Changes in Level

Curb ramps complying with 4.7 are required wherever an accessible route crosses a curb.

The running slope of curb ramps cannot exceed 1:12. In alterations where it is technically infeasible to meet new construction requirements, curb ramps may have a maximum slope of 1:10 if the rise does not exceed 6 inches. It is important that transitions to curb ramps be flush. Lips at the bottom of ramps, a common complaint, impede the momentum needed to propel a wheelchair up-slope. Severe counter slopes can do the same thing and cause footrests to scrape. Recommendation: While a 5% adjoining slope is allowed for drainage, gutters, and roadway crowns, this slope should be minimized wherever possible (a maximum 2% slope is preferred).

The minimum clear width of a curb ramp is 36 inches, exclusive of flared sides. Curb ramp surfaces, including flared sides, must comply with requirements in 4.5 for ground and floor surfaces be "stable, firm, and slip resistant." The cross-slope of the curb ramp (2% maximum) must be minimized because it makes wheelchair travel difficult by distributing weight and required force to one side and causing front casters to veer.

Where pedestrians cross the ramp, curb cuts are required to have side flares; sharp returns present tripping hazards. Returned curbs are acceptable where pedestrian traffic across the ramp is discouraged.

Built-up curb ramps are permitted where they do not project into vehicular traffic lanes or access aisles at parking spaces and passenger loading zones. (The surface of access aisles cannot slope more than 2% in any direction). Recommendation: Curb ramps with returned sides or concave flares are preferred over built-up curb ramps with convex flares because they provide greater edge protection.

The edges of curbs can provide a cue to people with vision impairments. Since curb ramps remove this detectable drop-off, ADAAG originally required a distinctive dome patterning for the surface of curb ramps detectable by canes or by foot so that people with vision impairments could detect the transition from pedestrian area to street. In response to business and user concerns about the need and specifications for this detectable warning, this requirement was suspended in 1994 pending further study. Alternative means of providing a tactile warning at curb ramps that empty into streets may be acceptable (though not required) until a requirement may be established. Jurisdictions may continue to install the truncated domes specified in ADAAG or other surfaces or technologies if they wish but are not obligated to do so.

It is important that parked cars, lampposts, utility poles, and other elements placed along sidewalks not obstruct connecting accessible routes. Space is needed at the top and bottom of ramps so that people using wheelchairs can align with the running slope and maneuver from ramps, including when making turns (which is difficult on sloped surfaces). At curb ramps, a landing provides the necessary connection to an accessible route. A landing with a minimum length of 48 inches will provide sufficient turning space. Where space at the top is less than 48 inches, side flares must have a maximum slope of 1:12 instead of 1:10 at the curb face.

Alternative designs can plrovide sufficient landings at ramps where space is limited, including at intersections. Perpendicular ramps that are offset from the intersection can provide level landings at the top and bottom of ramps.

The foot of a curb ramp must be contained within the crosswalk, where one is marked. At corners with a large radius, perpendicular curb ramps should be located so that the centerline is radial to the curb face instead of being in line with the crosswalk direction.

People using wheelchairs should not be directed into an active travel lane in order to cross stopped traffic. A landing at least 48 inches long must be provided outside the through-travel lanes if a diagonal ramp is used. Otherwise, perpendicular curb ramps should be used. In addition, a segment of straight curb at least 2 feet long must be provided on each side of the curb ramp and within the marked crossing.

At traffic islands, wheelchair space between opposing ramps is essential. If there is no level space between ramps, wheelchairs can "bottom out" or "high center" while proceeding down one ramp while the back wheels are coming up the other slope. Cut-through routes level with the street are necessary where wheelchair space between opposing ramps is not available. Islands with cut-through routes must be wide enough (48 inches minimum) to provide space for a person using a wheelchair.

Where the running slope of an accessible route is more than 5%, it is considered a ramp. Generally, changes in level up to 6 inches can be treated as a curb ramp.

Curved ramps, while not specifically addressed by ADAAG, are not considered suitable for wheelchair traffic unless the radius of curvature is large enough. The curvature and slope typically result in an uneven surface that makes wheelchair maneuvering difficult because not all wheels rest on the surface. An inner radius of curvature over 30 feet is considered necessary in order to minimize the slope differential.

Slope represents the proportion of vertical rise to horizontal length and can be represented as a ratio (as in ADAAG), percentage, pitch or in degrees.

rise: length	percent	pitch	degree
1:8	12.50%	.1250	7.13
1:10	10%	.1000	5.71
1:12	8.33%	.0833	4.76
1:13	7.69%	.0769	4.40
1:14	7.14%	.0714	4.09
1:15	6.67%	.0667	3.81
1:16	6.25%	.0625	3.58
1:17	5.88%	.0588	3.37
1:18	5.55%	.0555	3.18
1:19	5.26%	.0526	3.01
1:20	5.00%	.0500	2.86
1:50	2.00%	.0200	1.15

Slope and length greatly determine a ramp's usability. There are trade-offs between the two: a steeper slope makes the run shorter, while a more gradual slope increases the length. A maximum slope of 1:12 is specified although ADAAG calls for the "least possible" slope to encourage more gradual slopes which better serve children and people with limited stamina or upper body strength. A recent study by the Access Board ("Technical Requirements for Ramps" (1996) by the Center for Accessible Housing) indicates a significant increase in exertion occurs on ramps with slopes 1:14 or steeper. Recommendation: Consider slopes between 1:16 and 1:20 as preferred, especially at ramps with long runs. The slope should be consistent along the full length of the run. Variation above regular construction tolerances can be disruptive to wheelchair travel, especially in the ascent direction.

Steeper slopes are allowed for short ramps where a 1:12 slope is not technically feasible.

altered facilities (including historic)	max rise 3 inches	max slope 1:8
altered facilities (including historic)	max rise 6 inches	max slope 1:10
qualified historic structures only	max rise 4 inches	max slope 1:6

The maximum length of a run is determined by the rise (30 inches maximum) and the slope:

max rise 30 inches	slope 1:12	max length 30 feet
max rise 30 inches	slope 1:13	max length 32.5 feet
max rise 30 inches	slope 1:14	max length 35 feet
max rise 30 inches	slope 1:15	max length 37.5 feet
max rise 30 inches	slope 1:16	max length 40 feet
max rise 30 inches	slope 1:17	max length 42.5 feet
max rise 30 inches	slope 1:18	max length 45 feet
max rise 30 inches	slope 1:19	max length 47.5 feet

The number of runs per ramp is not limited although the more runs a ramp has the less usable it is. While intermediate landings offer resting points, they do not reduce the amount of force people using wheelchairs must exert traveling up ramps.

The minimum clear width for ramps of 36 inches is measured between the leading edge of handrails. A maximum clear width is not specified. Recommendation: It is often advisable that ramps be wider than the minimum required where usage of the ramp may be subject to appreciable pedestrian traffic.

Landings at the top and bottom and intermediate landings, must be at least 60 inches long so maneuvering space is available for approaching ramps straight on. Landings must be at least as wide as the ramp they serve and cannot slope more than 2% in any direction. Where ramps change direction, the landing must be at least 60 by 60 inches. This applies to switchback ramps, ramps with a 90 degree turn, and angled ramps. Recommendation: Ramps and landings should be configured to facilitate maneuvering. For example, runs should be aligned along the outside landing edge, as in the case of ramps with a 90 degree turn, so that a wider turn is permitted. Handrail extensions can wrap around landings. It is recommended that landings of exterior ramps be drained so that water does not accumulate on the surface.

Landings must provide the maneuvering clearance at doors required in ADAAG 4.13. ADAAG does allow the landing to overlap maneuvering clearances at doors. Recommendation: Ramps and doors should be configured to facilitate wheelchair maneuvering and to prevent open doors from obstructing ramp openings (important along egress routes). Keeping the door swing clear of minimum landing dimensions is a good idea, especially at the bottom of ramps since people using wheelchairs may exit them with some force and speed.

Recommendation: Stairs that open onto ramp landings should be configured so that a person using a wheelchair is not required to maneuver close to the stair opening. Consider allowing additional space beyond the minimum maneuvering clearance required at doors and/or locating stair openings away from the accessible route connecting doors and ramps.

Handrails are required on both sides for ramps with a rise more than 6 inches or a horizontal length more than 72 inches. They are not required along ramps adjacent to seating in assembly areas.

ADAAG shows a diameter of 1� to 1� inch for handrails. A standard IPS pipe designated as 1� to 1� inch is acceptable. Since 1� inch pipe has an outside diameter close to 2 inches, it is important that handrails mounted to walls still provide the 1� inch (absolute) knuckle clearance. This clearance allows space for knuckles while preventing entrapment for people who lean on rails with their forearm. Handrails can be mounted to guardrails or on top of walls consistent with ADAAG specifications. The height of a guard rail (to prevent falling off the edge) is not specified by ADAAG; local building codes do, however, commonly regulate the minimum height of a guardrail at 42 inches. Because, in ADAAG, the maximum height of a handrail is 38 inches, a handrail must be installed in addition to the guardrail.

Handrails that are not continuous must have horizontal extensions at both the top and bottom of the ramp at least 12 inches long that are rounded or returned smoothly to wall, posts, or floors. Inner handrails on switchback ramps must be continuous. Handrails extensions are required on all new ramps but need not project into perpendicular circulation paths in alterations. ADAAG (Figure 17) illustrates returns to post that comply as protruding objects.

The cross slope (2% maximum) must be minimized because it makes wheelchair travel difficult by distributing more weight and required force to one side and causing front casters to veer. Ramp surfaces must comply with requirements for ground and floor surfaces in 4.5 and be "stable, firm, and slip-resistant." A specific level of slip-resistance is not mandated. It is difficult to categorize various materials as acceptable or unacceptable since surface treatments (texturing and applied coatings) can make a considerable difference. Recommendation: It is important that consideration be given to the conditions likely to be found on the surface, such as providing a higher level of slip-resistance on surfaces exposed to moisture.

Handrails alone do not necessarily provide effective edge protection for people who use wheelchairs, crutches, and other mobility aids. Curbs (or walls) are effective in keeping both wheelchairs and crutch-tips from slipping off the edge or getting caught on vertical posts. Horizontal rails are another alternative although mounting heights are not specified (the 27 inch height in ADAAG Figure 17 pertains to the return of extensions as protruding objects). A rail mounted close enough to the ramp surface to prevent passage of a 4 inch diameter sphere can function like a curb in keeping front casters from getting stuck on vertical posts and crutch-tips from slipping off the edge.

Vertical balusters can be used; intermediate spacing is not specified by ADAAG but is commonly covered by local codes. Curbs, horizontal rails, or extended platforms can help prevent crutch-tips from slipping off the edge between rails. Extended platforms, a permitted alternative, can keep crutch tips from slipping over the edge (but might not keep wheelchair casters from getting caught on vertical posts unless horizontal or vertical guard rails are also provided).

Exterior ramps must be designed so that water does not accumulate on the ramp or landing surface. A slope up to 2% is allowed at landings for adequate drainage. Wetness reduces slip resistance, which is fully characterized not only by the ramp or floor surface but by the material making contact with it. Puddling that causes shoes, wheels, or crutch tips to become wet will reduce slip resistance even where the ramp surface is dry. Water accumulation is a particular hazard where it can turn to ice. Covering ramps with a canopy or roof is not required but should be considered where wet or snowy conditions are likely.

Specifications in 4.9 benefit people who have difficulty walking or using stairs. Compliance is required where stairs are the only connection between two levels, such as between floors in buildings without elevators. Stairs do not have to comply where vertical access (ramp, elevator, or lift) is provided. In this case, compliance is still a good idea since some people with walking impairments may prefer stairs to ramps or wheelchair lifts. Also, most building codes require stairs to comply with similar requirements. Where compliance is required, 4.9 applies to all stairs between levels not connected by an accessible means.

Stairs are not considered part of an accessible route but where they are required to comply with 4.9, it is recommended that routes to them meet the requirements for accessible routes since certain specifications, such as clear width, can benefit people with walking impairments able to use stairs and those who use service animals.

ADAAG does not specify the minimum number of steps that comprise a set of "stairs." Most building codes require handrails for a certain change in level or number of steps. (In new construction, the requirement for accessible routes usually makes compliance with 4.9 optional).

The requirement for a minimum 48 inch width between handrails is specific to stairs adjacent to areas of rescue assistance and does not apply generally to stairs covered by 4.9.

Because handrails may interfere with egress where they adjoin seating and since accessible routes are required to connect to wheelchair seating locations, compliance with 4.9, including requirements for handrails, is not required at sides of stairs adjacent to seating in assembly areas.

Treads must be at least 11 inches wide and uniform. Uniformity is important not only between steps but along each step; curved stairs, where the width of each tread varies, do not meet this requirement. Variation in riser height along a set of stairs can be a tripping hazard. ADAAG requires the height to be uniform but does not specify a minimum or maximum height which is addressed by most local building codes. (The CABO/ANSI A117.1-1992 standard requires a riser height between 4 to 7 inches.)

People without full use of a leg may drag a foot when ascending stairs. A smooth transition from tread to tread is essential. Open risers and abrupt or extended nosings (i.e., projecting more than 1 � inches) can catch the toe. Angled or rounded nosings or sloped risers help prevent this hazard and provide a smoother transition. Straight risers without nosings are acceptable. ADAAG specifies the radius of the curvature of the leading edge of treads and the underside slope of angled or rounded nosings.

Continuous handrails are required along both sides of stairs. A center rail is not specified for wide stairways by ADAAG but may be required by local building or life safety codes.

Use of a handrail requires the formation of a power grip so that hands and fingers can be opposed and the surface of the palm can be in maximum contact with the rail surface. Large sections, particularly those of rectangular design, are not as graspable as smaller circular sections. A gripping surface width between 1� to 1� inches diameter is specified. Also permitted are rails that allow an opposing grip similar to that possible with a circular section of 1� to 1� inch diameter. Standard IPS pipe designated as 1� to 1� inch is acceptable. (Consider a 1� inch specification for pipe since a 1� inch specification may result in an outer diameter close to 2 inches.) The 1� inch clearance between walls and handrails is an absolute dimension; it provides knuckle clearance while preventing entrapment of the arm for people who lean on rails with their forearm.

Extensions at the top provide support before the first step is made. The bottom extension is especially important in providing this support until one is fully vertical. For extensions to provide this support, they must be in line with the direction of travel on the stairs. Extensions are not required in alterations if they project into cross circulation paths. Extensions must be rounded or returned to the walls, floors, or posts. Requirements for protruding objects in 4.4 limit post-mounted overhangs to 12 inches if the leading edge is higher than 27 inches from the floor.

A requirement for detectable warnings has not been specified because of lack of data regarding effectiveness.

Elevators are required in "multi-story" facilities. There may be more than one floor level, such as a mezzanine, within a "story" but the requirement for an elevator applies to buildings with more than one story. While mezzanines and levels within a story are not counted in determining whether an elevator is required, elevators must serve mezzanines where one is required or provided anyway. Under ADAAG, a floor must contain occupiable space in order to be considered a "story." ADAAG defines "occupiable" in part as "a room or enclosed space designed for human occupancy ... which is equipped with means of egress, light, and ventilation." Thus, if a building has two floors and only one provides any occupiable space, there is no requirement for an elevator.

While elevators are the primary means of vertical access between floors, an exception is allowed for buildings that have less than three stories or less than 3,000 square feet per floor. Either condition satisfies this exception. Vertical access by other means (ramp or lift) is not required to upper stories in exempt facilities. This exception is not allowed for:

The Department of Justice (DOJ) title III regulation and technical assistance manual provide important information on this exception, including definitions of these facilities. The DOJ regulation for title II does not permit an exception for state and local government facilities.

Floors above or below the accessible floor in buildings without elevators must still fully comply with ADAAG. This is required for several reasons: some people with mobility impairments can use stairs, ADAAG addresses access for people with hearing or vision impairments as well as mobility impairments, and elevator access may be provided in future alterations or additions. Also, if toilet or bathing facilities are provided on an inaccessible level in a building that qualifies for the elevator exception, then toilet or bathing facilities must be provided on the accessible level as well.

In alterations, ADAAG does not require a level of access greater than that required in new construction. Thus, the exception from the requirement for an elevator in buildings with less than 3 stories or with less than 3,000 square feet per floor applies to altered facilities as well, including those where an area containing a "primary function" is altered. For those not exempt, ADAAG provides guidance on the type of alterations that may require vertical access between floors: major structural modifications resulting from replacement or addition of stairs or escalators. This guidance is key in determining whether an elevator is required in buildings where an alteration increases the number of stories or square footage per floor above the number recognized by the exception. In a building not exempt from the elevator requirement, vertical access may be required as part of the path of travel to altered primary function areas when the cost is not "disproportionate."

The intended scope of work and technical feasibility are key factors in determining compliance in alterations to existing elevators. For example, if the planned scope of work is limited to replacement of an elevator cab’s control panel, then at a minimum the new control panel must comply to the maximum extent feasible. Or, if an alteration involves replacing the cab but not the existing shaft, ADAAG recognizes that meeting the minimum car plan dimensions may not be technically feasible due to the existing shaft configuration; in this case, smaller cab sizes are permitted. Special provisions based on technical infeasiblity for car dimensions and automatic door reopening devices in 4.1.6(3)(c) are further discussed below.

Destination-oriented elevators are different from typical elevators in that they provide a means of indicating the desired floor at the location of the call button, usually through a key pad, instead of a control panel inside the car. Responding cars are programmed for maximum efficiency by reducing the number of stops any passenger experiences. ADAAG currently does not specifically address this type of elevator, which was not widely in use when ADAAG was first published. However, where provided destination-oriented elevators must meet the technical requirements in 4.10 as appropriate. For example, ADAAG requires audible and visual car position indicators which typically identify floors as they are passed; with destination-oriented elevators, audible and visual indicators must be provided indicating the car destination both when the car arrives in response to the call and when it arrives at the floor destination.

The elevator must be automatically operable by the passenger. Self-leveling must correct the overtravel or undertravel of a car as it stops at a landing within a � inch vertical tolerance since changes in level greater than � inch can be troublesome for someone using a wheelchair.

These specifications apply to all hall call buttons provided, including those that serve cars that operate independently from others in the same bank or lobby. Recommendation: Buttons that are raised from the faceplate (or trim ring or ferrule) are preferred because they can be activated by other parts of the hand, not just the finger tip. (Buttons can be flush, but not recessed).

Audible signals serve people with visual impairments by indicating which car is answering the call and its travel direction. Audible signals sound once for the up direction, twice for down. Visual signals provide this information to people who are deaf or hard of hearing. At least one visible signal must serve each car. A separate fixture for each direction is not required; two-stop elevator cars can be served by one fixture that indicates car arrival. All lanterns must be visible from the vicinity of each set of call buttons serving the elevator. Up and down lantern indicators can be placed one above the other or side-by-side. More than one lantern is not required when located inside cars so long as it is visible from the vicinity of the hall call buttons. (Note that in-car lanterns increase door opening time since timing begins after doors open wide enough for the lantern to be visible).

Raised and Braille floor designations are required on both jambs, with the centerline 60 inches from the finished floor. Raised characters must be 2 inches high. Braille characters are often located below raised characters, although the location is not specified in ADAAG. Recommendation: Since Braille characters can be difficult to read if placed too close to raised characters, consider a vertical clearance of at least d inch. Raised borders can confuse tactile reading of raised characters (and Braille) and should be avoided or spaced away from raised text.

Door reopening devices must be able to detect obstructions without contact; otherwise, they can disrupt the balance of people using crutches or canes. They must stop and reopen doors for at least 20 seconds (while obstructed); doors do not have to fully reopen and can close sooner if no longer obstructed. Door safety edges, used alone as the reopening device, are permitted only in alterations where installation of an automatic reopening device is not technically feasible.

Door and Signal Timing for Hall Calls [4.10.7], Door Delay for Car Calls [4.10.8]

Timing, based on the distance between the farthest call button and the elevator door, begins with visible and audible signaling of car arrival. The minimum time between notification and the start of door closing is 5 seconds. Doors must remain open at least 3 seconds in response to a call.

The car dimensions specified in ADAAG are based on earlier accessibility guidelines developed in accord with industry standards. Alternate dimensions that provide wheelchair turning space (60 inch diameter circle or T-turn) wholly within the car are acceptable. Hospital-type cars sized to accommodate stretchers (usually at least 80 inches long) can have side-opening doors if the car is at least 60 inches wide. The primary test is whether a wheelchair user can enter the car, maneuver within reach of the controls and exit. In alterations, smaller car sizes (minimum 47 inch width and 69 inch length) are permitted in cases of technical infeasibility, including where limited by existing shaft configurations (minimum car size is 48 by 48 inches). See ADAAG 4.1.6(3)(c).

Control panels must be located so that no floor button is higher than 54 inches for a side reach and 48 inches for a front approach. Recommendations: Buttons on front panels should be located as close to the door as possible, rather than near the corner. Alignment for a side reach is often difficult at panels on the front of cars due to the limited maneuvering space; consider a maximum height of 48 inches for panels on the front of cars. Various control panel designs that accommodate people of short stature, people who use wheelchairs, and all standing passengers are now readily available.

Visual and audible signals that indicate car position are required. Verbal announcements are acceptable and can substitute for chimes or other audible signals. Verbal announcements must announce each floor a car stops at but not each floor passed.

Emergency two-way communication devices, where provided, must meet the ASME A17.1-1990 standard. In order to accommodate people with hearing or speech impairments, ADAAG also specifies that the system not rely solely on voice communication. A voice intercommunication system is not required by ADAAG. An audio system with a visual display can provide information on the status of a rescue. Clearly labeled visual displays can be as simple as lighted jewels that indicate that the call for help has been activated and that this message has been received. Voice intercommunication or other audible systems will provide access for people with vision impairments. The highest operable portion of the communication device must be no higher than 48 inches and no lower than 15 inches. Recommendation: Devices that do not require handsets are easier to use by people who have a limited reach. Also, handset compartments with small handles are difficult to open by people who have difficulty grasping.

Emergency communication devices must be identified by a raised symbol with lettering that must be readable (i.e., complies with specifications for character proportion [4.30.2] and height [4.30.3] and contrast [4.30.5]). The specifications for non-raised characters also apply to instructions for the use of the system.

In new construction, platform lifts can be used instead of ramps or elevators only in providing access to:

Platform lifts are also permitted where ramp or elevator access is infeasible due to existing or other constraints.

Performing areas include spaces typically elevated or depressed and used primarily for purposes of entertainment, including stages, arena floors, and orchestra pits. Lifts can be used to provide access to these areas and, if located on the same level, other areas intended for use by performers but not the public, such as dressing and locker rooms.

ADAAG requires that lines of sight provided for people using wheelchair locations in assembly areas be comparable to those for the general public. Where the seating capacity exceeds 300, wheelchair locations are required to be dispersed in most cases. Platform lifts can be used to provide access to wheelchair locations in order to meet the line of sight or dispersion requirements of 4.33.3.

These can include work areas such as equipment control rooms, projection booths, radio and news booths, press boxes, and other occupiable spaces of incidental use where the maximum occupancy is five and that are not open to the general public.

Platform lifts are permitted where "existing or other constraints" make ramp or elevator access "infeasible." This is intended to cover altered facilities where limited space or other constraints preclude construction of a complying ramp. An example might include construction of a new infill building with a historic facade which must be maintained (thus predetermining the entry floor level) and where space for a ramp is not available.

Platform lifts must comply with all applicable state and local codes and with the ASME A17.1 Safety Code for Elevators and Escalators, Section XX (1990). The ASME code provides specifications for vertical wheelchair lifts and inclined wheelchair lifts. (It also covers inclined stairway chairlifts, but this type of lift, if the chair is fixed in place, does not meet ADAAG requirements for a platform that accommodates wheelchairs). Questions on the ASME standard should be directed to the American Society of Mechanical Engineers at (212) 705-8500.

Vertical lifts are intended for people who use wheelchairs although others may be able to use them under the ASME code if a seat is provided. However, if a fixed seat is provided, the minimum space required for wheelchairs must still be provided. Folding or flip-down seats can be used. The ASME code specifies a maximum travel distance of 12 feet and prohibits penetration of floors.

Inclined wheelchair lifts, which are often installed along stairways, provide a platform accommodating a person using a wheelchair or scooter. Codes generally prohibit inclined lifts from reducing the required width of egress routes. The ASME standard allows inclined lifts with enclosures and those without. Those not enclosed, which are often stowed in a folded position, must be attendant-operated under the ASME standard. ADAAG's requirement for independent operation [4.11.3] prohibits most, if not all, lifts that must be operated by an attendant.

To be part of an accessible route, lift platforms must provide the amount of clear space required for wheelchairs in ADAAG 4.2.4. The minimum dimensions are based on the approach. Where entry and exit are on the narrow dimension, the space must be at least 36 inches wide and at least 48 inches long. Where entry and exit are at a right angle to each other, the space must be at least 60 inches long so that maneuvering room for the necessary turn is provided. Platform surfaces must be firm, stable, and slip-resistant as required in 4.5. In addition, changes in level between � to � inch must be beveled with a slope 1:2 maximum; changes in level more than � inch must be treated as a ramp.

Platform lifts must be independently usable. Lifts that are required to be "attendant-operated" by the ASME code, such as inclined wheelchair lifts that are not enclosed, do not meet this requirement. All lifts addressed by Chapter XX of the ASME code are required to be key operated. Permanently fixed keys can provide the level of "unassisted" use and operation required by ADAAG. (Issuance of keys to specific individuals is acceptable for lifts serving incidental, not public, spaces used by a specific set of users, often employees). Controls must meet requirements in 4.27 for controls and operating mechanisms.