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Preventing worker deaths from trench cave-ins (supersedes 2011-180).

Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2011-208, 2011 Sep; :1-4
Workers are at risk of death from cave-ins during trenching and excavation activities. NIOSH recommends engineering controls, protective equipment, and safe work practices to minimize hazards for workers. Workers who dig or excavate trenches are at risk of death if they enter an unprotected trench and the walls collapse. However, hazards associated with trench work and excavation are well defined and preventable. The OSHA standard for excavation and trenching, known as 29 CFR* 1926 Subpart P, describes the precautions needed for safe excavation work. There is no reliable warning when a trench fails. The walls can collapse suddenly, and workers will not have time to move out of the way. Even though small amounts of dirt may not seem treacherous, a single cubic yard of dirt can weigh more than 3,000 pounds, which can fatally crush or suffocate workers [Deatherage et al. 2004]. Even small, solid pieces of dirt can cause serious injuries. From 2000-2009, 350 workers died in trenching or excavation cave-ins-an average of 35 fatalities per year [BLS 2010]. Most incidents involve excavation work or "water, sewer, pipeline, and communications and power-line construction" [CDC 2004]. An analysis of OSHA data from 1997-2001 showed that 64% of fatalities in trenches occurred at depths of less than 10 feet [Arboleda and Abraham 2004]. Lack of a protective system was the leading cause of trench-related fatalities in a review of OSHA inspections [Deatherage et al. 2004]. OSHA requires that all excavations 5 feet deep or greater make use of one of the following protective system options (see Figure 1): (1) sloping the ground; (2) benching the ground;† (3) shoring the trench with supports such as planking or hydraulic jacks, or (4) shielding the trench (using a trench box). Workers should never enter a trench that does not have a protective system in place designed and installed by a competent person. Factors such as type of soil, water content of soil, environmental conditions, proximity to previously backfilled excavations, weight of heavy equipment or tools, and vibrations from machines and motor vehicles can greatly affect soil stability and the hazards that workers face. When the sides of trenches are shored, the type of soil and width and depth of the trench affect how far apart the supports should be spaced. Different OSHA regulations apply to the different types of supports used for shoring. Consult 29 CFR 1926 Subpart P Appendices C and D for more information. Appendix F provides a flow diagram for making decisions. Section V, Chapter 2 of the OSHA Technical Manual provides a guide on recognizing and preventing trenching and shoring hazards.
Construction; Construction-workers; Excavation-equipment; Ground-control; Ground-stability; Mortality-data; Mortality-rates; Regulations; Engineering-controls; Environmental-control-equipment; Personal-protective-equipment; Work-practices; Work-environment; Safety-measures; Safety-practices; Injury-prevention; Occupational-hazards; Industrial-engineering; Industrial-hazards; Case-studies
Publication Date
Document Type
Numbered Publication; Workplace Solutions
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
DHHS (NIOSH) Publication No. 2011-208; B10122011
NIOSH Division
Priority Area
Source Name
National Institute for Occupational Safety and Health
Page last reviewed: November 6, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division