Earthmoving/ trenching construction, safety: Caterpillar 320CL track mounted hydraulic excavator/backhoe excavates a bucket of soil inside trench shield/box. Trench shield extends from bottom of trench to above top of excavation and protects the workers inside it from possible trench wall cavein. Backhoe bucket is sized to fit interior width of shield. Primary excation was by this same backhoe using a wider, larger bucket. Bucket has picked up soil from bottom and is now raising it up to dump into excavation outside the shield. First Street, Ann Arbor, Michigan 2006.
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