Keywords: Trench safety - Fastening chains to raise trench box-2 (9250653062).jpg Image of workers attaching rigging hardware to the backhoe https //www flickr com/photos/niosh/9250653062/ Trench safety - Fastening chains to raise trench box-2 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 N03/9250653062 2015-04-23 18 51 11 United States Government Work Construction Safety Shoring Work Workplace National Institute for Occupational Safety and Health |