Investigators are reportedly looking at whether rusted plates may been a factor in the collapse of the I-35-W bridge in Minneapolis. The Star Tribune is also reporting that the National Transportation Safety Board is considering heat as a possible factor in the collapse. Linda Figg is the head designer of the replacement span. She says the new bridge will be built with expansion joints that can withstand Minnesota's hot summers and cold winters. Figg says designers will use that latest technology in order to build a state of the art bridge.