0. JSA Risk Assessment Preview: Concrete Structure Demolition Operations Using a Hydraulic Breaker

1. On-Site Incident & Hazard Analysis

A. [Hypothetical Sample Case] Excavator Fall and Structural Collapse Due to Loss of Substructure Support

Note: The following is an illustrative, hypothetical incident designed solely for risk assessment training.

During a commercial building demolition project in Greater London, a 360-degree excavator equipped with a hydraulic breaker was hoisted onto the second-floor suspended slab to demolish the concrete decking. To accelerate the project programme, the demolition crew installed only half of the temporary propping specified by the Temporary Works Coordinator (TWC) on the ground floor beneath the active work zone before commencing breaker operations.

As the powerful vertical impacts of the hydraulic breaker transmitted through the slab into the substructure, the inadequate falsework failed to withstand the combined dynamic load of the hammering and the static weight of the excavator, resulting in immediate buckling. Instantly, the slab fractured in a V-shape collapse mechanism, dropping the excavator partially through the floor. The operator sustained severe contusions when the cab violently jolted, and a banksman on the ground miraculously avoided fatal crushing from the falling debris. The Health and Safety Executive (HSE) investigation cited critical failures under the CDM 2015 Regulations. This hypothetical scenario clearly demonstrates the absolute necessity of rigorous structural engineering reviews and the installation of comprehensive temporary works to account for dynamic breaker loads during demolition.

B. Structural, Mechanical, and Regulatory Hazard Mechanisms

Concrete demolition using a hydraulic breaker is an extremely high-risk operation that converts massive hydraulic energy into destructive impact force, maximising mechanical vibration and structural instability. The high-frequency vibrations generated during breaker strikes rapidly propagate micro-cracks within the concrete. If these vibrations transmit to adjacent load-bearing columns or beams, they can induce unintended, catastrophic progressive collapses. Specifically, when operating on suspended slabs, the static weight of the excavator combined with the dynamic recoil (impact load) of the breaker exerts pressures that far exceed the original design limits of the floor.

Furthermore, the mechanical fracturing process expels concrete fragments as high-velocity projectiles capable of inflicting blunt force trauma or penetrating injuries. It also generates dense clouds of Respirable Crystalline Silica (RCS), leading to severe respiratory diseases such as silicosis. Therefore, enforcing strict slewing radius exclusion zones, executing engineered propping plans, installing debris netting, and utilising continuous water suppression are mandatory engineering controls under UK statutory regulations.

🚨 UK Statutory Regulations & Safety Standards (HSE, CDM 2015 & BS 6187)

Construction (Design and Management) Regulations 2015 (CDM 2015): Mandates that a principal contractor must plan, manage, and monitor the construction phase to ensure demolition works are carried out without risks to health and safety, requiring formal structural assessments and temporary works designs by a competent TWC.

Control of Substances Hazardous to Health Regulations 2002 (COSHH): Requires employers to assess and control the risks of exposure to Respirable Crystalline Silica (RCS) dust through engineering controls like water suppression and the provision of FFP3 respiratory protective equipment.

Provision and Use of Work Equipment Regulations 1998 (PUWER): Dictates that heavy plant, such as excavators and quick-hitches, must be suitable for the intended use, maintained in a safe condition, and inspected regularly to prevent mechanical failures and dropped attachments.

BS 6187:2011 (Code of practice for full and partial demolition): Establishes industry best practices for conducting structural surveys, managing vibration limits, and implementing safe systems of work during mechanical demolition.

2. Standard Data Entry Guide for Smart JSA Bridge

To ensure the Smart JSA Bridge platform generates safety control measures fully compliant with UK HSE demolition standards and BS 6187, enter the following standardised job steps into the system:

• [Step 1] Engineering Survey and Exclusion Zone Setup

  • Detailed Description: Conduct CAT & Genny scans for underground services; verify shut-offs; install heavy-duty hoarding; deploy banksmen to prevent unauthorised entry.

• [Step 2] 360-Degree Excavator Mobilisation and Positioning

  • Detailed Description: Level and compact operating ground; use steel plates if necessary; verify backup alarms; strictly barricade and enforce the excavator's slewing radius.

• [Step 3] Concrete Demolition (Hydraulic Breaker/Pecker Operation)

  • Detailed Description: Install shatter-resistant cab glass and debris netting; mandate ear defenders; enforce safe distances to prevent struck-by projectile injuries.

• [Step 4] Vibration Impact and Collapse Monitoring

  • Detailed Description: Install vibration sensors on adjacent structures; erect TWC-approved temporary falsework (propping) under slabs before upper-level demolition.

• [Step 5] Debris Wetting (Dust Suppression) and Tipper Loading

  • Detailed Description: Apply continuous water spray to suppress silica dust; mandate FFP3 masks; prohibit personnel from standing below the excavator bucket during tipper loading.

• [Step 6] Equipment Shutdown, Attachment Check, and Demobilisation

  • Detailed Description: Relieve hydraulic residual pressure; inspect high-pressure hoses for leaks; verify quick-hitch safety pins under PUWER guidelines; park safely.

3. Recommended Final JSA Document (Database Sample)

Below is the final JSA document generated based on automated system recommendations and adapted for UK construction and demolition standards:

4. JSA Engineering Mechanism for Demolition: Collapse Prevention and Silica Control

Concrete structure demolition using a hydraulic breaker demands rigourous engineering controls and strict compliance with HSE regulations to prevent catastrophic structural collapses, fatal struck-by/crushing incidents within the equipment's slewing radius, and long-term silica exposure. Vague instructions such as "watch out for flying rocks" or "be careful not to collapse the floor" are entirely inadequate for HSE compliance audits and fail to prevent site fatalities.

Smart JSA Bridge utilises an automated risk analysis algorithm calibrated against the CDM 2015 Regulations, COSHH, and BS 6187 to deliver real-time, actionable hazard controls.

By inputting 6 structured job steps, the algorithm calculates required technical controls—including mandatory temporary works propping protocols based on dynamic plant loads, precise exclusion zone radii to prevent slewing-radius fatalities, water delivery rates for silica dust suppression, and specific PPE requirements for high-decibel impact noise.

Site Managers, Temporary Works Coordinators (TWC), and Demolition Supervisors can customise these parameters with a single click to match specific plant specifications and structural engineering demolition plans across UK construction projects.

Streamline your safety documentation workflow while ensuring total statutory compliance for high-risk heavy plant demolition operations. Generate your customised risk assessment today.

👉 Enter job steps on Smart JSA Bridge and generate your custom JSA (smartjsabridge.com)