"Engineers are watching -- trying to ensure the public safety," said Herrmann, a former president of the American Society of Civil Engineers who has spent 40 years designing and maintaining bridges.
"If you look at the Champlain Bridge in New York state, they were watching that bridge very carefully and when it got to the point where the deterioration was suddenly accelerating, they decided to close it immediately."
The bridge, which linked Crown Point, New York, with Chimney Point, Vermont, was demolished in 2009 and a newly built bridge opened to traffic in 2011.
In some instances, the new generation of bridges that are being built today include new monitoring technology instead of relying solely on bridge inspectors.
When the I-35W bridge collapsed in Minneapolis in 2007, 13 people died and 145 others were hurt. The bridge that replaced it cost $233.8 million. Out of that budget, about $1 million paid for smart technology that senses danger and warns of a potential structural threat.
Sensors were built into the bridge to monitor corrosion, stress and the movement of the structure from constant traffic.
A tiny beam of light is used to measure very small differences in the movement of the bridge when vehicles pass over. Data from the sensors is monitored, providing an extra layer of engineering oversight.
"We want these bridges to be safe," said Herrmann. "But we need to provide the funding, the investment to make them safe."
The number of America's deficient bridges has actually decreased "ever so slightly over the last couple of years," Herrmann said. That's mostly because of increased funding from state and local governments, he said.
Is that a good sign?
Herrmann said yes, but he added, "If we don't start accelerating we could start losing ground."