On the morning of September 25, 2013, calls to 911 reported a sag in the deck of the Leo Frigo Bridge on the east side of the Fox River in Green Bay, Wisconsin. One of the support piers, Pier 22, had sunk approximately two feet overnight. The bridge was closed and an emergency investigation was launched to determine the cause of the settling.
Investigative activities included excavating around Pier 22 and other support structures, digging test pits, and collecting soil and groundwater samples in the area. GIS was used to record the locations of all these activities and display the spatial data produced by the investigation.
One of the earliest GIS applications in the investigation, was the analysis of historical aerial photography of the site. The photos were compared to identify changes in land use and drainage patterns as well as confirming the locations of fill. Because the analysis made use of readily available data from federal, state and county sources, the maps could be generated quickly and made available to the investigators.