As Canadian investigators sift through the remains of last Saturday’s Radiohead concert in Toronto, looking for clues as to why the stage collapsed before the show and killed the band’s drum technician, veteran concert producers are calling for fundamental industry changes. “You need to go to steel,” says Lars Brogaard, Rod Stewart’s production manager since 1985. “The shows nowadays are getting heavier and heavier with the lighting and the video screens. These aluminum roofs, they can’t take the weight.”