Keywords: Trench safety - ladder (9247869061).jpg Image demonstrating to always have a ladder in the trench while working https //www flickr com/photos/niosh/9247869061/ Trench safety - ladder 2010-03-16 11 42 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 N03/9247869061 2015-04-23 18 50 30 United States Government Work Construction Safety Shoring Work Workplace National Institute for Occupational Safety and Health |