Posted on 10/31/2007 10:25:38 PM PDT by neverdem
COLTON, N.Y., Oct. 30 — The bridge that carries Route 56 over the Raquette River here is so ordinary that it has no name, only a number, 1027260. But for now it is a bridge like no other, studded with instruments like a cardiac patient, giving up secrets that may explain how to keep others from falling.
Bridges are big, dumb pieces of steel and concrete, and mostly out of mind, until one collapses, as the Interstate 35W bridge did in Minneapolis on Aug. 1. Even now, three months later, no one is sure why that happened, but it has focused the attention of engineers on techniques of bridge inspections, and how to diagnose their ills.
At this bridge, a two-lane, 360-foot steel and concrete affair built in the mid-1990s, “we are making the structure smart,” said Ratneshwar Jha, an associate professor of mechanical engineering at nearby Clarkson University.
The Route 56 bridge in far upstate New York has been fitted with 60 wireless sensors that will measure movement, strain and temperature, as a way to judge its structural health.
Engineers have used sensors for years, and lately have tried out wireless sensors, which permit easier readings and, potentially, lower costs. But this $900,000 project, mostly paid for by the New York State Energy Research and Development Authority, is unusual for its scope.
The Minneapolis bridge collapse could have been caused by a problem in inspection, but also by problems in design, construction or maintenance.
A few theories have emerged. It was unusually warm at the time, and one area of investigation involves whether the joints that allow the bridge deck to expand were operating properly. In addition, many pieces of construction equipment and nearly 100 tons of gravel were on the bridge at the time of the collapse, according...
(Excerpt) Read more at nytimes.com ...
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