MASCI Trench Safety · Tabulated Data
Tabulated Data Library
Manufacturer-engineered, OSHA-compliant data for every MASCI trench box. Per-box PDFs, soil-type limits, spreader configurations, and shield depth ratings.
Match the box to the right sheet. Tabulated data is specific to the manufacturer, model, soil type, and configuration. If you can't find the sheet that matches the box on site, stop and contact Safety.
Looking for OSHA general guidance, competent-person reminders, or what to do if pins/labels are missing? Open Safety References
Read Before You Enter The Box
What is Tabulated Data?
And why it matters in the field
Every trench shield on a MASCI job has an engineer-approved data sheet that tells you exactly how deep you can dig, in what kind of soil, with what spreaders, and under what conditions. Read it before you enter the box. Every time.
OSHA's Definition
- Tabulated Data means tables and charts approved by a registered professional engineer and used to design and construct a protective system.
- The document must be in written form on the jobsite during construction of the protective system.
- 'Construct' means to place, position, or reposition — NOT just assemble.
Protective System Options
- OSHA Charts — Sloping and Benching, Timber Shoring, Aluminum Hydraulic Shoring.
- Designs by a Registered P.E. — Manufactured Trench Shields, Site-Specific Designs.
- All options were produced by professional engineers. All data is presented as tables (rows and columns) — learn to read them.
OSHA Subpart P — The Rule
- Shield (Shield system) means a structure that is able to withstand the forces imposed on it by a cave-in and thereby protect employees within the structure.
- Protective systems will have the capacity to resist — without failure — all loads that are intended or could be reasonably expected to be applied or transmitted to the system.
- Shield systems shall NOT be subjected to loads exceeding those which the system was designed to withstand.
What's in a Tabulated Data Sheet
- Identity and contact info of the manufacturer.
- Soil classification (OSHA Type A / B / C with lateral-earth-pressure values 25 / 35 / 45 / 60 / 80 psf).
- Maximum working depths for each soil type.
- Capacity of the shield and allowable loads.
- Assembly and inspection instructions.
- Safety recommendations and limits.
- Spreader size, length, and placement requirements.
- A P.E.'s stamp and signature — if it's missing, the data is not valid.
The Competent Person — Who Is That?
- Someone knowledgeable and capable of complying with all federal regulations, state and local laws, and ordinances.
- Trained and experienced in the proper use of trench shields, safe excavation practices, and soil classification methods.
- MUST direct and control the use of every trench shield on the job.
- Classifies the soil IN ACCORDANCE with OSHA guidelines — no guessing.
Managing Soil at the End of a Shield
- Shields are designed for LINEAR trench application.
- The ends of shields were intended to be OPEN, with no vertical wall of soil pressing against them.
- Soils at the end should be no more steep than 1½ : 1 (that's a 1½-foot horizontal run for every 1 foot of depth).
- If you must cap the ends with steel plate, follow the manufacturer's end-load technical data sheet — it has its own depth limits.
Common Practices That CONFLICT With Tabulated Data
- End loading (soil pressing against the open ends).
- Side loading (uneven soil pressure across the panels).
- Inappropriate spreader usage or placement.
- Failure to comply with surcharge limits.
- Active vehicular traffic loads on top of the shield.
- Lack of groundwater extraction (water adds pressure).
- Using manufactured goods that have NO tabulated data at all.
- Incorrect box positioning or movement in the trench.
- ANY deviation from the manufacturer's data requires WRITTEN P.E. approval before work continues.
Surcharge Loads — 72 psf Maximum
- Surcharge = extra load from stuff near the trench (heavy equipment, spoil piles, traffic, vibrations, adjacent buildings).
- 'Adjacent' means within a horizontal distance from the edge of the trench equal to the depth of the trench. A 10-ft deep trench has a 10-ft adjacent zone.
- Tabulated data depth ratings typically account for a MAX 72 psf lateral surcharge. Above that, the shield is NOT rated.
- The competent person MUST verify this limit is not exceeded — if it is, call a P.E. for written direction.
- Surcharge can reduce your allowable working depth dramatically. Don't skip this step.
Radial Load on Spreaders
- Typical steel trench shields use 8-inch Schedule 80 pipe spreaders.
- The spreader's STRENGTH is along its axis (axial load).
- Axial loads COMBINED with radial (sideways) loads were NOT part of the design calculation for working depth.
- The LOWERMOST spreader — the one under compression — is the most susceptible to failure if you add radial load.
- Never hang material on a spreader. Never climb on one. Never use one to lift/move the box.
When Deviation Is Required
- A registered P.E. engineer MUST approve any deviation.
- The approval MUST be in written form BEFORE changes are made.
- The approval document is treated the same as tabulated data — keep it on the jobsite.
- Can be a Technical Data Sheet, an Approval Letter, or a Site-Specific Plan.
- Limits of the deviation must be specific (which box, what depth, what soil type, what conditions).
- If you're not 100% sure what you're doing counts as a deviation — stop, call the office, ask.
Assembly & Disassembly — Every Time
- Inspect shields before AND after assembly. A competent person does the inspection.
- All damage must be evaluated and repairs made under the direction of a registered P.E. Replace missing or damaged parts with OEM parts only.
- Rigging: evaluate rated capacity, inspect for damage, use only the designated lifting points on a shield.
- Tag lines keep crew members away from pinch points and overhead loads.
- All spreaders, pins, and keepers installed PER the manufacturer's tabulated data — exactly the right spec, quantity, and position.
- Lay the box flat on firm, level ground before dismantling. Never dismantle on a slope or dunnage.
- Never enter a box while an excavator is moving it. Never climb spreaders. Never exit a box into an unsupported area.
- Watch for unbalanced loads during lift — a crane and rigging plan may be required for long arch-spreader extensions.
The Bottom Line
- Tabulated data is SPECIFIC to each make and model of trench shield. Different manufacturers = different data.
- Soil type is CRITICAL — classification is non-negotiable and done by a competent person.
- Surcharge loads reduce your allowable depth. Account for them.
- Any deviation = written P.E. approval BEFORE work.
- Proper assembly and handling are just as critical as the design — shields can fail even when correctly rated if installed wrong.
- Read the data sheet BEFORE you get in the box. Every job. Every time.
Field Reference
Tabulated Data Library
Manufacturer tabulated-data PDFs, technical data sheets, and educational resources — one folder per trench box plus a shared General / Educational folder. Total: 6 files across 1 folders.