Old photos show flaws in steel of I-35W bridge

Did these flaws cause the collapse? Beats me - I'm no engineer. However, that article prompted me to click on to a fascinating retrospective called "13 Seconds in August" regarding the collapse of the same bridge. A long post-collapse photo is provided with a number next to each vehicle which fell with the bridge. By clicking on each car or truck, you can see a biography of the vehicle's occupants where it is known, and in some cases, video interviews with the survivors.