The New Tappan Zee Bridge’s Smart Technology Makes It Built To Last

One of the most technologically advanced bridges in the U.S. opened to traffic shortly after 1:30 a.m. on Saturday, August 26, partially replacing the old Tappan Zee Bridge, New York State’s longest bridge.

The Gov. Mario M. Cuomo Bridge is on schedule to replace the entire Tappan Zee Bridge when its second span is completed later this year. Once both spans are open for traffic, the new bridge will have eight lanes, including four for breakdowns and emergencies, bicycle and walking paths, and a future mass transit crossing. ENR reported in its March 20/27 issue that the new $3.98 billion bridge is designed to use smart technology systems to keep it operating smoothly and safely for the next 100 years—without needing any major repairs.

The New York State Thruway Authority (NYSTA), which owns and maintains both the soon-to-be-demolished Tappan Zee Bridge and the new Gov. Mario M. Cuomo Bridge, is using built-in measuring, gauging, monitoring and reporting sensors, as well as drones for safety and security monitoring, to handle the increasing number of vehicles expected to cross the new bridge, including future bus rapid transit and a commuter rail service.

Originally completed in 1955, the Tappan Zee Bridge crosses the Hudson River at its second-widest point, 25 miles north of New York City, connecting Tarrytown and South Nyack. The Gov. Mario M. Cuomo Bridge, a twin-towered, cable-stay bridge with four lanes in each of its two spans, was designed to last twice as long as its predecessor. Toward that end, it was designed with a dozen types of built-in sensors to warn its operators of potential strains, forces, conditions or problems that could affect its structure or safety.

For example, the monitors can detect heavy winds and help the operations team decide whether to restrict trucks from using the bridge. They can inform bridge operators if something is wrong with any of the bridge’s piers, decks, girders, stay cables, bearings or roadways, which will help extend its longevity by alerting crews to any structural problems before they become extreme or, in some cases, even visible.

As of March, at least 450 sensors were installed on the new bridge to monitor:

  • Angular movement (tower sway and alignment)
  • Cable force (the tension present on each strand)
  • Corrosion (material quality and composition)
  • Stress/deformation (potential long-term distortions)
  • Cable temperature (climate impacts)
  • Wind conditions (speed and direction)
  • GPS receiver data from the towers and bridge deck (to measure the mode shapes, or displacement patterns, of the structure)
  • Weather station data (air pressure, humidity and climate)
  • Structural vibrations (effects of traffic weight on roadways)
  • Lighting (status of each LED fixture)
  • Navigation lights (guiding marine and aerial traffic)
  • Traffic (vehicle speed and volume)

The monitors will send a constant flow of data to NYSTA’s command center, where it will be used to compile customized reports or trigger warnings for specified data readings.

While its high-tech components may need to be replaced or upgraded for maintenance, the new bridge will hopefully have a life span of 100 years, thanks in no small part to the smart technology that’s there to prevent any major structural damage or incidents that could shorten it.

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Photos and video courtesy of the New York State Thruway Authority

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