Recommendations on Standards for the Design of Medical Diagnostic Equipment for Adults with Disabilities, Advisory Committee Final Report

5.8.1 Wheelchair Spaces on Raised Platforms Recommendations

Description: Proposed section M303 provides technical criteria for diagnostic equipment used by patients seated in a wheelchair. The provisions allow patients who use wheelchairs to position their devices at equipment typically used in a standing position such as mammography equipment, and applies to equipment specifically designed for patients seated in a wheelchair such as weight scales. Portable and fold-up weight scales with wheelchair spaces are also the ubiquitous example of diagnostic equipment with raised platforms. The proposed recommendations address considerations unique to these.

NPRM Proposed Provision: M303.2 Wheelchair Spaces. A wheelchair space complying with M303.2 shall be provided at diagnostic equipment.

M303.2.2 Width. Wheelchair spaces shall be 36 inches wide minimum.

M303.2.3 Depth. Where wheelchair spaces can be entered from the front or rear, the wheelchair space shall be 48 inches deep minimum. Where wheelchair spaces can be entered only from the side, the wheelchair space shall be 60 inches deep minimum.

NPRM Preamble Discussion: The Access Board is considering adding exceptions in the final standards to the minimum width in M303.2.2 and the minimum depth in M303.2.3 for diagnostic equipment with wheelchair spaces on raised platforms.

5.8.1.1 Clear Platform Size Recommendation

The Committee recommends a platform size with a minimum clear width of 32 inches and a minimum clear length of 40 inches.

Rationale for the recommendation

The platform size of 32 inches minimum width by 40 inches minimum length accommodates both manual and power wheeled mobility devices including small and mid-size scooters. This platform size may not accommodate some larger scooters with a 4-wheel base. The Wheeled Mobility Anthropometry Project recommends this platform dimension.^iv These study findings noted that a 36-inch length accommodates standard manual and power wheelchairs and most, if not all, large size-extra wide manual chairs. This size platform allows the person to maneuver and position the device even though many devices may not stop precisely in the middle of the platform.

To have an accurate weight, the entire wheelbase (either 3 or 4 wheels) of a mobility device must rest on and make contact with the platform. The foot pedals, footrests, scooter deck and tip wheels can overhang or extend beyond the platform and still get an accurate weight.^II

The Wheeled Mobility Anthropometry Project research summarizes wheelbase measurements on wheeled mobility devices shown in the table below.4

Table 5.8.1.1
Wheelbase Measurements on Wheeled Mobility Devices

Table ![sic]: Range and percentile values for wheelbase (inches) by mobility device type

[Click image above to view HTML version]

The Wheeled Mobility Anthropometry Project recommends a minimum flat surface of 40 inches length for platforms accommodating wheeled mobility devices including scooters and a minimum flat surface of 33 inches length for platforms accommodating wheeled mobility devices excluding scooters.

Figure 5.8.1.1 Clear Platform Size
(SOURCE: U.S. Access Board)

Notes

^II The IDeA Center in its research defined wheelchair wheelbase as the distance from the center of the primary drive wheel to the center of the caster measured parallel to the floor. It defines scooter wheelbase as the distance from the center of the primary drive wheels to the center of the back or front wheels measured parallel to the floor.

Section 5 References

^iv IDeA Center Study at the University of Buffalo, New York: Summary analysis of wheelbase measurements on wheeled mobility devices.

5.8.1.2 Entry to Wheelchair Spaces on Raised Platforms
Recommendations

Description: Entry to wheelchair spaces on raised surfaces greater than ¼ inch in height requires a transition via a bevel or ramp so that people using mobility devices will be able to maneuver onto and off it. The proposed provision includes technical criteria for changes in level at the entry of a wheelchair space. This change in level may occur on wheelchair weight scales with raised platforms. The technical criteria are consistent with the 2010 Standards.

NPRM Proposed Provision: M303.3 Entry. Where there is a change in level at the entry to a wheelchair space, the change in level shall comply with M303.3.

M303.3.3 Ramped. Changes in level greater than ½ inch high shall be ramped and shall comply with M303.3.3.

M303.3.3.1 Running Slope. Ramp runs shall have a running slope no steeper than 1:12.

M303.3.3.4 Edge Protection. Ramps with drop offs ½ inch or greater shall provide edge protection 2 inches high minimum on each side.

5.8.1.2.1 Ramped Entry Slope Recommendations

The Committee recommends that raised platforms have a ramp with slopes that do not exceed the following:

• At 0 to 1½ inches, the slope is 1:2
• At greater than 1½ to 2½ inches, the slope is 1:8
• At greater than 2½ inches, the slope is 1:12

Rationale for the recommendation

The Committee considered the needs of a ramped surface to access the platform on the accessible scale. Because there are different types of scales with different platform heights, the Committee developed a three tiered ramp slope proposal to fit different situations.

The Committee reviewed and discussed the provisions on slopes for ramps as they apply to architectural elements in the built environment. The maximum slope for a ramp in the 2010 Standards is a rise of 1 vertical inch for each 12 inches of horizontal distance slope. Under very limited conditions in the built environment, the 2010 Standards allow a steeper ramp for a limited rise. A ramp in the built environment to which this exception applies may use a 1:2 grade slope on a short rise ramp.

Industry experts spoke to the concern for facility space often expressed by healthcare entities. The space constraints affect the desirability of accessible scales since space is often expensive and tight in many medical facilities. Scales that can be wall mounted or portable enhance the flexibility of scales and allow use in tight environments. Currently, these types of accessible scales use the short rise ramp to facilitate easy storage or mounting.

Existing technology for weight cell load allows a for a platform profile to go as low as ¾ to 1½ inches. As the height of the platform lowers, the length of the ramp can decrease. The trend in the scale industry is to develop lower weight cell technology. However, industry currently does not know if lower profiles are possible.

Some Committee members pointed out that these provisions create exceptions from the existing 2010 Standards.

5.8.1.2.2 Single Ramped Entry - Edge Protection on the Platform and Platform Sides Recommendations

The Committee recommends a two-inch high edge protection on the back of the platform opposite the entry ramp and a minimum two-inch high edge protection on the sides of the platform.

Rationale for the recommendation

The edge protection adds a safety feature to prevent wheeled mobility device users from “over-shooting” the platform edges and tipping, falling, etc. Not all mobility devices stop immediately when braking to stop. The limitation on edge protection height will reduce the possibility that the edge protection will interfere with the patient’s footrest.

5.8.1.2.2 Single Ramp Scale with Edge Protection
(SOURCE: U.S. Access Board)

5.8.1.2.3 Double Ramped Entry - Edge Protection on the Platform sides Recommendations

The Committee recommends a minimum two-inch high edge protection on both sides of the platform for double ramped entry platforms.

Rationale for the recommendation

Edge protection provides an additional safety feature and guides users of wheeled mobility devices on the platform. The protection stops the mobility device from driving off either side of the platform.

5.8.1.2.3 Double Ramp Scale with Edge Protection
(SOURCE: U.S. Access Board)

5.8.1.2.4 Edge Protection on Platforms 1½ inches or less in Height Recommendations

The Committee recommends that no edge protection be required on platforms of 1½ inches or less in height.

Rationale for the recommendation

Edge protection on platforms of heights of 1½ inches or less is not required because the low height profile does not pose a safety hazard to users when on the platform.