Investing in Transportation and Infrastructure

Installing Fiber Optic Sensors On Bridges To Monitor Bridge Stress Around The Clock

Recent technology advances, such as fiber optic sensors, allow for year around inspection on bridges that could prevent a catastrophic bridge failure like the tragic incident in Minneapolis. Currently, bridges are inspected every two years, approximately 90% of which are conducted visually.

Fiber optic sensors can be installed on spans and enable bridges to signal for help the moment structural problems arise. A series of sensors embedded in the bridge communicate wirelessly to a computer and provide engineers with a real time picture of a bridge’s health and safety so that problems can be acted upon immediately.

The sensors detect minute strains and changes in a bridge, leading to the immediate identification of cracks or weakening in the structure. In addition to identifying cracks, the sensors can detect the speed at which those cracks are spreading, identify the stress caused by heavy load and natural elements such as heat and wind, and also measure corrosive activity. The sensors don’t require batteries and would remain operational for many years.

According to a 2006 report by New York City, 84% of the City’s 19 largest bridge spans are in poor or fair condition. Despite spending $3 billion on bridge reconstruction over the last 8 years, the federal Department of Transportation has deemed 178 of the city’s bridges as structurally deficient, which signifies they’re in need of work but not in danger of imminent collapse.

While our city’s bridges are safe, decay from rust on steel gussets used in nearly all of the city’s steel bridges could eventually critically weaken supporting structures, and the cost to repair all the spans is prohibitive. As New York City and the nation face infrastructure maintenance costs that dwarf the amount of funds currently budgeted, sensor technology would provide invaluable information as to which bridges need repair first.

The cost of implementing this preventive technology is modest. For example, the installation of a fiber optic system on a 1000 foot span similar to the collapsed bridge in Minneapolis would have cost approximately $185,000. In contrast, the federal government directed over $250 million for the rebuilding of that bridge, with the final cost estimated up to $350 million. The cost of installing sensors on a larger span such as the Brooklyn Bridge is an estimated $250,000 to $500,000.

In August I announced the introduction of federal legislation to provide matching funds of 50% to cities and states that employ such technologies. To read the press release from the announcement event, click here

To read the text of my legislation, click here