Code of safety for excavation work

IS 3764: Scope Summary & Key Tables

Scope:
IS 3764 covers design and construction of temporary excavation supports (sheet piling, wales, struts) in trenches under various soil and hydrostatic pressure conditions.

Key Tables for Excavation Support (Clause 5.4.1)

Table 4: Soil Under Hydrostatic Pressure

Table 3: Loose Sandy or Soft Soil

| Depth of Trench (m) | Sheathing Section (cm) | Max Horizontal Spacing (

IS 3764 - Definitions & Key Specifications Summary

Clause 3.0: Definitions

• Defines terms related to shoring, sheathing, wales, and struts used in trench excavation.
• Refer to Fig. 1 in the standard for graphical representation.

Key Tables for Excavation Support (Clause 5.4.1 & 6.5)

Important Notes:

• Sheathing: Boards or plates placed against the trench walls.
• Wales: Horizontal supports that hold sheathing in place.
• Struts: Vertical or diagonal braces supporting wales.

Visual Concept (Mermaid.js)

graph LR
A[Trench Wall] -- Sheathing --> B[Boards/Plates]
B -- Supported by --> C[Wales (Horizontal)]
C -- Braced by --> D[Struts (Vertical/Diagonal)]

References (Clause 2.1)

• IS 2314: Steel sheet piling
• IS 3696 (Part 2): Scaffolds and ladders safety
• IS 4081: Safety for blasting and drilling

This summary aids in selecting appropriate shoring dimensions

IS 3764 - General Recommendations for Sheet Piling

Key Points from Clause 4 & Related Tables:

• Sheet Piling: A line of piles driven to form a retaining wall or barrier.
• Refer to adjunct standards for steel sections, safety, and blasting:
  • IS 2314: Steel Sheet Piling Sections
  • IS 3696 (Part 2): Safety code for ladders
  • IS 4081: Safety code for blasting

Design Specifications for Support Members (Tables 3 & 4):

• Widths of trench influence strut spacing and size:
  • Less than 2 m: smaller sections and closer spacing.
  • Between 2 m and 4 m: larger sections and spacing.

General Recommendations:

• Use appropriate steel sheet piling sections per IS 2314.
• Spacing of wales and struts depends on soil type, trench depth, and width.
• Ensure safety per IS 3696 and IS 4081 during excavation and blasting.
• Follow max spacing limits for structural stability (horizontal max 3 m for struts).

Visual Concept (Mermaid Diagram):

graph LR
A[Sheet Piling] --> B[Sheathing]
A --> C[Wales]
A --> D[Struts]

Responsibilities of Foremen and Supervisors (IS 3764 - Clause 4.1)

• Appointment: An experienced, competent foreman/supervisor must be in charge, with clear authority and responsibilities.
• Safety Enforcement: They must ensure strict compliance with safety rules, forbid use of defective tools, rigging, or materials.
• Qualification Control: No worker shall perform tasks they are unqualified for.
• Briefing: Workers must be briefed on work plans, hazards, and safety measures before starting.

Inspection Duties (Clause 4.1.1):

• Regularly inspect excavation sides during work.
• Inspect after every rain, storm, or hazard-increasing event.
• Increase protection against slides/cavings as needed.

Additional Safety Notes:

• No internal combustion engines in trenches without proper exhaust control (Clause 15.5).
• Follow IS 4081:1986 for drilling/blasting safety.
• Provide protective measures against insects, vermins, poisonous plants (Clauses 17 & 18).

Summary Table: Foreman/Supervisor Safety Responsibilities

flowchart TD
    A[Foreman/Supervisor] --> B[Enforce Safety Rules]
    A --> C[Inspect Tools & Materials]
    A --> D[Verify Worker Qualifications]
    A --> E[Brief Workers on Hazards]
    A --> F[Inspect Excavation Sides]
    F --> G[After Rain/Storm]
    F --> H[Increase Protection if Needed]

This ensures safe excavation and worksite management per IS 3764.

IS 3764 - Shoring and Timbering Key Specifications

1. Sizes & Spacing (Clause 5.4.1)

• Sheathing, wales, and struts sizes & spacing depend on soil type and trench depth.
• Longer side of rectangular wales/struts kept vertical.

2. Erection (Clause 5.3)

• Follow provisions 5.3.1 to 5.3.4 for erecting shoring members (see Fig.1 in code).

3. Tables for Timbering Members (Clause 5.4.1)

Table 3: Loose Sandy/Soft Soil or Previously Excavated Soil

IS 3764: Loose Side Material - Key Specifications & Tables

Loose side material refers to soil types requiring specific sheathing, wales, and struts in trench shoring.

Key Tables Summary (Clause 6.5 & 5.4.1)

IS 3764: Excavated Material Placement - Key Specifications

1. Shoring & Timbering Sizes and Spacing (Clause 5.4.1)

IS 3764: Tools and Equipment Handling - Key Points

1. Tools and Material Placement (Clause 8.1)

• Keep tools/materials (wheelbarrows, shovels, picks, tiles, cement, lumber) well away from trench edges.
• Prevent accidental falling into trenches.

2. Tools for Workers (Clause 9.4)

• Provide proper tools with ample length for break-down work.
• Warn workers about risks from sudden material movement or falling objects.
• Maintain adequate spacing between workers to avoid accidental strikes by tools.

3. Related Standards for Access and Safety (Clause 2.1)

4. Shoring Timber Sizes (Clause 5.4.1)

• Use Tables 1-4 for sizes and spacing of sheathing, wales, and struts based on soil type.
• Rectangular sections: longer side vertical for strength.

Summary Diagram: Safe Tool Handling Near Trenches

flowchart LR
    A[Tools & Materials] --> B{Placement}
    B -->|Far from edge| C[Safe]
    B -->|Near edge| D[Risk: Fall into trench]

    E[Workers] --> F{Tools}
    F -->|Proper & ample length| G[Safe Operation]
    F -->|Improper| H[Accidents risk]

    E --> I{Spacing}
    I -->|Adequate| J[No accidental hits]
    I -->|Crowded| K[Injury risk]

Note: For detailed timber sizes and spacing, refer to IS 3764 Tables 1-4 based on soil conditions.

IS 3764: Use of Heavy Machinery and Vehicles - Key Points

1. Safe Operation of Internal Combustion Engines (Clause 15.5)

• Exhaust gases must not accumulate in trenches.
• Provide exhaust discharge remote enough to prevent gas return.
• Ensure adequate ventilation or fume neutralization.

2. Machinery Distance from Excavation (Clause 9.1)

• Heavy machinery must be kept at least the trench depth away from excavation edges.
• For trenches deeper than 6 m, maintain a minimum distance of 6 m.

3. Vehicle Control Near Trenches (Clause 9.3)

• Operation under experienced supervision.
• Vehicles must not approach or back into excavation edges.
• Roads to/from trenches must be carefully located.
• Constant vigilance for falling materials during loading.

Summary Table: Minimum Safe Distances for Heavy Equipment Near Excavations

flowchart LR
    A[Heavy Machinery] --> B{Distance from Trench Edge}
    B --> |≤ Trench Depth| C[Safe Operation]
    B --> |≥ 6 m if Depth > 6 m| C
    C --> D[Supervised Vehicle Operation]
    D --> E[No vehicle near edge]
    E --> F[Watch for falling debris]

Note: Follow IS 4081:1986 for blasting safety and maintain all personal protective measures as per IS 3764 for site hazards.

IS 3764: Means of Access and Escape - Key Points

Relevant IS References (Clause 2.1)

• IS 2314:1986 – Steel sheet piling section
• IS 3696 (Part 2):1991 – Scaffolds and ladders - Code of safety: Part 2 Ladders
• IS 4081:1986 – Safety code for blasting and related drilling operation

Access & Escape Specifications (Clause 10)

• Safe and adequate means of access and escape must be provided for workers.
• Ladders and scaffolds should comply with IS 3696 (Part 2).
• Electrical installations near inflammable substances must be explosion-proof (Clause 12.1.3).
• Portable lamps/flashlights used in hazardous areas must be explosion-proof.

Sheathing & Bracing for Trenches Under Hydrostatic Pressure (Table 4, Clause 5.4.1)

IS 3764: Provision of Fences, Guards, and Barricades — Key Specifications

1. General Requirements (Clause 6.5)

• Fences, guards, and barricades must be provided around trenches or excavations to ensure safety.
• Dimensions and spacing depend on soil type, trench depth, and width.

2. Key Tables for Shoring Members (Clause 5.4.1 & 6.5)

3. Specifications Summary

• Sheathing: Timber planks sized per soil and trench depth (e.g., 5x15 cm to 10x20 cm).
• Wales: Horizontal supports spaced vertically as per table (typically 1 to 1.5 m).
• Struts: Vertical or horizontal braces spaced up to 3 m horizontally and 1 to 1.5 m vertically.
• For trenches >6.5 m depth, heavier sections and closer spacing are required.

4. Additional References

• IS 2314: Steel sheet piling sections.
• IS 3696 (Part 2): Safety code for scaffolds and ladders.
• IS

IS 3764 - Provision of Lighting and Warning Signals (Clauses 12.1, 12.1.1, 12.1.2)

Key Specifications:

• Lighting:

  • All public sidewalks/walkways near excavations must be adequately illuminated during darkness.
  • Excavation areas for night work shall be adequately lighted to ensure visibility and safety.

• Warning Signals:

  • At all approaches and exits of excavation sites, danger and warning signals must be placed.
  • In busy/risky locations, a flagman with a red flag should be posted to warn and guide pedestrians and vehicles.
  • Along trenches frequented by the public, suitable warning signals or red lights must be installed and maintained to prevent falls.

Ladder Provision (related safety):

• 1 ladder per 15 m for hazardous work; 1 ladder per 30 m for less hazardous work.
• Ladders must extend at least 1 m above the cut for safe handhold.

Summary Table for Lighting & Warning Signals:

Visual Concept (Mermaid.js):

graph LR
A[Excavation Site] --> B[Approach & Exit]
B --> C[Warning Signals]
B --> D[Flagman with Red Flag]
A --> E[Public Sidewalks]
E --> F[Adequate Illumination]
A --> G[Trench]
G --> H[Red Warning Lights]

Ensure compliance with IS 3764 clauses 12.1, 12.1.1, 12.1.2 for safety during excavation works.

IS 3764 Key Points on Safety Ropes and Lifelines

• Lifelines (Clause 13.2):

  • Must be secured to at least two substantial anchorages or structural members.
  • Manila lifelines for supporting personnel on safety belts must be:
    • Minimum 20 mm diameter.
    • Have a wire core for strength.

• Safety Rope Usage (Clause 13.1):

  • When entering hazardous trenches or scaling rock slopes, a safety rope must be securely tied to the safety belt worn by the worker.
  • This allows the worker to be assisted or pulled to safety if needed.

• Additional Safety:

  • Lone workers are not permitted in trenches unless another worker is nearby (Clause 14).

Summary Table: Lifeline Specifications

Diagram: Lifeline Setup

graph LR
A[Worker with Safety Belt] -- Safety Rope --> B[Lifeline]
B -- Secured to --> C[Anchor 1]
B -- Secured to --> D[Anchor 2]

This ensures safety rope integrity and worker protection during hazardous trench work.

IS 3764 - Key Points for Lone Workers (Clause 14):

• Lone workers are prohibited in trenches unless there is at least one other worker on the ground nearby on duty.
• This ensures immediate assistance in case of emergencies such as collapse, harmful gases, or accidents.

Related Safety Specifications from IS 3764:

Summary Diagram: Lone Worker Safety in Trenches

flowchart TD
    A[Lone Worker in Trench?] -->|Yes| B[Is Another Worker Nearby?]
    B -->|No| C[Prohibited - No Lone Work]
    B -->|Yes| D[Work Permitted with Safety Measures]
    D --> E[Use Lifelines & Safety Devices]
    D --> F[Ensure Proper Ventilation & Gas Monitoring]
    D --> G[Emergency Rescue Plan Ready]

In brief: IS 3764 mandates no lone worker in trenches without backup personnel nearby, emphasizing safety through supervision, lifelines, and protective measures.

IS 3764: Harmful Gases and Fumes – Key Specifications

Safe Air Composition Limits (Clause 15.2.1)

Key Requirements:

• Ventilation: Mechanical ventilation must be provided if harmful gases are detected or likely.
• Testing: Frequent gas tests are mandatory to ensure safe limits.
• Safety: No lone workers allowed in trenches with potential gas hazards (Clause 14).
• Lifelines: Must be secured to at least two substantial anchors; manila lifelines ≥ 20 mm diameter with wire core (Clause 13.2).

Recommended Action Flow for Gas Safety in Trenches:

flowchart TD
    A[Start Work in Trench] --> B[Check for Harmful Gases]
    B -->|No gases detected| C[Proceed with Work]
    B -->|Gases detected| D[Measure Gas Concentration]
    D --> E{Gas within Safe Limits?}
    E -->|Yes| C
    E -->|No| F[Provide Mechanical Ventilation]
    F --> G[Retest Gas Levels]
    G --> E
    F --> H[Do Not Allow Lone Workers]
    H --> I[Ensure Lifelines Secured]

Summary:
Ensure air quality meets the specified limits before and during trench work. Provide mechanical ventilation and continuous monitoring where harmful gases exist. Follow safety protocols for lifelines and personnel presence.

IS 3764: Drilling and Blasting Operations - Key Points

Safety & Operational Guidelines (Clauses 5.6.2, 15.5, 16)

• Post-blasting inspection: After blasting, a competent person must check steep excavation side slopes for loose rocks; remove all loose rocks before work resumes.
• Personal Protective Equipment: Helmets are mandatory for workers in blasted excavations.
• Engine operation in trenches: Internal combustion engines must have exhaust systems ensuring fumes do not accumulate inside trenches.
• Safety standard reference: Follow IS 4081:1986 for detailed safety codes on blasting and drilling.

Key Specifications:

• Slope stability: Examine and remove loose rock after each blast.
• Ventilation: Ensure exhaust gases from engines are safely discharged away from trenches.
• Protective measures: Use helmets and follow IS 4081 for blasting safety.

Recommended Reference Table for Shoring (Clause 5.4.1)

Summary Diagram of Drilling & Blasting Safety Workflow

flowchart TD
    A[Drilling & Blasting] --> B[Blast Operation]
    B --> C[Inspection of Side Slopes]
    C -->|Loose Rock Found| D[Remove Loose Rock]
    C -->|No Loose Rock| E[Resume Work]
    D --> E
    E --> F[Ensure PPE - Helmets]
    F --> G[Safe Engine Operation in Trenches]
    G --> H[Follow IS 4081 Safety Code]

For detailed formulas, charge calculations, and blast design, refer to IS 4081:1986, which provides comprehensive guidelines on drilling patterns, charge sizes, and safety distances.

IS 3764 - Protection Against Insects, Leeches, Vermins, and Snakes (Clause 17)

Key safety measures include:

• Personal Protection: Use boots, hoods, netting, gloves, masks.
• Hazard Awareness: Provide instructions on potential risks.
• Environmental Controls:
  • Drainage or spraying of breeding areas.
  • Burning or destruction of nests.
  • Use of smudge pots for small area protection.
  • Eliminate unsanitary conditions that propagate vermin.
• Rodent Control: Implement extermination measures.
• Health Measures: Provide inoculation and approved first-aid remedies.

Summary Table of Controls

Note: These measures are preventive and should be combined for effective protection on-site.

Additional Tips:

• Ensure regular training on hazard identification.
• Maintain clean work environments to reduce vermin habitats.
• Use approved chemical sprays and follow manufacturer guidelines.

flowchart TD
    A[Hazard Awareness] --> B[Personal Protection]
    A --> C[Environmental Control]
    C --> D[Drainage & Spraying]
    C --> E[Nest Destruction]
    C --> F[Sanitation]
    A --> G[Rodent Control]
    A --> H[Health Measures]
    H --> I[Inoculation]
    H --> J[First Aid]

This approach aligns with IS 3764 Clause 17 for safe excavation and construction work in infested areas.

IS 3764 – Protection Against Poisonous Plants (Clause 18)

Key protective measures when exposed to poisonous plants like poison ivy, oak, surmac:

• Identification & Training: Workers must be trained to identify poisonous plants and understand preventive steps.
• Removal: Where feasible, poisonous plants should be destroyed or removed.
• Protective Clothing: Use gloves, long sleeves, and other protective garments.
• Protective Ointments: Provide barrier creams or ointments to reduce skin absorption.
• Hygiene: Availability of soap and water for washing exposed skin immediately after contact.
• First-Aid: Approved remedies for treating affected skin areas must be accessible.
• Immunisation: Provide immunisation treatments if applicable.

Summary Table of Protective Measures

flowchart TD
    A[Exposure to Poisonous Plants] --> B[Training & Identification]
    A --> C[Plant Removal]
    A --> D[Protective Clothing & Ointments]
    A --> E[Washing Facilities]
    A --> F[First-Aid Remedies]
    A --> G[Immunisation]

This ensures worker safety against toxic plant hazards per IS 3764 Clause 18.

IS 3764 Key Points on Overhangs and Slopes

Overhangs (Clause 19.1)

• Overhangs: projections of frozen/cemented gravel, sand, boulders, or consolidated clay from trench walls.
• These are unstable and can fall unexpectedly.
• Must be removed before further excavation to ensure safety.

Slopes & Shoring (Clause 6.5 & Tables 2, 3, 4)

• Slopes depend on soil type and trench depth.
• Sheathing, wales, and struts sizes and spacings vary with trench depth & soil condition.
• Tables provide detailed specs for:

• Width of member depends on trench width and soil stability.
• Max horizontal spacing for sheathing decreases with loose soil.
• Vertical spacing of wales and struts generally 1–1.5 m.
• Horizontal spacing of struts max 3 m.

Summary Diagram: Excavation Support Elements

graph TD
    A[Trench Wall] --> B[

IS 3764: Undercutting - Key Specifications & Tables

Undercutting refers to excavation below the foundation or trench bottom, requiring proper shoring/timbering to prevent collapse.

Clause 5.4.1 & 6.5: Sheathing, Wales, and Struts for Undercutting

• Selection depends on soil type and depth of trench.
• Tables 1 to 4 specify section sizes and spacing for sheathing, wales, and struts.
• Longer side of rectangular wales/struts is vertical.

Summary of Tables for Different Soil Types (Depth 6.5m to 10m):

Important Notes:

• Width of Member: Sheathing horizontal spacing is limited by the member width.
• Spacing: Vertical and horizontal spacing of wales and struts depend on trench width and soil type.
• For trenches over 6.5 m but not over 8 m, and over 8 m but not over 10 m, use corresponding table rows.

Quick Formula for Strut Spacing (Example):

For trench width ( W \leq 2m ):

[

IS 3764: Shelters for Workers - Key Points & Specifications

While IS 3764 focuses on safety in trenches and excavations, Clause 15.5 and related sections emphasize worker safety, including shelter and environmental hazards. Key points relevant to shelters for workers:

1. Exhaust & Fume Safety (Clause 15.5)

• No internal combustion engines inside trenches unless exhaust gases are safely vented away.
• Prevent accumulation of harmful gases in worker areas.

2. Environmental Protection (Clauses 17 & 18)

• Protection against insects, vermin, snakes, and poisonous plants.
• Provide personal protective equipment (boots, gloves, masks).
• Adequate drainage, spraying, and sanitation to reduce hazards.
• First-aid and immunization must be available.

3. Shoring & Timbering for Shelters (Clause 5.4.1 & Table 4)

• Use appropriate sizes and spacing of sheathing, wales, and struts based on soil type and trench depth.
• For soil under hydrostatic pressure, Table 4 specifies:

IS 3764: Temporary Supports for Foundations — Key Specifications

1. Timber Sizes & Spacing for Shoring (Clause 5.4.1)

2. Important Notes:

• Wales and struts: When rectangular, longer side vertical.
• Spacing: Horizontal spacing for sheathing and wales varies with soil type and trench depth.
• Struts spacing: Vertical and horizontal spacing depend on trench width (≤2 m or 2–4 m).

3. Example Extract from Table 4 (Hydrostatic Pressure, Depth 3 to 5 m)

|

IS 3764: Walkways and Bridges — Key Specifications & Tables

1. Sheathing, Wales & Struts for Excavations (Clause 5.4.1 & 6.5)

Design depends on soil type and trench depth. Key parameters:

2. Width of Member for Loose Side Material (Clause 6.5)

• For trench depths 6.5 to 8 m and 8 to 10 m, width of members is specified as per soil type and load.
• Typical width ranges from 5 cm to 10 cm

IS 3764: Dangerous Areas - Key Specifications & Tables

1. Dangerous Gas Accumulation (Clause 15.4 & 15.5)

• Flammable gas limit: Air containing >1.5% by volume flammable gas is dangerous.
• Internal combustion engines: Must ensure exhaust gases are harmless or discharged away from trench to prevent accumulation.

2. Safety in Drilling & Blasting (Clause 16)

• Follow IS 4081:1986 for blasting safety precautions.

3. Protection Against Biological Hazards (Clauses 17 & 18)

• Use personal protective equipment (boots, gloves, masks).
• Drain or spray breeding areas.
• Remove poisonous plants or use protective clothing and ointments.
• Provide first aid and immunization as needed.

4. Sheet Piling & Bracing for Trenches Under Hydrostatic Pressure (Table 4, Clause 5.4.1)

Common Hazards in Excavation (IS 3764 Highlights)

1. Shoring & Timbering (Clause 5.4.1)

• Use Tables 1-4 for sizes & spacing of sheathing, wales, struts based on soil type:
  • Table 1: Hard soil
  • Table 2: Soil that may crack/crumble
  • Table 3: Loose, sandy, soft soil or previously excavated soil
  • Table 4: Soil under hydrostatic pressure
• Rectangular wales/struts: longer side vertical

2. Hazardous Gases (Clause 15.5)

• No internal combustion engines inside trenches unless exhaust fumes are safely discharged away to avoid accumulation.

3. Drilling & Blasting (Clause 16)

• Follow safety precautions as per IS 4081:1986.

4. Biological Hazards (Clauses 17 & 18)

• Protection from insects, vermins, snakes, poisonous plants via:
  • Instruction, protective gear (boots, gloves, masks)
  • Drainage, spraying, nest destruction
  • First-aid and immunization
  • Removal of poisonous plants and protective ointments

5. Overhangs & Slopes (Clause 6.1)

• Remove or brace loose stones, unstable pockets.
• Avoid workers working vertically above one another on steep slopes.

Example: Shoring Spacing (from typical IS tables)

(Refer IS 3764 Tables 1-4 for exact values)

flowchart TD
    A[Excavation Hazards] --> B[