Federal officials arrive in the Twin Cities today (Thursday) to investigate the collapse of the eight-lane I-35W bridge in Minneapolis. The National Transportation Safety Board says it's sending a team of investigators to accompany the board's chairman. Governor Tim Pawlenty says two state inspections in the past two years found no structural problems with the bridge that collapsed. Minnesota Public Radio's Elizabeth Stawicki reports: {The 40-year-old bridge was considered a bit of a marvel when in 2001 it became the first of its kind in the U.S. to be equipped with an anti-icing system. A computerized system sprayed an anti-icing chemical based on sensors that collected data on pavement temperature, ice and moisture. About 140-thousand vehicles traveled over the bridge each day.