Unmanned Boats to Inspect Bridges

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By Dale King The Pineapple Contributing Writer The task of inspecting and maintaining Florida’s network of some 11,450 bridges is an arduous one, especially because so many span rivers, canals and saltwater areas. Researchers in the College of Engineering and Computer Science at Florida Atlantic University have received a one-year, $187,000 grant from the Florida Department of Transportation (FDOT) to develop unmanned marine vehicles for on-water bridge inspections. Unlike manned vessels, which are continuously operated by human users, unmanned surface vehicles or USVs can run autonomously without human intervention for prolonged periods. “Technological solutions that can help make the bridge inspection process less costly, more efficient and safer for personnel are vital,” said Mohammad Ilyas, Ph.D., dean of FAU’s College of Engineering and Computer Science. “Although 25 percent of bridges in the U.S. are considered deficient or obsolete, Florida is among the lowest nationally in terms of the percentage of bridges considered structurally deficient.” He did note that bridges crossing warm seawater are especially susceptible to corrosion. The particularly vulnerable area, called the “splashzone,” is the section of a bridge piling or support structure at the water’s surface where seawater repeatedly splashes and then evaporates, leaving behind a thin residue of concentrated salt. The salt diffuses into bridge pilings and can quickly cause steel portions of the structure to corrode. Currently, FDOT inspects each of the 11,450 bridges at least once every two years, and more often when required due to age or structural concern. “The inspection of bridge pilings at the waterline and underwater can be difficult,” said Karl von Ellenrieder, Ph.D., principal investigator of the grant, professor in the Department of Ocean and Mechanical Engineering and associate director of the SeaTech Institute for Ocean Systems Engineering at FAU. “Fast flowing tidal currents, waves, strong coastal winds and the presence of wildlife are common environmental factors that can make water-based bridge inspections difficult and sometimes dangerous for personnel.” “In recent years, USVs have been used more often in many applications, including ocean sampling, maritime search and rescue, hydrologic surveys, harbor surveillance and defense,” said von Ellenrieder. “From a design standpoint, one of the main advantages USVs have over manned vessels is that their configuration does not need to accommodate the space and safety requirements of human operators,” said von Ellenrieder. “Because of this, USV design can be more highly optimized according to sensing, maneuvering or deployment needs.” Von Ellenrieder and his team will provide recommendations to the FDOT on how USVs can be best used to conduct or assist bridge inspections. As part of the project, several on-water, proof-of-concept, USV-based bridge inspection demonstrations will be conducted in collaboration with the Gulf Unmanned Systems Center of Carrabelle, Fla., at sites in northern Florida using a USV developed at FAU.