Ladders, scaffolds and elevated work platforms

Most of Maya's work at height is not at a slab edge but a few feet off the floor: hanging pipe from the ceiling, reaching a sleeve in the underside of the slab above, installing a vent at the top of a wall. For this work she uses ladders, rolling scaffolds and, on the high ceilings of the parking levels and the lobby, scissor lifts. These are everyday tools, and that is exactly why they cause so many injuries. People use them without thinking, take shortcuts with them and stand on parts that were never meant to be stood on.

This lesson covers the safe use of each. The principle from lesson 4 still applies: choose the access equipment that removes the most hazard. A platform with guardrails is better than a step ladder, and a step ladder is better than standing on a bucket.

Choosing the right access

Ladders

Falls from ladders are among the most common serious injuries in construction, and OSHA's ladder standard, 1926.1053 in Subpart X, is regularly among OSHA's most cited construction standards. Subpart X requires a stairway or ladder at any point of access where there is a break in elevation of 19 in or more, sets rules for the design and use of ladders, and requires training by a competent person for every worker who uses them. Portable ladders are generally built to ANSI A14 standards. Ladders are best used for access and for short, light work; when a task needs force, both hands or a long time, a platform is the better choice.

Before using any ladder, Maya inspects it: rails straight and uncracked, rungs or steps secure and clean, feet in good condition, locks and spreaders working, labels readable. A damaged ladder is tagged "Do not use" and removed from the work area. She also checks the duty rating on the label. The rating must cover her weight plus her tools and material; most contractors use only heavy-duty ladders rated for at least 250 lb (about 113 kg), and many choose extra-heavy-duty models.

# Where to put the base of an extension ladder (4-to-1 rule)
height_to_support = 12    # vertical height from the ground to where the ladder rests
base_out = height_to_support / 4
extension = 3          # length above the landing
print(f"Set the base {base_out:.2f} ft out from the wall")
print(f"Ladder length needed: at least {((height_to_support**2 + base_out**2) ** 0.5 + extension):.1f} ft")

Set the base 3.00 ft out from the wall
Ladder length needed: at least 15.4 ft

A quick check for the angle that Luis showed Maya: stand at the base with your toes against the ladder's feet and stretch your arms straight out. If your palms just reach the rung in front of you, the angle is about right. It is not precise, but it catches a ladder that is far too steep or too flat.

Kingsway Tower has reduced its ladder use deliberately. The stair towers went in early, so ladders are not used for access between floors, and Stonebridge and Northbridge supply platform ladders with guarded tops for work in the suites. Step ladders are allowed only where a platform ladder will not fit. The change cut ladder incidents on the site to almost none.

Rolling scaffolds

Rolling scaffolds, sometimes called mobile scaffolds or baker scaffolds in their narrow form, are common in interior work. They are quick to set up and move, which is also their danger. OSHA's scaffold standard, Subpart L, requires fall protection on scaffolds where a worker could fall more than 10 ft, requires a competent person to inspect scaffolds before each shift and after anything that could affect their integrity, and requires workers who use scaffolds to be trained by a qualified person. Many contractors require guardrails on baker scaffolds at any height, because a fall from a narrow platform onto a concrete floor can cause serious injury from well under 10 ft.

Many sites use a scaffold tag system: green means the scaffold has been inspected and is ready for use, yellow means it can be used only with special precautions written on the tag (such as a harness because a guardrail is missing for a specific task), and red means do not use. On Kingsway Tower, an untagged scaffold is treated as red. Any change, such as moving a plank or removing a guardrail, makes the scaffold red until a competent person re-inspects it.

Two rules about moving rolling scaffolds catch new workers. First, nobody rides on a rolling scaffold while it is being moved. Second, before moving it, check the route: a floor drain opening, a cord or a small step in the slab can stop a caster dead and tip the whole scaffold. Maya learned to look for overhead obstructions too: sprinkler pipe and ductwork are at exactly the height of the platform.

Scissor lifts and boom lifts

Mobile elevating work platforms (MEWPs), also called aerial lifts, include scissor lifts, which rise straight up, and boom lifts, which reach up and out on an arm. OSHA's aerial lift standard, 1926.453, covers boom-supported lifts and requires workers in the basket to wear a body harness or restraint attached to the boom or basket; scissor lifts are treated as mobile scaffolds, protected by their guardrails. The ANSI A92 standards for MEWPs, published in 2018 and in effect since 2020, require operator training and familiarization on each model, and a rescue plan. Only trained and authorized workers operate lifts.

Maya will not operate a scissor lift until Northbridge trains her and the foreman authorizes her, but she will ride in one with Luis on the parking levels, where the ceilings are high. The daily routine is the same every time: a walk-around inspection of the machine before use, a function test of the controls and the emergency lowering, a check of the floor where they will work for drains and openings, and a look at the ceiling for sprinkler pipe and conduit they could be crushed against.

Working on and around access equipment

Access equipment creates hazards for people below as well as people on it. Tools and fittings can fall from a platform, and a person working on a ladder in a doorway can be knocked off by someone opening the door. Maya's habits include tethering tools at height when working over people or openings, barricading the area below a scaffold or lift when there is a risk of falling objects, and putting a sign or a spotter in doorways and corridors where she has set up a ladder.

Stairs and temporary access

Most falls related to access happen not on ladders or scaffolds but on stairs, ramps and temporary walkways, simply because people use them so often. On a building under construction, stairs may be unfinished concrete or steel pans, without handrails at first, covered in dust or ice, and used by people carrying materials that block their view of their feet.

Maya's habit on stairs is the same as on a ladder, just quicker: one hand on the rail, never carrying a load she cannot see over, and taking long items up in the hoist rather than up the stairs. When she finds debris on a stair tread or a light out in a stairwell, she clears it or reports it the same shift, because the next person on those stairs may be carrying a box of fittings and looking straight ahead.