A trench cut open along its length, drawn 50 feet long and 8 feet wide, on a bench base. The near wall is cut away so you can see in. A steel tape with a plumb bob hangs from a boom and reaches the trench floor, and a window on its reel reads the depth in feet. The ground stays level and the floor lowers as the depth goes up, from 0 to 22 feet. From 4 feet a ladder stands against the far wall and a tape on the floor is marked out to 25 feet each way. From 5 feet two pairs of aluminum hydraulic shoring uprights with cross braces stand in the trench. A windrow of spoil lies behind a 2 foot keep-out strip at the trench edge.

A 50 ft trench, drawn 8 ft wide, with the near wall cut away so you can see in.

At 5 ft or more, each employee in the trench must be protected from cave-ins by an adequate protective system, unless the trench is cut entirely in stable rock. Hydraulic shoring is drawn. Sloping, benching and shields are other systems the rule covers. The way out is still required.