Michael Barker said that, based on computerized testing he s developed over the past year, many small bridges are conservatively posted a fact known and discussed by truck operators and other highway engineers for years.
Low weight limits cause trucks and school buses to make long detours around the bridges.
Mr. Barker said his system, using sensors, lasers, computers and other devices to measure and record bridge deflections, can prove that bridges can safely take higher loads. Part of the justification for raising load limits on four smaller bridges he tested is strength added by curbs and railings. Deflection, along with lateral and longitudinal weight distribution, are among the eight factors measured and recorded by his system. It can take as little as 90 minutes to run a deflection test on a bridge. It begins with attaching strain gauges on the girders and setting up laser drives.