America’s infrastructure, once a symbol of national pride, is aging and poorly maintained. The years have taken their toll on steel and concrete, and the bridges, in particular, are on the verge of collapse.

Of the country’s total of 614,387 bridges, almost 4 out of 10 bridges are at least 50 years old. More than 20,000 are flagged as fracture critical—meaning if a critical component of the bridge gives way, the whole bridge collapses. More than 65,600 bridges are categorized as structurally deficient, and a further 7,795 bridges are tagged as structurally deficient and fracture critical—and considered to be in greater danger of collapsing. Despite these warnings, life goes on as usual, and 188 million trips on average are made across structurally deficient bridges every day. There appears to be little apprehension that so many accidents are just waiting to happen.

Real-Life Examples

The nation first became aware of how dilapidated its infrastructure is when the Silver Bridge between Virginia and Ohio caved in during rush hour on Dec. 15, 1967. Forty-six people died and two bodies were never recovered. The ensuing investigation determined that a crack in a single link led to the collapse. In addition to poor maintenance, the investigation also found there was an overload of stress on the bridge; on a daily basis, it was carrying traffic far heavier than its design permitted.

In 2011, a disaster was miraculously averted in Indiana when an enormous crack on a busy bridge was discovered in the nick of time. But, on May 24, 2013, a bridge north of Seattle collapsed when a truck crashed into it, sweeping away a number of vehicles.

The Frederick Douglass Memorial Bridge that was built in 1950 and leads into Washington, D.C., was neglected to a point of being beyond repair. The steel support was worn out, the bridge span was rusted and the concrete was crumbling. In August 2017, the D.C. Mayor Muriel E. Bowser unveiled the design for a replacement bridge.

Possible Solutions

When the imminence of collapse is not understood early, people suffer the consequences. Indeed, design flaws, material deterioration, fatigue, vibrations, foundation integrity issues and consistent loads and overloads on bridges weaken their serviceability and lifespan. Extreme weather conditions add to the problem. Intense heat warps concrete and steel, while salting of bridges in harsh winters will corrode steel.

Conventional technologies that have been used over the years will not expose these problems until it is too late to prevent a disaster. Many inspections are done using the naked eye or by using archaic methods such as pinging the bridge’s surface with a hammer or dragging a chain across the surface, listening for abnormal sounds.

On the other hand, technology now exists and allows the checking of concrete and steel for deterioration across the bridge deck.

Unmanned Aerial Systems (UAS) in drones also can easily access all areas of a bridge.

Conversely, antiquated manual methods require lane closures, night inspections to allow uninterrupted traffic flow and expensive equipment to access the under bridge. So, employing technology will actually trim costs and enable authorities to redirect more funds for repair and maintenance.

Bridge inspection guidelines have been revamped to strengthen early detection of issues, but the main inspection instrument, still, is visual inspection. Furthermore, federal records show many bridges go beyond the stipulated two years without safety inspections.

The existing system passes the buck from federal to state to local governments. Those who ultimately put the public at risk are not penalized, either. So it is business as usual, with antiquated methods, until the next catastrophe.

Over a decade ago, professionals were nonplussed as to why America is not deploying better technologies to inspect its aging infrastructure. Oral Buyukozturk, professor of civil and environmental engineering at the Massachusetts Institute of Technology, said, “We need to carefully evaluate and implement into our engineering and management practices the already existing high-tech methods for monitoring and testing bridges and other structures, and we must encourage the development of new technologies as needed.”

The safety of the public should be top priority and change must be initiated at federal, state and local levels of government. In addition, the “billable hours” system of awarding contracts must change—otherwise engineering firms will never use technology for inspection.