Airborne: Rhode Island Highway Project Incorporates New Survey Technique
By Bret Hazell

A recent project to relocate a portion of Interstate 195 in Providence, R.I. involved a new aerial survey technique that may be best recognized for what it didn't do: put highway workers' lives at risk and snarl traffic for weeks.
      The unique survey also saved taxpayers money in traffic-control costs by putting fewer highway personnel on the ground, and saved commuters time by not closing lanes on the heavily traveled freeway.
      "Our contacts with the Rhode Island project have told us that they're seeing an approximate savings of $100,000, not including the incalculable savings related to keeping all the travel lanes open," said Richard Davis, president of the Richard B. Davis Co. Inc. aerial survey firm of Smith River, Calif.
      If conventional ground-surveying methods had been used on I-195, lane closures and significant traffic control would have been required for weeks, with major traffic delays possibly occurring, Davis said. The aerial survey required no lane closures and only minimal traffic control on the road's shoulders, thus greatly reducing traffic-control costs, dangers and driver frustration.
      Working with the Rhode Island firms of Maguire Group and Bryant Associates - contractors for design and engineering - Rhode Island's Department of Transportation is the nation's first highway office to survey a major freeway using Richard B. Davis Co.'s technique of Low Altitude Mapping Photogrammetry (LAMP).
      LAMP involves the use of sophisticated camera equipment mounted in a small helicopter, which makes low-altitude passes over the survey area. This allows close-range photographs of pre-placed ground targets within the desired project site. Using complex photogrammetric and computer processing techniques, survey data is extracted from the photographs with a by-product being the photos themselves, something ground surveys don't produce.
      The benefits: The helicopter can photograph the survey area quickly, efficiently and without putting people on the highway - a vital safety feature on a thoroughfare like Interstate 195, which bears an estimated 160,000 vehicles per day.
      "All it takes is one inattentive or careless driver to imperil the lives of ground surveyors," said Davis, adding that "highway work is among the nation's most deadly occupations."
      Survey accuracy is another major benefit of the LAMP process, according to Davis. Because the helicopter can legally fly lower and slower than airplanes, it provides more accurate readings than those obtainable by fixed-wing aircraft which must remain at or above 1,000 feet. Using the LAMP method, measurements on I-195 were obtained to less than 3/100th of a foot. More precise accuracy can be obtained if situations require it.
      Four other highway jobs in the Rhode Island and Boston areas are being negotiated as a result of the early results from the I-195 project, Davis said.
      In addition to keeping cars moving in Rhode Island, Richard B. Davis Co. has been called upon to keep airplanes flying at Portland International Airport in Oregon, where the firm teamed with Spencer Gross Inc. of Portland in conducting an aerial survey of the main runway and taxiways. The survey technique allowed the airport to function without affecting air traffic, thereby eliminating the possible disruption of passenger flights.
      Richard B. Davis Co. first developed LAMP to monitor coastal jetties for the U.S. Army Corps of Engineers. Through periodic high-precision surveying, the Corps can monitor jetties for early signs of storm-caused damage. Once identified, jetties can be repaired before damage worsens and repair costs escalate.
      It was a jetty survey in the Bering Sea, in the remote Pribilof Islands of Alaska, which earned the company the 1994 National Society of Professional Surveyors' "Most Interesting Surveying Project of the Year Award" on March 1 at the society's annual convention in Charlotte, N.C.
      For this project, the helicopter was flown in a cargo plane from Anchorage to the islands. Utilizing LAMP technology, the helicopter surveyed the 1,800-foot-long jetty which guards the fishing community of St. Paul from furious Bering Sea storms.
      Davis believes the market for LAMP technology is significant, and that as the technique becomes more accepted and known, more projects and people will benefit from its advantages.

About the author:
Bret Hazell serves as general manager for Richard B. Davis Co. Inc. in Smith River, Calif. He can be reached at 707-487-6277.

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