Alternatives to Timber Shoring

Aluminum hydraulic shoring is an acceptable alternative to timber shoring when it is selected, installed, and used in accordance with the system ratings and a competent person’s evaluation.

• Aluminum hydraulic shores are typically used to provide vertical and lateral support in trenches where lightweight, adjustable systems are advantageous.
• The system must be sized for the trench depth and soil conditions and installed per the manufacturer’s instructions.
• A competent person must inspect conditions and confirm the system’s capacity before allowing workers in the trench.

See the guidance on alternatives to timber shoring in Appendix E to Subpart P (Alternatives to Timber Shoring) for more detail.

Yes — pneumatic and hydraulic shores are permitted alternatives to timber shoring when they are properly designed, installed, and evaluated by a competent person.

• These systems provide adjustable pressure against trench walls to limit cave-ins and are commonly used where rapid installation or frequent adjustment is needed.
• They must be used according to the manufacturer’s ratings and instructions, and their capacity must match the soil type and trench depth.
• The competent person must inspect them daily and after any event (rain, vibration, strike) that could change trench conditions.

Refer to Appendix E to Subpart P (Alternatives to Timber Shoring) for the acceptable use of pneumatic/hydraulic shoring.

A trench shield (trench box) is a protective structure placed in a trench to protect workers by providing a space of safety if a collapse occurs, but it does not prevent soil from failing.

• Shields are designed to withstand loads from cave-ins and be large enough to protect workers inside the shielded area.
• They protect occupants from soil that collapses onto the shield but do not shore up the trench walls—so placement and sizing must suit the job.
• The competent person must determine whether a shield is appropriate for the soil conditions and trench depth, and installation must follow the manufacturer’s instructions.

See Appendix E to Subpart P (Alternatives to Timber Shoring) for guidance on using trench shields.

Yes — trench shields can be used instead of sloping or benching as an acceptable protective system when they are appropriate for the soil and trench conditions and are installed properly.

• Shields provide a safe working space inside the trench, whereas sloping/benching reduce the angle of the trench walls to prevent collapse.
• Selection depends on site constraints, depth, soil type, utilities, and access needs; the competent person must choose the system that gives adequate protection.
• If a shield is used, it must be sized and positioned correctly and inspected regularly.

Consult Appendix E to Subpart P (Alternatives to Timber Shoring) to determine when a trench shield is an acceptable alternative.

Trench jacks (screw jacks) are mechanical devices used to apply and adjust pressure in shoring systems and are an acceptable alternative to timber when used correctly.

• Screw jacks are commonly used with hydraulic or aluminum shores and timber wales to provide adjustable support and accommodate uneven trench walls.
• They allow fine adjustment of the shoring system and can be useful for shallow to moderate depths where controlled pressure is needed.
• A competent person must ensure they are installed per the manufacturer’s guidance and are capable of resisting expected loads.

See Appendix E to Subpart P (Alternatives to Timber Shoring) for information on trench jacks and other alternatives.

Yes — workers and employers must follow the manufacturer’s instructions and ratings when using alternative shoring systems.

• Manufacturer guidance provides system capacities, maximum allowable spans or depths, proper assembly, and maintenance practices.
• Using components outside of manufacturer specifications can reduce protection and increase collapse risk, so a competent person must verify correct use.
• If manufacturer instructions are unavailable, a qualified person (or engineer) should determine safe limits before use.

Refer to Appendix E to Subpart P (Alternatives to Timber Shoring) and follow the system manufacturer’s directions.

A competent person must evaluate site conditions and select the appropriate protective system or alternative shoring for the trench.

• The competent person inspects the site, classifies the soil, assesses water and surcharge hazards, and determines if an alternative (hydraulic, pneumatic, shields, jacks) is suitable.
• For complex designs or where manufacturer guidance is insufficient, a registered professional engineer may be required to design or approve the system.

See Appendix E to Subpart P (Alternatives to Timber Shoring) regarding selection and use of alternative systems.

Alternative shoring and trench shields must be inspected by a competent person before each shift and after any event that could increase hazard (rain, vibrations, or nearby operations).

• Inspections should check for damage, deformation, hydraulic leaks, loose fittings, misalignment, or signs the system is not holding pressure.
• Damaged or defective components must be removed from service and repaired or replaced per manufacturer instructions before use.

For inspection requirements and safe use of alternatives, consult Appendix E to Subpart P (Alternatives to Timber Shoring).

Alternative shoring components may be used in combination or stacked only if the manufacturer permits it or a qualified person (or engineer) determines the configuration is safe.

• Stacking affects load paths and system capacity; unauthorized stacking can exceed design limits and create collapse hazards.
• Always follow manufacturer guidance or obtain an engineered design before combining components to achieve deeper support.

See Appendix E to Subpart P (Alternatives to Timber Shoring) for guidance on using alternative systems safely.

Alternative shoring systems can be used in a range of soil types, but their selection must match the soil classification and conditions as determined by a competent person.

• Some systems may be suitable for stable rock and Type A/B soils but require different sizing or support in Type C or unstable soils.
• Water infiltration, vibration, and surcharge loads change how a system performs, so the competent person must account for these when selecting and installing the system.

Review Appendix E to Subpart P (Alternatives to Timber Shoring) and have a competent person assess soil and system compatibility.

If a hydraulic shore loses pressure while workers are in the trench, workers should be evacuated immediately and the trench secured until the system is repaired or replaced.

• Loss of pressure can significantly reduce the shore’s support capacity and increase collapse risk.
• A competent person must evaluate the cause (leak, damage, settling), repair or replace components per manufacturer instructions, and re-inspect the trench before re-entering.

See Appendix E to Subpart P (Alternatives to Timber Shoring) for safe use and maintenance of hydraulic systems.

No — alternative shoring systems should not be modified on site in ways that reduce their rated capacity unless a qualified person or the manufacturer approves and documents the modification.

• Field modifications can change load paths, weaken components, and void manufacturer ratings, creating a collapse hazard.
• If an off-the-shelf system does not fit, consult the manufacturer or a registered professional engineer for an approved solution.

Refer to Appendix E to Subpart P (Alternatives to Timber Shoring) and the manufacturer’s instructions before making any changes.

No — trench shields do not eliminate the requirement for safe means of egress; workers must still have access and escape routes appropriate for trench depth.

• OSHA requires a safe means of exit for trenches 4 feet deep or greater; shields provide protection but do not replace ladders, ramps, or other required egress methods.
• Egress points should be located so workers can reach them quickly and without traversing hazardous areas.

See Appendix E to Subpart P (Alternatives to Timber Shoring) and ensure means of egress comply with Subpart P requirements.

The employer is responsible for ensuring workers are trained to recognize excavation hazards and to work safely with alternative shoring systems.

• Training should cover system function, proper entry/exit, recognizing signs of failure, emergency procedures, and when to stop work and notify the competent person.
• The competent person should ensure training content is site-specific and that workers understand the manufacturer’s safe-use instructions.

Consult Appendix E to Subpart P (Alternatives to Timber Shoring) for guidance on proper selection and use of alternatives.

Aluminum hydraulic shores may be used in nonvertical excavations if the system is suitable for the geometry and loads, and a competent person approves their use.

• Nonvertical walls, slopes, or stepped excavations change loading conditions; the system must be capable of resisting the specific soil pressures encountered.
• Use per manufacturer specifications or a site-specific engineered design when conditions differ from typical vertical trench applications.

See Appendix E to Subpart P (Alternatives to Timber Shoring) and involve a competent person for nonstandard excavations.

Damaged alternative shoring components must be removed from service immediately and repaired or replaced in accordance with the manufacturer’s instructions before reuse.

• Damage can include dents, bent members, hydraulic leaks, stripped threads, or any condition that reduces load-carrying capability.
• The competent person must inspect components and tag or segregate any that are unfit for service.

For inspection and maintenance expectations, see Appendix E to Subpart P (Alternatives to Timber Shoring).

A registered professional engineer should be involved when manufacturer guidance is unavailable, when the excavation or loading conditions are complex, or when a site-specific engineered design is needed for safety.

• Situations requiring engineering include unusually deep trenches, nearby structures or utilities creating surcharge loads, unusual soil conditions, or nonstandard system configurations.
• The competent person should request engineering input whenever they cannot confirm a system’s adequacy from available instructions and calculations.

See Appendix E to Subpart P (Alternatives to Timber Shoring) for when engineered designs may be necessary.