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Volpe Center Highlights - March 2000

Focus

Director's Notes | Focus | Safety | Mobility | Human and Natural Environment |
Economic Growth and Trade | National Security

Volpe Acoustics Experts Study the Environmental Effects of Hovercraft on Fish and Wildlife in Alaska (USPA)

Could mail delivery in remote parts of Alaska be hurting fish and wildlife? The Volpe Center is supporting the U.S. Postal Service (USPS) by providing environmental services for a three-year demonstration program in which hovercraft are used to transport mail to remote villages in the vicinity of Bethel, Alaska. A comprehensive noise study of the British Hovercraft Corporation Model AP1-88 air cushion vehicle, the craft used for mail delivery, is part of a project being conducted by Dr. Paul Valihura of the Environmental Engineering Division to study the underwater effects of hovercraft operation on fish and wildlife.

The British Hovercraft Corporation Model AP1-88 air cushion vehicle delivers U.S. mail to remote villages in Alaska. (Photo courtesy of Dr. Paul Valihura)

The Alaska blackfish, Dallia pectoralis, are known for their tolerance to cold water and can survive for a few days after complete freezing of parts of the body, including the head. (Illustration courtesy of U.S. Fish and Wildlife Service)

From January 23 to 28, 2000, Mr. Christopher Roof of the Safety and Environmental Technology Division along with Mr. David Read of W. T. Chen and Mr. John Burgess, a biologist with CH2M Hill (both Volpe Center contractors), visited Bethel, Alaska, in order to perform noise measurements of the hovercraft and to study blackfish behavior near the small village of Kasigluk. Blackfish are a primary food source for the local population. The measurements were conducted while the Johnson River was covered with ice in order to evaluate the effects of ice on the underwater noise. In addition to conventional acoustic instrumentation, the team used hydrophones to measure underwater noise levels and specialized video equipment to monitor blackfish behavior. The team also monitored other environmental conditions, and interviewed local fishermen to obtain their day-to-day accounts.

Mr. Roof and his team accomplished their tasks despite numerous obstacles. Unexpected and unusual above-freezing temperatures caused the ice on the Johnson River to start melting. The state road, which is near the river and on which the team planned to travel by truck, had not been plowed. In addition, the team planned to stay in Kasigluk near where the testing would take place, but an electrical outage forced them to stay in Bethel and make the 30-mile trip each way every day to Kasigluk via snowmobiles.

A hydrophone measures noise levels under the ice on the Johnson River. (Photo courtesy of Mr. Chris Roof)

Sleds were used to transport more than 500 pounds of support equipment, including acoustic instrumentation for measurement in water and air, as well as meteorological and video instruments. One of Mr. Roof's biggest challenges was making certain that all of the electronic equipment worked despite low temperatures, wind, and vibrations from riding on the snowmobiles. Fortunately, extra backup equipment was brought along, as it was needed.

The final summary of the three-year ecological and noise monitoring project, The Final Ecological Monitoring Summary, was released on March 20, 2000. The winter underwater noise monitoring and visual observations showed that the hovercraft had little impact on blackfish subsistence gathering by the local Eskimos. It also showed that, after careful observation and repeated testing performed by Volpe staff over the past three years, the hovercraft has had little impact on waterfowl and only a few dead, injured, or stranded fish have been found.

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