These type-specific rules apply on top of 1926.451; scaffolds not named here, such as systems scaffolds, must still meet 1926.451. Pole scaffolds (a): leave the old platform in place until new bearers are set and braced; crossbrace between inner and outer pole rows on double pole scaffolds; diagonal bracing both ways across the whole inside face of double pole scaffolds carrying 50 pounds per square foot or more, and across the whole outside face of all single and double pole scaffolds; runners and bearers on edge; bearers extending at least 3 inches beyond runners; runners spanning at least two poles on bearing blocks; no splicing of braces, bearers or runners between poles; wood pole splices squared with plates on at least two sides extending 2 feet each way; a registered professional engineer designs any pole scaffold over 60 feet. Tube and coupler (b): same platform-moving rule; X transverse bracing at the ends and at least every third set of posts and every fourth runner vertically; longitudinal diagonal bracing at about 45 degrees, repeated from at least every fifth post on long runs; bearer, runner and coupler placement rules; couplers of structural metal, never gray cast iron; engineer design over 125 feet. Fabricated frame (c): braced to stay plumb, level and square, frames joined vertically by pins and locked where uplift can occur, cantilever brackets seated correctly and used for personnel only unless a qualified engineer designed them for other loads; engineer design over 125 feet above base plates. Plasterers', decorators' and large area scaffolds (d) follow (a), (b) or (c). Bricklayers' squares (e): gussets, diagonal bracing, three tiers maximum. Horse scaffolds (f): capped at two tiers or 10 feet, whichever is less, stacked directly, legs secured and each tier crossbraced. Form and carpenters' bracket scaffolds (g): brackets attached by the listed means; folding metal brackets bolted or pinned. Roof brackets (h) fit the pitch and are nailed, or where nails are impractical held by 3/4 inch or thicker first-grade manila, or equivalent. Outrigger scaffolds (i): inboard length at least 1.5 times outboard, web vertical, fulcrum bearings at least 6 inches each way, braced, anchored and engineer designed. Pump jacks (j): metal brackets with two positive grips, poles braced (an extra brace about 4 feet above one being passed), workbenches never used as platforms and only as a toprail if they meet the listed 1926.451(g)(4) items, wood pole quality and splicing rules. Ladder jacks (k): platforms no higher than 20 feet, Subpart X ladders but not job-made ones, at least 10 inches of bearing on each rung where the jack bears on rungs only, anti-slip measures, no bridging. Window jacks (l) are secured and used only at their own opening. Crawling boards (m) run peak to eaves, held by ridge hooks or equivalent. Step, platform and trestle ladder scaffolds (n): platform set no higher than the next-to-top rung or step, no job-made ladders, no bridging. Single-point adjustable (o): combined units follow (p); supporting rope kept vertical unless qualified person rigging, rescue access, chafe protection and no swing contact are all in place; boatswains' chair tackle and slings at least 5/8 inch rope, or 3/8 inch wire rope near heat-producing work. Two-point (p): platforms no wider than 36 inches unless a qualified person designs them; light-metal platforms rated at 750 pounds or under, and platforms 40 feet long or shorter, need testing and listing by a nationally recognized laboratory; no bridging while raising or lowering unless articulated with properly sized hoists; passage only at equal height with walk-through stirrups. Multi-point (q): bridging only where designed and articulated. Catenary (r): one platform between pickups, at most two platforms, hook stops, no splices. Float (s): at least two bearers projecting 6 inches each side. Interior hung (t): supports inspected for strength before erection. Needle beam (u): beams on edge, ropes or hangers securely attached, platform units bolted or equivalent (cleats and overhang do not count). Multi-level (v): independent support lines matching the suspension ropes in count and strength, on separate anchorages, with platform supports fixed to the stirrup. Mobile (w): braced, casters locked when stationary, pushing force no higher than 5 feet, workers ride only if the surface is within 3 degrees of level, the ratio is 2:1 or less (unless tested for stability), outriggers on both sides, powered speed not over 1 foot per second and nobody beyond the wheels; everyone warned before a move. Repair bracket (x): securing wire ropes of 1/2 inch diameter or more (5/16 inch minimum for fall arrest anchorage ropes), turnbuckles at least 1 inch, no U-bolt clips, no materials dropped outside, erection in one direction. Stilts (y): only on large area scaffolds, guardrails raised by the stilt height, clear flat surfaces, maintained with manufacturer-approved alterations.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.