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.
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.
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:
Before workers use ladders, a competent person must train them so that they understand the following:
Keep the following in mind when you use a portable ladder:
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.
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.
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:
Minimum clearance distances:
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:
Most accidents involving aerial lifts can be traced to untrained or improperly trained workers. Reasons for falls:
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.
Keep in mind the following when you use an aerial lift:
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.
Suspended access is a means of getting to difficult-to-reach work areas on a suspended platform. Usually the platform is an adjustable-suspension scaffold. The scaffold, typically suspended by wire rope from a rooftop anchor, has a hoist that workers use to reach the work area.
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.
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.
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.
If you work on an adjustable-suspension scaffold more than 10 feet above a lower level, you must be protected from falling.
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.
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.
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:
Safe practices for riding personnel platforms to the work area:
On August 17, 1998, a 15-year-old window washer's helper (the victim) died after falling 40 feet from the roof of a medical office building. The helper was stationed on the roof to move a window washing carriage and assist the window washer, who worked from a boatswain's chair as he cleaned the windows of the 4-story building.
On the afternoon of the incident, the window washer seated himself in the boatswains' chair and positioned himself over the edge of the roof's parapet. He then "bounced" in the boatswain's chair to make sure it was set to go. Because the carriage was not tied down and did not have counterweights attached, the carriage was pulled over the rooftop's parapet. Both workers had their fall arrest harnesses secured to the carriage. The window washer fell straight down while the helper was pulled from the roof by the carriage and struck the ground head-first. The local emergency medical unit was summoned immediately. The window washer's helper died from his injuries at the scene and the window washer suffered multiple severe injuries.
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