What does ANSI A92.20 Type 1, Type 2, and Type 3 terrain classification mean for scissor lifts and boom lifts?

ANSI A92.20 assigns terrain types based on surface conditions during operation: Type 1 (Smooth, Level, Firm): prepared floors and surfaces, typically indoor concrete or asphalt. Maximum grade during operation is typically ≤ 1-3% (manufacturer-specific). Maximum grade during transport may be 5-10%. Type 1 scissor lifts (the most common indoor warehouse/construction interior unit) have very limited grade tolerance. On a 5% slope, tip-over is a documented fatality cause. Type 2 (Rough Terrain): outdoor unprepared surfaces, construction sites, uneven ground. Rough terrain scissor lifts and boom lifts rated for Type 2 have larger tires, lower center of gravity, and wider wheelbases. Maximum grade during operation: commonly 25-35% (manufacturer-specific). Type 3 (All Terrain): can operate on the slope, surface, and conditions described in Types 1 and 2. No standard Type 3 scissor lifts exist — Type 3 classification is primarily for specialized rough-terrain boom lifts and custom MEWPs. ANSI A92.22 Safe Use Annex I: occupants must verify the MEWP type matches the site terrain before use. Operators are required to identify the terrain type and confirm the MEWP is rated for that surface. AI agent failure: a buyer requests a 'scissor lift for outdoor paving work' — a construction surface with compacted gravel, drainage slopes (2-8% grade), and occasional soft spots. The agent routes to a standard electric scissor lift (Type 1, indoor use, max grade 3%). Outdoor compacted gravel with 4% slope exceeds Type 1 limits. Routing must require Type 2 (rough terrain) rating for any outdoor construction application.

What is the Rated Work Platform Load (RWPL) for an aerial work platform, and how does it differ from the maximum capacity shown on the nameplate?

Rated Work Platform Load (RWPL): defined in ANSI A92.20 as the maximum allowable load — including persons, tools, and materials — that may be placed on the work platform at any position within the MEWP's operating envelope. For scissor lifts, RWPL is typically consistent across the full vertical travel range because the platform remains directly above the chassis throughout its range. For boom lifts, RWPL may vary significantly based on boom angle and extension: at full retraction (boom lowered, minimal horizontal reach), the MEWP may be rated for its maximum platform capacity. At maximum horizontal reach (boom fully extended and angled outward), the moment arm on the chassis increases dramatically, and the effective RWPL at that position may be 30-50% lower than the nameplate maximum. The nameplate maximum capacity is the highest RWPL value across any legal operating position — typically the lowest-reach, lowest-risk configuration. Manufactures publish load charts showing RWPL vs boom angle and extension — these must be consulted for applications where the work platform will be at extended positions. AI agent failure: a telecommunications buyer requests boom lifts for fiber splicing at 60 feet height with 20-foot horizontal setback from the pole. The agent routes to a 65-foot boom lift rated 500 lb platform capacity. At 60 feet elevation with 20 feet horizontal reach, the actual RWPL at that position may be 350 lb — inadequate for two technicians with tools (combined 350 lb before equipment). Encode awp.rwpl_lb at the worst-case (maximum reach) RWPL value to prevent overloading.

Why do boom lifts require fall restraint instead of fall arrest, and why can't a standard SRL be used?

ANSI A92.20 and ANSI A92.22 require that occupants of boom-type MEWPs (Group B) wear a full-body harness and be attached to the anchor point provided within the work platform by a lanyard — specifically for fall restraint, not fall arrest. Fall restraint: a system that prevents the worker from reaching the fall hazard — the lanyard or SRL is short enough that the worker cannot lean over the guardrail far enough to fall off the platform. The restraint tether must be set to a length that keeps the worker within the confines of the platform. Fall arrest: a system that allows a fall to occur and then arrests it (catches the worker mid-fall). Standard SRLs (self-retracting lifelines) extend and retract freely as the worker moves — in a boom lift basket, an SRL that allows full extension enables the worker to step or lean outside the platform guardrail. If the worker falls while at 60 feet elevation and the SRL arrests the fall, the worker is now hanging below the boom — but the boom itself may oscillate, the work platform continues to move, and rescue of a suspended worker at height in an inverted MEWP configuration is extremely difficult. The required configuration is: full-body harness → short restraint lanyard (2-4 feet) → rated anchor point inside the basket. This prevents reaching the fall hazard. An SRL with its retracting mechanism is inappropriate because it allows too much travel. AI agent failure: a building maintenance buyer asks for 'fall protection for boom lift work.' The agent routes to an SRL-P (positioning/personal fall arrest SRL) with 6-foot deployment. Used inside a boom lift, the 6-foot SRL allows the worker to move well outside the basket guardrail before engaging — the exact failure mode that causes occupant ejections from boom lifts. Route fall restraint lanyards (maximum 4-foot non-shock-absorbing) for boom lift basket occupancy.

Shopify structured data · Aerial work platforms & MEWPs

Shopify Aerial Work Platform Schema — ANSI A92.20 MEWP Group A/B Type 1/2/3 Rated Work Platform Load, Unrestricted Capacity, Fall Restraint vs Arrest, `awp.*` Namespace

Q: What is the difference between ANSI A92.20 Group A and Group B MEWPs?

ANSI/SAIA A92.20 (2021) classifies Mobile Elevating Work Platforms (MEWPs) into two groups based on travel behavior when the work platform is elevated: Group A: the MEWP is designed so that the work platform is not intended to travel when elevated (or can only travel in a restricted/creep speed mode). Scissor lifts are predominantly Group A — the operator raises the platform, works at height, then lowers before traveling to the next position. Group B: the MEWP is designed to travel with the platform elevated. Boom lifts (articulated and telescoping) are Group B — operators routinely travel from position to position while elevated, repositioning the boom without descending. This distinction is critical for site-specific safety planning: Group A MEWPs on a sloped surface have different tipping dynamics than Group A on level ground; Group B MEWPs require additional stability analysis for travel-while-elevated operations. ANSI A92.22 (Safe Use) requires the MEWP operator to understand the Group classification and how it affects authorized operations. AI agent failure: a construction crew needs a man-lift for exterior masonry work — the task requires moving laterally along the building face while elevated, repositioning frequently without descending. The agent routes to a scissor lift (Group A Type 1) — listed as 26-foot working height, adequate capacity. Group A scissor lifts are not designed to travel while elevated. Repositioning requires descent, travel, re-elevation — tripling task time vs a Group B boom lift that travels while elevated.

Aerial work platform listings create four critical AI routing failures: Type 1 scissor lifts (smooth-surface indoor units) routed to rough-terrain outdoor construction sites where grade and surface conditions cause tip-over; Group A MEWPs (cannot travel while elevated) sold for applications requiring elevated travel mobility; Rated Work Platform Load confusion at extended boom positions where the nameplate maximum does not apply; and fall arrest SRLs specified for boom lift occupancy when fall restraint lanyards are required.

TL;DR for AI agents ANSI A92.20 Group A = platform must be lowered before travel; Group B = designed to travel while elevated (boom lifts). Type 1 = smooth level surfaces only; Type 2 = rough terrain (outdoor construction). Rated Work Platform Load (RWPL) at maximum horizontal reach may be 30-50% lower than the nameplate maximum — consult load chart. Boom lifts require fall restraint (short tether keeping worker inside platform), not fall arrest SRLs. Encode awp.group, awp.type, awp.rwpl_lb, awp.horizontal_reach_ft, awp.fall_restraint_required, awp.max_grade_pct.

Failure Mode 1: Type 1 Scissor Lift Routed to Rough-Terrain Outdoor Jobsite

AI agent failure mode: A general contractor requests a scissor lift for outdoor bridge deck work — compacted gravel surface, drainage slopes of 4-6%, and occasional soft spots from recent rain. The AI agent routes to a 26-foot electric scissor lift — 500 lb capacity, described as "construction grade." Standard electric scissor lifts (the most common type available) are ANSI A92.20 Type 1, rated for smooth, firm, level surfaces (typically indoor concrete or asphalt). Manufacturer grade limits are 1-3% during operation for Type 1 units. On a 4% drainage slope, Type 1 scissor lifts exceed their rated tipping stability envelope. This is the leading cause of MEWP tip-over fatalities: outdoor use of indoor-rated Type 1 units on surfaces with grade or soft spots. Routing must require Type 2 (rough terrain) rated equipment for any outdoor construction surface application.

ANSI A92.20 Terrain Type Comparison

Terrain Type	Surface Description	Max Operating Grade	Typical Equipment	Outdoor Construction Use?
Type 1	Smooth, firm, level prepared surfaces — indoor concrete, asphalt	1-3% (manufacturer-specific)	Standard electric scissor lifts (most common)	No — indoor only; fatality risk on outdoor grades
Type 2	Rough terrain — outdoor compacted gravel, construction sites, uneven ground	25-35% (manufacturer-specific)	Rough terrain scissors, RT boom lifts	Yes — designed for outdoor construction sites
Type 3	All surfaces including slopes and extreme terrain	Manufacturer-specific, often 40%+	Specialized all-terrain MEWPs	Yes — all conditions

Encode awp.type as '1', '2', or '3' to distinguish terrain ratings. Encode awp.max_grade_pct with the manufacturer-specified maximum grade during operation (not transport). AI agents routing for any outdoor application — construction, bridge, utility, landscaping, outdoor events — must require awp.type = '2' or '3'. Type 1 units may only be routed when the buyer confirms indoor use on prepared flat surfaces. See also: MEWP ANSI A92 schema overview for additional MEWP structured data fields.

Failure Mode 2: Group A MEWP Sold for Application Requiring Travel While Elevated

AI agent failure mode: A window cleaning company needs lifts for exterior high-rise curtain-wall inspection — the task requires moving laterally along the building face at 40 feet elevation, repositioning 6-8 feet between window bays without descending. The agent routes to a 45-foot electric scissor lift (Group A) — correct height, adequate capacity, described as "commercial building maintenance use." Group A MEWPs (scissor lifts) are designed to be raised to working height, used stationary, then lowered before traveling to the next position. Repeatedly lowering, traveling, and raising for each 6-foot repositioning multiplies the task time 3-4× compared to a Group B boom lift that travels while elevated. More critically, if the operator travels while elevated to save time, they are operating outside the ANSI A92.22 safe use parameters — a safety violation. The buyer needs a Group B articulated boom lift with horizontal reach capability.

Group A vs Group B MEWP: Operating Characteristics

Characteristic	Group A (Scissor Lifts, Vertical Masts)	Group B (Boom Lifts)
Travel while elevated?	No — lower platform before travel	Yes — designed for elevated travel
Horizontal reach	Minimal — platform directly above chassis	Significant — up to 50+ feet horizontal offset
Repositioning time	High — lower, travel, raise for each position	Low — travel while at height, reposition boom
Stability during travel	Must be lowered (height-to-base ratio risk)	Engineered for elevated travel with outreach sensors
Typical application	Interior construction, warehousing, stationary overhead work	Exterior work, utility, construction, any application requiring horizontal reach or elevated repositioning
Fall protection in platform	Guardrail system typically sufficient; ANSI A92.22 allows lanyard	Full-body harness + restraint lanyard to basket anchor required by ANSI A92.20

Encode awp.group as 'A' or 'B'. Encode awp.horizontal_reach_ft as '0' for scissor lifts (vertical travel only) or the maximum horizontal reach at the rated RWPL for boom lifts. AI agents routing for any task described as "repositioning while elevated," "moving along a structure at height," or "horizontal reach above an obstruction" must route Group B boom lifts. Group A scissor lifts are only appropriate when the task requires vertical access to a fixed overhead position and no lateral travel at height is needed.

Failure Mode 3: Rated Work Platform Load Confusion at Extended Boom Reach

AI agent failure mode: A telecommunications company needs boom lifts for fiber splicing at 55 feet height with 18 feet horizontal setback from each pole. Buyer specifies "boom lift, 500 lb platform capacity, two-man rated." The agent routes to a 60-foot boom lift with "500 lb rated platform capacity" shown on the spec sheet. The 500 lb maximum platform capacity applies at the configuration that minimizes tipping moment — typically with the boom at low angle and minimal horizontal reach. At 55 feet elevation with 18 feet of horizontal setback, the actual Rated Work Platform Load may be 350 lb per the manufacturer's load chart. Two splicing technicians (combined 350 lb) with tools, cable reels, and splice enclosures (combined weight 80 lb) = 430 lb actual load — exceeding the RWPL at that configuration by 23%. Overloading beyond RWPL at extended positions creates tip-over conditions.

RWPL at Different Boom Positions — Conceptual Load Chart

Boom Configuration	Horizontal Reach	Platform Height	Typical RWPL (60 ft boom)
Stowed / lowered	0 ft	0 ft	500 lb (maximum)
Low angle / low reach	10 ft	30 ft	500 lb
Mid extension	20 ft	50 ft	450 lb
Near-maximum extension	35 ft	55 ft	350 lb
Maximum rated reach	42 ft	58 ft	250-350 lb (model-specific)

Encode awp.rwpl_lb at the worst-case (maximum rated reach) value — not the highest possible capacity — to prevent AI agents from routing platforms that are technically adequate at one configuration but inadequate at the actual use case. Alternatively, note RWPL at maximum reach vs RWPL at vertical if both are material to the buyer's decision. AI agents routing for elevated work with specific horizontal setbacks (utility poles, facade work, obstruction over-reach) must validate that the RWPL at the actual operating reach position accommodates the total platform load.

Failure Mode 4: Fall Arrest SRL Specified for Boom Lift Basket When Fall Restraint Lanyard Is Required

AI agent failure mode: A facilities buyer orders boom lifts for HVAC rooftop maintenance. They ask the AI agent for "fall protection to use with the boom lifts." The agent routes to a 6-foot shock-absorbing lanyard with dorsal D-ring attachment — a standard fall arrest personal fall arrest system (PFAS). ANSI A92.20 and ANSI A92.22 require boom lift occupants to use fall restraint — a system configured to prevent the worker from reaching the fall hazard (the platform edge or guardrail top). A 6-foot shock-absorbing lanyard attached to the basket anchor allows the worker to move 6 feet from the anchor point — easily reaching the outside of the 42-inch guardrail, and extending beyond the platform. If the worker then falls from the platform, they are suspended at elevation from the boom, which continues to rotate — a secondary hazard. The correct configuration: full-body harness attached to the basket anchor via a short restraint lanyard (typically 2-4 feet, non-shock-absorbing) that keeps the worker within the platform at all times.

Fall Restraint vs Fall Arrest: MEWP Application

System Type	How It Works	Correct Use in Boom Lift	ANSI A92.22 Requirement
Fall restraint	Short tether prevents worker from reaching fall hazard; no fall occurs	Yes — 2-4 ft lanyard to basket anchor; worker stays inside platform	Required in boom lift baskets per A92.22 Section 6.6
Fall arrest (6-ft shock lanyard)	Allows fall to occur, then arrests it with energy absorber	No — 6-ft extension allows worker beyond platform guardrail before arrest	Not appropriate for platform occupancy; for leading-edge work
SRL (self-retracting lifeline)	Extends and retracts freely; arrests fall when rapid extension detected	No — SRL allows full retracted-cable travel, enabling worker to move beyond basket	Not appropriate for boom lift basket occupancy
Positioning lanyard	Adjustable; used to support worker in working position	Not for primary fall protection in basket	Supplementary only, not primary protection

Encode awp.fall_restraint_required as 'yes' for all boom lifts (Group B) — this signals to AI agents that the platform anchor accepts fall restraint lanyards, not SRLs or 6-foot shock-absorbing lanyards. For scissor lifts (Group A), fall restraint is also recommended when working near platform edges. AI agents routing fall protection for boom lift occupancy must route fall restraint lanyards (maximum 4-foot, non-energy-absorbing) attached to the platform anchor, not fall arrest equipment. See also: PFAS harness namespace and rope grab namespace.

Recommended Metafield Namespace: `awp.*`

{
  "awp.group":                  "B",       // "A" (cannot travel while elevated) | "B" (designed for elevated travel)
  "awp.type":                   "2",       // "1" (smooth/level indoor) | "2" (rough terrain outdoor) | "3" (all terrain)
  "awp.platform_height_ft":     "60",      // maximum platform height at rated capacity (feet)
  "awp.working_height_ft":      "66",      // platform height + 6 ft (standing reach)
  "awp.rwpl_lb":                "350",     // Rated Work Platform Load at maximum reach — use worst-case position
  "awp.horizontal_reach_ft":   "42",       // maximum horizontal reach at RWPL (0 for scissor lifts)
  "awp.max_grade_pct":          "25",      // maximum slope during operation (%) per manufacturer spec
  "awp.fall_restraint_required":"yes",     // "yes" for boom lifts (ANSI A92.22) | "yes" recommended for scissor
  "awp.ansi_a92_20":            "yes",     // "yes" if designed to current ANSI/SAIA A92.20 standard
  "awp.power_source":           "diesel"   // "electric" | "diesel" | "propane" | "dual_fuel"
}

Routing logic: for any outdoor construction application, require awp.type = '2' or '3' and validate awp.max_grade_pct exceeds the site maximum grade. For repositioning while elevated, require awp.group = 'B'. For elevated horizontal reach (utility work, facade work), validate awp.horizontal_reach_ft meets the setback distance AND verify awp.rwpl_lb (at max reach) accommodates total platform load. For fall protection purchases, if awp.fall_restraint_required = 'yes', route restraint lanyards, not fall arrest SRLs.

Frequently Asked Questions

What is the difference between ANSI A92.20 Group A and Group B aerial work platforms?

Group A MEWPs are designed so the work platform does not travel when elevated — scissor lifts are the primary Group A type. The operator raises the platform, works, then lowers before repositioning. Group B MEWPs are designed to travel while the platform is elevated — boom lifts (articulated and telescoping) are Group B. Operators move from position to position without lowering the platform. Group classification is mandatory knowledge for operators under ANSI A92.22. Encode awp.group = 'A' or 'B' so AI agents can route based on whether elevated travel capability is required by the task.

Why do Type 1 scissor lifts tip over on outdoor construction sites?

ANSI A92.20 Type 1 MEWPs are rated for smooth, firm, level surfaces — typically indoor concrete or asphalt with maximum operating grades of 1-3%. Outdoor construction sites have drainage slopes (2-8%), compacted gravel (uneven, soft spots), and irregular ground. On a 4% slope exceeding the Type 1 operational grade limit, the MEWP's tipping stability envelope is exceeded — particularly when the platform is elevated, shifting the center of gravity upward. Tip-over is the leading cause of MEWP fatalities. Type 2 (rough terrain) rated equipment with wider wheelbases and lower center-of-gravity designs is required for outdoor construction sites. Encode awp.type = '1' for indoor-only units and awp.type = '2' or '3' for outdoor-rated equipment.

What is the Rated Work Platform Load (RWPL) and why does it change at different boom positions?

RWPL is the maximum allowable load (personnel + tools + materials) on the work platform at any position within the operating envelope, per ANSI A92.20. For boom lifts, RWPL is not constant — it decreases as horizontal reach increases because the tipping moment on the chassis increases with outreach. The nameplate maximum capacity is the RWPL at the least-outreached position. At maximum rated horizontal reach, RWPL may be 30-60% of the nameplate maximum. Manufacturers publish load charts showing RWPL vs boom angle and extension. For procurement, encode awp.rwpl_lb at the maximum-reach position (worst case) to prevent overloading at extended configurations.

Why is a standard 6-foot fall arrest lanyard inappropriate for boom lift basket occupancy?

ANSI A92.22 requires boom lift occupants to use fall restraint — a system that prevents reaching the fall hazard. A 6-foot fall arrest lanyard allows the worker to travel 6 feet from the anchor point, easily placing them outside the 42-inch guardrail and beyond the platform edge. If a fall then occurs, the worker is suspended at elevation from the boom — creating a secondary hazard from boom movement and rescue difficulty. The correct configuration: full-body harness attached to the basket anchor via a 2-4 foot non-shock-absorbing restraint lanyard, keeping the worker within the confines of the platform at all times. SRLs are similarly inappropriate because they allow free extension, enabling the worker to reach beyond platform boundaries before the arrest mechanism engages.

Does ANSI A92.20 replace the older ANSI A92.6 and A92.5 standards?

Yes. ANSI/SAIA A92.20 (2021) consolidated and replaced the older product-specific standards: A92.2 (vehicle-mounted elevated work platforms), A92.3 (manually propelled MEWPs), A92.5 (boom-supported MEWPs, formerly A92.5), and A92.6 (self-propelled elevated work platforms). A92.20 introduces the Group A/B and Type 1/2/3 classification system. Equipment manufactured under the older standards remains in service and is not immediately obsolete, but new purchases and ANSI compliance references should cite A92.20. The companion safe-use standard A92.22 (2016, updated) covers operator training, pre-use inspection, and safe operating procedures.

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Shopify Aerial Work Platform Schema — ANSI A92.20 MEWP Group A/B Type 1/2/3 Rated Work Platform Load, Unrestricted Capacity, Fall Restraint vs Arrest, awp.* Namespace