if a single, vital component of the bridge is compromised, it can crumple.

Fracture critical bridges, like the I-5 span in Washington, are the result of Congress trying to cut corners to save money rather than a lack of engineering know-how, said Barry B. LePatner, a New York real estate attorney and author of "Too Big to Fall: America's Failing Infrastructure and the Way Forward."