3.3 Mobile Elevating Work Platforms (MEWPs), Ladders, Tower Scaffolds & Fragile Roof Safety

Temporary access equipment—including Mobile Elevating Work Platforms (MEWPs), prefabricated tower scaffolds, ladders, and roof access gear—enables work at height across diverse construction tasks. Selecting the correct equipment type and enforcing strict operating rules is a primary duty for SMSTS-qualified Site Managers.

Mobile Elevating Work Platforms (MEWPs)

MEWPs provide mechanical access for high-level tasks. In the UK, MEWP operator competence is recognized through the International Powered Access Federation (IPAF) Powered Access License (PAL Card).

Primary MEWP Categories (BS ISO 18878):

• Category 1A (Static Vertical): Vertical personnel lifts with outriggers that cannot move under load.
• Category 1B (Static Boom): Trailer-mounted or vehicle-mounted boom lifts with outriggers.
• Category 3A (Mobile Vertical): Scissor lifts capable of driving while elevated.
• Category 3B (Mobile Boom): Self-propelled boom lifts (cherry pickers) capable of driving while elevated.

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MEWP Safety Rules and Harness Restraint Policy

Site Managers must enforce strict operational controls on MEWPs:

1. Boom-Type MEWPs (Category 1B & 3B Harness Policy):
   Occupants inside a boom-type MEWP platform must wear a full-body harness attached via an adjustable work restraint lanyard to a designated internal anchorage point. This prevents the 'catapult effect'—where sudden boom movement or ground drop ejections throw the occupant out of the basket.

2. Scissor Lifts (Category 3A Harness Policy):
   In vertical scissor lifts, guardrail enclosure provides primary fall prevention. Work restraint harnesses are generally not mandatory unless a specific risk assessment identifies an ejection hazard (e.g., operating on uneven terrain or near live traffic).

3. Ground Bearing Capacity and Outriggers:
   Outriggers and stabilizers must be fully deployed onto heavy-duty spreader pads to distribute point loads over soft ground, unmade soils, or underground voids.

4. Emergency Lowering Protocols:
   Prior to starting work, operators and nominated ground personnel must verify that the ground-level emergency descent controls and manual hand pumps are fully operational.

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Prefabricated Mobile Tower Scaffolds (PASMA & BS EN 1004)

Prefabricated aluminum tower scaffolds must be erected, altered, and dismantled under the supervision of a competent person holding a Prefabricated Access Suppliers' and Manufacturers' Association (PASMA) qualification.

Mandatory Tower Assembly Methods:

To protect operatives from fall hazards during erection, towers must be assembled using one of two approved methods:

• Through The Trap (3T) Method: Operatives position themselves seated inside the open trapdoor of the working platform to install upper guardrail frames before stepping fully onto the deck.
• Advance Guardrail (AGR) System: Temporary or permanent guardrail frames are locked into place from the deck level below before the higher platform is accessed.

+-------------------------------------------------------------------------+
| Tower Assembly Height Limits (BS EN 1004 Standard):                    |
| - Maximum Internal Height (Indoors, no wind): 12.0 meters               |
| - Maximum External Height (Outdoors, wind loads): 8.0 meters            |
| - Maximum Height-to-Base Ratio: 4:1 (Internal) / 3.5:1 (External)       |
+-------------------------------------------------------------------------+

Critical Tower Safety Rules:

• Movement Controls: Never move a mobile tower while personnel, materials, or loose tools are on board. Towers must only be pushed manually at or near the base. Maximum tower height during movement must not exceed 4.0 meters.
• Wheel Castors: All castor wheels must be securely locked before anyone ascends the tower.
• Outriggers & Stabilizers: Outriggers must be attached as specified by the manufacturer's instruction manual as platform height increases.

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Portable Ladders and Stepladders (WAHR 2005 & INDG402)

Under WAHR 2005, ladders are not prohibited, but their legal use is restricted. Ladders must only be used as working platforms for low-risk, short-duration tasks (up to 30 minutes maximum duration, carrying light loads under 10 kg) where higher-level equipment is unfeasible due to site constraints.

Leaning Ladder Set-Up Standards:

• Pitch Angle (1:4 Rule): Leaning ladders must be set at an angle of 75 degrees—representing a ratio of 1 unit out at the base for every 4 units of vertical height.
• Securing: Ladders must be secured against slipping by tying stiles at the top, employing a stability device at the foot, or footed by a co-worker as a last resort.
• Overhang at Landing Points: Ladders used for access to another level must extend at least 1.0 meter (or 3 rungs) above the stepping-off platform surface.
• Three Points of Contact: Operatives must maintain 3 points of contact (two feet and one hand, or two hands and one foot) at all times during ascent and descent.
• Electrical Hazards: Non-conductive fiberglass or wooden ladders must be used when working near live electrical services.

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Fragile Roof Safety (HSG33 Guidance)

Falls through fragile roof surfaces account for a significant proportion of height fatalities. Guidance publication HSG33 (Health and Safety in Roofwork) sets out the mandatory approach to fragile roof management.

Common Fragile Roof Materials:

• Asbestos cement sheets and fiber cement sheeting.
• Corroded metal roof sheets.
• Polycarbonate skylights, roof lights, and plastic dome lights.
• Wood wool slabs and slate roofs.
• Glass panes.

The Golden Rule of Roof Safety:

Site Managers must always assume a roof surface is fragile until a thorough structural assessment by a competent person proves otherwise.

+-------------------------------------------------------------------------+
| Fragile Roof Hierarchical Controls (HSG33):                             |
| 1. Work from beneath using MEWPs or tower scaffolds.                     |
| 2. Install perimeter guardrails and under-deck safety nets.             |
| 3. Use staging boards or crawling ladders spanning purlins.             |
| 4. Post prominent warning notices: 'DANGER: FRAGILE ROOF'.              |
+-------------------------------------------------------------------------+

Mandatory Controls for Fragile Roof Work:

• Operatives must never step directly onto fragile roof sheets or skylights.
• Use staging boards, crawling ladders, or walkway systems fitted with guardrails to distribute body weight over structural roof purlins.
• Install safety nets or soft landing airbags directly beneath fragile roof decks to arrest falls if a worker slips.
• Erect physical boundaries and cover skylights with timber covers rated to withstand impact.
• Fix clear, permanent warning notices at every ladder access point reading: "DANGER: FRAGILE ROOF—USE STAGING BOARDS".