Portable ladders, supported scaffolds, and aerial lifts let you get to a work area and support you while you work. They make getting to a work area easy, but they can cause falls when they're not used properly.
Portable ladders are versatile, economical, and easy to use. However, workers sometimes use them without thinking about using them safely. Each year, most workers are injured when they fall from ladders. Most of the falls are less than 10 feet.
Types of portable ladders. We use ladders to do all sorts of tasks, so it's not surprising that many types of ladders are available. Let's look at the most common types.
Supported and Suspended Access
Common Types of Portable Ladders
Straight Ladder: The most common type of portable ladder. The length cannot exceed 30 feet. It is available in wood, metal and reinforced fiberglass.
It supports only one worker.
Platform Ladder: It has a large stable platform near the top that supports only one worker. The length cannot exceed 20 feet.
Extension Ladder: Extension ladders offer the most length in a general-purpose ladder. They have two or more
adjustable sections. The sliding upper section must be on top of the lower section. Made of wood, metal, or fiberglass. Maximum length depends on material.
Supports only one worker.
Trestle Ladder: These have two sections that are hinged at the top and form equal angles with the base. They are used in pairs to support planks or staging.
The rungs are not used as steps. The length cannot exceed 20 feet.Photo: Courtesy of: us.wernerco.com
Tripod (Orchard) Ladder: These have a flared base and a single back leg that provides support on soft, uneven ground. The length cannot exceed 16 feet. Metal and reinforced fiberglass versions are available.
It supports only one worker. Photo: Courtesy of: us.wernerco.com
Standard Folding Ladder: Has flat steps, a hinged back and is not adjustable. Use only on firm, level surfaces. It is available in metal, wood, or reinforced fiberglass.
It must have a metal spreader or locking arm and cannot exceed 20 feet. It only supports one worker. Photo: Courtesy of: us.wernerco.com
It's important to choose the right ladder for the right job. Using a ladder for a task that it was not designed for may increase the risk of falling.
How Falls from Ladders Occur
Most workers fall from unstable ladders that shift or tilt when the workers climb too high or reach too far beyond the side rails. Workers also fall when they slip on rungs while they're climbing or descending and when vehicles strike the ladders. Workers can reduce their risk of falling by doing the following:
Stand at the base of the ladder with your toes touching the rails. Extend your arms straight out in front of you. If the tips of your finger just touch the rung nearest your shoulder level, the angle of your ladder has a 4:1 ratio.
Inspect ladders frequently and maintain them.
Match work tasks to appropriate ladders.
Set up ladders correctly. Use the 1 to 4 rules. One foot out from wall for every four feet of height.
Climb and descend ladders properly. Both hands should be free.
Always use the three-point rule. "Two feet - One hand" or "Two hands - One foot" making contact at all times.
Keep the following in mind when you use a portable ladder:
Select the most appropriate ladder for the task.
Inspect the ladder before using it; make sure it's in good condition.
Angle straight ladders and extension ladders properly. It should have a 4-to-1 slope (height to base).
Protect the base of a ladder to prevent others from accidentally striking it.
Select a ladder that will extend at least 36 inches above the access area, or provide a grab rail so that workers can steady themselves as they get on or off. Make sure that the ladder is stable. If the ladder could be displaced by work activities, secure it.
Face the ladder when you climb or descend it, keeping at least one hand on the rails.
Stay within the side rails when climbing or working from the ladder. You can reach out, but keep the rest of your body within the rails.
Raise and lower heavy loads with a hand line or a hoist.
Make sure metal ladders have steps and rungs with skid-resistant surfaces.
Allow only one person on the ladder. Use a scaffold if two or more people need to work together.
Never stand on top of a portable ladder.
Never use ladders that have conductive side rails near exposed energized equipment.
Of the many types of supported scaffolds, fabricated frame scaffolds are the most common. Like portable ladders, they're versatile, economical, and easy to use. You'll see them on construction sites as single supported platforms and multiple platforms stacked several stories high on modular frames.
How Falls From Scaffolds Occur
Workers fall from scaffolds when components fail, planks break, handrails give way, and scaffold supports collapse. However, most scaffold accidents can be traced to untrained or improperly trained workers.
When fall-protection systems are required. If you work on a supported scaffold more than
10 feet above a lower level, you must be protected from falling. Guardrails at least 42 plus or minus 3 inches high are appropriate for most scaffold platforms. If you can't use a guardrail system, then you must use a personal fall-arrest system or restraint system. We'll discuss personal fall-arrest systems later in the course.
Those who work from scaffolds must be trained to recognize fall hazards and to control or minimize the hazards. Training must cover the following:
Scaffold load capacity and the types of loads appropriate for the scaffold.
When fall protection is required, the appropriate protection to use, and how to use it.
How to use scaffold components.
How to reach access areas.
How to protect those below the scaffold from falling objects.
How to avoid electrical hazards.
Safe Practices on Scaffolds
Use ladders or stairs to reach platforms that are more than 2 feet above or below the access point.
Don't climb cross-braces to reach a scaffold platform.
Scaffolds must be able to support their own weight and at least four times the maximum intended load. The maximum intended load includes workers, equipment, and supplies.
Platforms must not deflect more than 1/60 of the span when they are loaded.
Platforms must be fully decked or planked between the front uprights and the guardrail supports.
Don't use damaged scaffold components; repair or replace them immediately.
Make sure a competent person inspects the components before each workshift.
Don't modify components.
Scaffold components made by different manufacturers may be mixed, provided they fit together without force and maintain structural integrity.
Watch for slippery surfaces. Don't work on platforms covered with snow and ice.
Stay off scaffolds during storms and strong winds unless a competent person determines that it's safe.
Keep a safe distance from power lines and any other conductive source.
Minimum clearance distances:
Uninsulated electrical lines: 10 feet
Insulated lines more than 300 volts: 10 feet
Insulated lines less than 300 volts: 3 feet
Scaffolds must be erected, dismantled, or moved only under the supervision of a competent person. The competent person must be on site to direct and supervise the work.
Types of Aerial Lifts
Most aerial lifts have extensible or articulating mechanisms that can position workers up, down, or sideways. ANSI defines and sets operating standards for four different types of aerial lifts:
Vehicle-mounted elevating and rotating lifts (ANSI A92.2 devices).
Manually propelled elevating work platforms (ANSI A92.3 devices).
Boom-supported elevating work platforms (ANSI A92.5 devices).
Self-propelled elevating work platforms and scissor lifts (ANSI A92.6 devices).
How Aerial Lift Falls Occur
Click to play video
Most accidents involving aerial lifts can be traced to untrained or improperly trained workers. Reasons for falls:
A hydraulic cylinder fails and causes the boom to drop.
Outriggers are not used or improperly placed and the lift vehicle overturns.
Workers are not tied off while they are in the bucket.
Workers fall or are pulled off the platform when the lift vehicle is struck by another vehicle or moves unexpectedly.
Appropriate Fall Protection
If you work from an aerial lift, you must be protected from falling. The type of fall protection you need depends on the type of lift you use. Most platforms must have a guardrail and each worker may be required to use a personal fall-arrest system: a full-body harness and lanyard attached to the boom or the platform.
Safe Practices On Aerial Lifts
Keep in mind the following when you use an aerial lift:
Use the lift only for its intended purpose and follow the manufacturer's instructions. Keep the operating manual with the lift.
Keep the lift level and stable; use outriggers and intermediate stabilizers.
Never move the lift when the boom is up and workers are on the platform.
Stand on the platform floor. Don't sit or climb on the edge of the basket, guardrail, or midrail.
Be sure to close the access gate while you're working from the platform.
Inspect the lift before using it to make sure that it's working properly and is in good condition.
Know the lift's rated load capacity and don't exceed it.
Stay at least 10 feet away from electrical power lines.
Never use the lift during severe weather.
Use warning signs or barricades to keep others out of the work area.
Never tie off to equipment or to a structure next to the platform.
Portable ladders, supported scaffolds, and aerial lifts provide easy access to most elevated work areas. When they're not feasible or safe, however, the alternative is a suspended platform.
This job-made rig consists of some sections of scaffold decking and some aluminum ladders hung from the roof. Who determined if it was capable of supporting its own weight
and 4X its maximum intended load?
In some cases, however, even adjustable-suspension scaffolds may not be feasible or safe. When there is no other safe way to reach the work area, a crane or a derrick can provide suspended access by hoisting a personnel platform to reach the work area.
A suspension scaffold is a temporary elevated platform that hangs by wire rope. Add a hoist to move the platform up or down, and you have an adjustable-suspension scaffold - but not necessarily a safe one. Suspension ropes, lifelines, platforms, hoists, overhead support devices, and tieback systems are critical to the safety of adjustable-suspension scaffolds.
How Suspended Scaffold Falls Occur
Most accidents involving adjustable-suspension scaffolds happen when a primary suspension rope breaks. Workers die because they don't use personal fall-arrest systems or they use them incorrectly. Steel suspension ropes rarely break if they're correctly rigged, maintained, and inspected regularly. When the ropes aren't maintained, they weaken. If an ascending platform snags, an electric hoist that continues to operate can easily snap a weak rope. Pressure from the two steel discs that clamp to the support rope in sheave-type hoist motors can also break a weak rope.
Failing anchors also cause serious accidents. Too often, untrained workers attach lifelines and suspension ropes to "secure-looking" rooftop fixtures for convenience. These anchors fail because they aren't designed to support suspended loads.
Lifelines fail because workers hang them over unpadded edges, don't inspect them, or use ropes not designed for personal fall-arrest systems.
Using Adjustable-Suspension Scaffolds
Before you use an adjustable-suspension scaffold, you need to know the engineering principles for anchoring and suspending the scaffold, how to rig the scaffold, how to operate the hoist, how to work safely from the scaffold, and what to do in an emergency.
In addition, a competent person must examine all direct connections that are part of the system and confirm that the connections will support the platform loads. You must also wear a personal fall-arrest system to protect yourself if a connection fails. Most fatal falls from suspended platforms result when a support rope fails and workers aren't wearing personal fall-arrest gear.
Requiring Fall-Protection Systems
If you work on an adjustable-suspension scaffold more than 10 feet above a lower level, you must be protected from falling.
Single-point and two-point adjustable-suspension scaffolds: Personal fall-arrest systems and guardrail systems are required on single-point or two-point adjustable-suspension scaffolds. The top edge of guardrail must be between 36 inches and 45 inches above the platform surface. (The top edge can exceed 45 inches when necessary.)
Boatswain's chairs: Personal fall-arrest systems are required for workers who use boatswain's chairs.
Multipoint adjustable-suspension scaffolds: Personal fall-arrest systems and guardrail systems are required on multipoint adjustable-suspension scaffolds. The top edge of the guardrail must be between 36 inches and 45 inches above the platform surface. (The top edge can exceed 45 inches, when necessary.)
A descent-control device lets you descend a primary support rope - typically from a boatswain's chair - then lock the device when you reach the work area. The device works by friction, engaging the support rope and controlling the descent speed. Most workers start from the roof and work down the face of the building. When they reach the ground, they remove the descent equipment from the support rope and return to the roof for another drop.
How Falls Occur
Most falls result from failure of the primary support rope or a supporting anchor, not the descent device. Support ropes fail because workers don't inspect them regularly or they misuse them. Anchors fail when workers simply assume they are secure. Descent devices, support ropes, and anchors rarely fail when workers know how to use them.
Crane- and Derrick-Suspended Personnel Platforms
How Injuries Occur
Workers rarely fall from suspended personnel platforms. Rather, most accidents happen when the boom or another part of the crane contacts an energized power line. Other causes of serious accidents:
Instability. Unstable ground or support surface causes the crane to tip over.
Lack of communication. The crane operator can't see the suspended platform while it is moving.
Rigging failure. Platform loads are not properly rigged.
Boom failure. The weight of the loaded platform exceeds the boom's load limit.
Safe practices for riding personnel platforms to the work area:
Stay within the platform while it's moving.
Wear a body belt or harness and use a lanyard; attach the lanyard to the lower load block or overhaul ball or to a structural member of the platform.
Stay in view of the crane operator or signal person while you're on the platform.
Before leaving the platform for the work area, secure it to the structure.
Window Washer Rescue
Scaffolds for Compliance Officers
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