Trends Spring 2016 - Page 7

Studying Streambank Stabilization Research team studies options, makes science-backed recommendations By Tawny Quast W hen it comes to stabilizing a stream or river bank, two basic schools of thought exist: using a “hard” engineered approach of rocks, concrete blocks, and other man- made materials to protect the bank; or using the “soft” environmentally sensitive approach of vegetation and natural material. However, the answer to what’s the best way to protect a bank isn’t so basic, with many opinions about what techniques work best under what circumstances. A combination of these two approaches, often called “biotechnical streambank protection,” may in many cases offer an optimal solution. Essentially, keeping a highway safe from an unstable bank is a serious matter, with people’s lives at risk if a structure such as a bridge were to fail. And to an engineer responsible for designing streambank protection measures, mere opinions of what works aren’t good enough. ABOUT THE TRANSPORTATION RESEARCH BOARD The Transportation Research Board (TRB) is one of six major divisions of the National Research Council. The mission of the TRB is to provide leadership in transportation innovation and progress through research and information exchange. The Board’s activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia. The program is supported by state transportation departments and federal agencies. For more information, see Credit: “You need to emphasize good solid engineering when it comes to streambank stabilization,” explained Pete Lagasse, senior hydraulic engineer at Ayres Associates. “The problem with just using vegetation (to protect a bank) has been that there was little quantitative information out there to give an engineer the confidence to stand behind that design.” STUDY GOALS OUTLINED Which is exactly why the National Cooperative Highway Research Program (NCHRP) embarked on a study aimed at backing the design and installation of streambank protection measures with solid, quantifiable research. NCHRP is a forum for coordinated and collaborative research administered by the National Academy of Science’s Transportation Research Board in cooperation with the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway