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GCN : January and February 2017
BY PATRICK MARSHALL EMERGING TECH ACCORDING TO ERIN BELL, the project to transform New Hampshire’s Memorial Bridge over the Piscataqua River into a self-diagnos- ing, self-reporting “smart bridge” resulted from a for- tuitous sequence of events. Bell, an associate profes- sor of civil and environ- mental engineering at the University of New Hamp- shire, said a colleague in the School of Marine Sci- ence and Ocean Engineer- ing came to her in 2013 with the idea of conducting a three-month test before the bridge was torn down to make way for a new structure. The plan was to attach an underwater tur- bine to the old bridge that would generate electricity from the tidal motion of the river. As she began making inquiries, Bell was surprised when the contractor build- ing the replacement bridge asked whether the turbine could instead be sited on the new vertical-lift bridge for long-term deployment. “So that’s where the project started,” she said. Part of her work involves using sensors for structural monitoring. “We would put sensors on the girders to make sure we are not over- stressing [the bridge],” she said. Then it occurred to the team that they could power the sensors with electric- ity generated by the tidal turbine. Bell received a grant from the National Science Foun- dation’s Partnerships for Innovation program, which led to further expansion of the project. The New Hamp- shire Department of Trans- portation also awarded the team $400,000 to expand the sensor network. Now the team is prepar- ing to install a suite of sen- sors, including accelerom- eters, tilt meters and “strain brevets” that measure pressure. All the sensors are wired to a node that trans- mits the data via Bluetooth to a hub. The team is also installing environmental sensors to monitor water quality — including salinity, turbidity and temperature — and an acoustic Doppler current profiler to collect data about water flows. Finally, the researchers will install a weather station on the bridge to monitor temperature and humid- ity because engineers have found that those factors influence the effect of high winds on such structures. “There are a lot of things we will learn about the future of bridge design,” Bell said. The team’s find- ings might also help bridge managers make better deci- sions about maintenance and daily operations, such as raising a span to let ship- ping traffic sail underneath. They will know “when they shouldn’t lift rather than just saying, ‘I think it’s too windy so we’re not going to do a lift today.’” The three-meter-wide tidal turbine will power not only the sensors but also the bridge’s lights, with the goal of making the infra- structure independent of the electricity grid. The idea was spawned by Hurricane Sandy, which disrupted ac- cess to fuel and electricity, Bell said. Although the single turbine doesn’t gener- ate enough power to lift the span on the Memorial Bridge, the project is only a demonstration of the con- cept. “When new bridges are built, perhaps a larger array of these turbines can be integrated so the bridge will no longer be grid- dependent,” she said. Bell views the Living Bridge project as part of a paradigm shift toward integrating technologies and disciplines to make infrastructure smarter. “The idea was to make the bridge a living laboratory, some- thing that students from kindergarten to Ph.D. candi- dates could learn from,” she said. • ‘Living bridge’ pioneers smart infrastructure Underwater turbines power sensors that monitor the structure and environmental conditions around the Memorial Bridge in New Hampshire. 12 GCN JANUARY/FEBRUARY 2017 • GCN.COM NH.GOV/DOT 0217gcn_012.indd 12 1/31/17 1:42 PM
October and November 2016