5 Things: Bridges

1. Inspections

Bridge inspectors across the U.S. were out in force Thursday. Bridges of all types received visual inspections - but especially those that are steel truss bridges, the kind that the Interstate 35W bridge was. Illinois wouldn't identify its steel truss bridges, but the state has them. Missouri's Hurricane Deck Bridge - similar to the 1-35W one - got a check-up, as did bridges throughout New England.

2. 'Structurally deficient'

More than a few bridges in use are "structurally deficient," the same designation given to the Minneapolis span before it collapsed. Illinois said 9.4 percent of its bridges are deficient, while Massachusetts identified 9 percent as deficient.

3. Weather damage

Bridges in cold-weather states face wear down faster. According to John Harms, senior vice president of Hanson Professional Services, a nationally known engineering firm based in Springfield, Ill., salt spray and cycles of freezing and thawing can contribute to deterioration. "Salt is detrimental to steel. It gets into … the reinforcement bars and cause them to rust," Harms said.

4. It's expensive

Maintaining transportation systems isn't cheap. A report released in March from the Massachusetts Transportation Finance Commission said maintaining the state's transportation system over the next 20 years will cost $15 billion to $19 billion more than what will be available under current financing plans. Those projections don't include new projects.

5. Stay calm

Despite the horrifying bridge collapse, motorists should remain calm and carry on as usual, officials said. "We don't want ... motorists and residents who are out on the roadways and crossing bridges in their vehicles to panic," said Illinois Department of Transportation spokeswoman Marisa Kollias. "We have a team that is diligently working to double- and triple-check dozens of bridges across the state.