Keywords: Trench safety - Fastening chains to raise trench box (9247870523).jpg Workers attaching rigging hardware to the backhoe https //www flickr com/photos/niosh/9247870523/ Trench safety - Fastening chains to raise trench box 2010-03-16 11 55 https //www flickr com/people/25069384 N03 National Institute for Occupational Safety and Health NIOSH from USA PD-USGov NIOSH http //flickr com/photos/25069384 N03/9247870523 2015-04-23 18 50 12 United States Government Work Construction Safety Shoring Work Workplace National Institute for Occupational Safety and Health |