Mobile Scaffolds

Rolling towers and baker staging are the most-used and least-inspected access equipment on any site, because they feel like furniture rather than scaffold. Every general scaffold rule in 1926.451 applies to them, plus a specific set in 1926.452(w).

Before anybody gets on

• Casters and wheels locked with positive wheel and swivel locks, or equivalent — 1926.452(w)(2). Both locks, on every caster. A swivel that is free lets the tower walk while somebody is working on it.
• Braced with cross, horizontal or diagonal braces so it cannot rack, and plumb, level and square with every brace connection secured — 1926.452(w)(1).
• On firm level ground. Not on a slope, not on soft fill, not with a caster half on a kerb, and not bridging a floor opening.
• Outriggers where the height calls for them, fitted on all sides.
• Guardrails at 10 feet and above like any other scaffold, and planks that are full width, scaffold grade, and secured against being lifted by wind or a foot.
• Access is the built-in ladder or stairway. Never climb the frame end braces and never lean a ladder against a tower to get up it.

Moving it

This is where the rules people have not read live.

• Push from as close to the base as practicable, and never more than 5 feet above the supporting surface — 1926.452(w)(3). Pushing from up high levers it over.
• Never propel it with a forklift, a truck or an add-on motor unless it is designed for that — 1926.452(w)(4).
• Stabilise it against tipping during movement — 1926.452(w)(5), which in practice means retracting outriggers only if the design allows and taking the load off the deck first.
• Look up before you roll. Power lines, ducts, sprinkler heads, beams, and the lighting.
• Everything comes off the deck. Tools, materials, buckets. Anything left on top becomes a falling object the moment a caster hits a joint in the slab.

Riding it

1926.452(w)(6) allows employees to ride only where all of the following hold, and it is worth reading rather than assuming:

• the surface it is being moved on is within 3 degrees of level and free of pits, holes and obstructions;
• the height-to-base-width ratio during movement is two to one or less, unless it is designed and constructed to meet stability requirements for more;
• outrigger frames, where used, are installed on both sides;
• no power line or obstruction is contacted.

In practice, on a real site with a slab full of joints and cords, that list is rarely all true — which is why the safe default is that everybody gets off before it moves.

And the ordinary ones

Do not overload it, do not use a ladder, box or plank on the deck to gain height, and inspect it before each shift like any other scaffold. A tower with a missing brace pin is a tower that failed already; it just has not fallen yet.