On the third anniversary of the collapse of the I-35W bridge in Minneapolis,
CNN takes a look at its high-tech replacement:
"The new bridge, completed in September 2008, is expected to stand for 100 years.
"Three-hundred-twenty-three high-technology sensors dot the structure, spitting out a constant stream of data regularly analyzed by engineers at nearby University of Minnesota.
"At a total cost of about $1 million including wire connections and power sources, the sensors don't eliminate the need for visual inspections, but they do provide an extra layer of maintenance security.
"The sensors monitor corrosion, stress and the movement of the bridge from the constant traffic.
"'The fiber-optic strain gauge technology is fairly cutting edge,' said Phipps. 'A tiny beam of light is used to measure very small differences in the movement of the bridge when vehicles pass over.'"
Read the full article
here.