Somebody missed a couple decimals while calculating load.
Sounds similar to another bridge collapse many years back.....maybe 20??
The I-35 bridge in Minnesota collapsed in 2007 (original design flaw (which held up for 40 years though)); a new pedestrian walkway within the Kansas City Hyatt collapsed on its first evening of use in 1981 (construction mistake). Those are the ones that come to mind immediately.
https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge
https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse