Aug. 2, 2007 -- The fallen I-35 West bridge that connected the east neighborhood of Minneapolis with the University of Minnesota's west neighborhood was investigated in 2005 and 2006 and had no structural defects, according to Minnesota Gov. Tim Pawlenty.
However, construction that was reportedly in progress restricted traffic to one lane.
The I-35 West bridge was built in 1967 — it has eight lanes of traffic, sits 64 feet above the water and has the highest daily traffic flow in the state.
The bridge was built with a single 458-foot-long steel arch to avoid putting any piers in the water that might impede river navigation.
So, how did this catastrophe, which has since left seven people dead and dozens more injured, happen?
Highway engineers say the neglect of America's infrastructure costs lives every day. More than 40,000 people die in highway accidents each year.
Road conditions, the engineers say, are a factor in almost one-third of those deaths.
America's most important road system — 46,000 miles of interstate highway — is now half a century old.
A report card two years ago from the American Society of Civil Engineers said that 34 percent of major roads are in poor or mediocre condition.
And that's not all.
The civil engineers say the number of unsafe dams has risen by more than 33 percent in the past two years, and in that time, there have been 29 dam failures.
Power capacity isn't keeping pace with demand, and the power grid needs $10 billion a year invested over the next five years.
And, according to civil engineers, 27 percent of U.S. bridges are structurally deficient.
Pete Ruane, of the American Road Builders' Association, said, "Many of these bridges — their life cycle, their life expectancy, and depending on the state — many of them are in very, very bad shape, and need major maintenance or replacement."
The Department of Transportation National Bridge Inventory Web site reported the I-35 West bridge's condition as fair. Its overall bridge rating "meets currently acceptable standards."
But, according to a technical report evaluated by the University of Minnesota civil engineering department, in March 2001, the bridge's deck truss experienced "fatigued cracking" and has many "poor fatigue details" on the main truss and floor truss system.
"But that will cost an estimated $10 billion each year over the next two decades," Ruane said, "but that's small compared to the estimated $54 billion poor roads cost motorists in repairs and extra operating costs."
Some argue the real problem is congestion — that the road system is strained beyond its capacity.
With Americans already losing $3.5 billion a year, the situation threatens to go from slow to slower.
Just a few months ago, in Oakland, Calif., a tanker truck carrying 8,600 gallons of gasoline crashed into a highway support on the highway interchange known as "the maze." Flames from the accident burned with such intensity, they melted the steel supporting the roadway above, causing it to collapse.
That collapse is expected to disrupt traffic for months, as nearly 300,000 commuters rely on the damaged stretch of road each week.
Traffic is an increasing source of stress to commuters in this country, and highway reconstruction is a major cause of it. But knowing that the construction could save lives should ease the pain at the wheel.
ABC's Bob Jamieson contributed to this report.