Chapter R4: Supplementary Technical Requirements

R401 General

R401.1 Scope. The supplemental technical requirements in Chapter 4 shall apply where required by Chapter 2 or where referenced by a requirement in this document.


R402 Protruding Objects


R402.1 General. Protruding objects shall comply with R402.

R402.2 Protrusion Limits. Objects with leading edges more than 685 mm (2.25 ft) and not more than 2 m (6.7 ft) above the finish surface shall protrude 100 mm (4 in) maximum horizontally into pedestrian circulation paths.

Figure R402.2 Protrusion Limits

A frontal view shows a person using a cane walking along a wall.  A wall-mounted object more than 685 mm (27 in) from the floor protrudes no more than 100 mm (4 in) from the wall surface.  An object overhead provides vertical clearance that is greater than 2 m (80 in).


R402.3 Post-Mounted Objects. Where objects are mounted on free-standing posts or pylons and the objects are 685 mm (2.25 ft) minimum and 2030 mm (6.7 ft) maximum above the finish surface, the objects shall overhang pedestrian circulation paths 100 mm (4 in) maximum measured horizontally from the post or pylon base. The base dimension shall be 64 mm (2.5 in) thick minimum. Where objects are mounted between posts or pylons and the clear distance between the posts or pylons is greater than 305 mm (1.0 ft), the lowest edge of the object shall be 685 mm (2.25 ft) maximum or 2 m (6.7 ft) minimum above the finish surface.

Figure R402.3 Post-Mounted Objects

Objects mounted on posts/ pylons 685 mm – 2 m (27 – 80 in) above the finish surface with overhangs limited to 100 mm (4 in) max measured from the post/ pylon base.  Object mounted between posts or pylons separated more than 305 mm (12 in) with its lowest edge 685 mm (27 in) max or 2 m (80 in) min above the finish surface.

R402.4 Reduced Vertical Clearance. Guardrails or other barriers to pedestrian travel shall be provided where the vertical clearance is less than 2 m (6.7 ft) high. The leading edge of the guardrail or barrier shall be located 685 mm (2.25 ft) maximum above the finish surface.

Figure R402.4 Reduced Vertical Clearance

Guardrail/barrier with leading edge 685 mm (27 in) above the finish surface located where vertical clearance is less than 2 m (80 in) above the finish surface


R403 Operable Parts

R403.1 General. Operable parts shall comply with R403.

Advisory R403.1 General. Operable parts on accessible pedestrian signals and pedestrian pushbuttons (see R209) and parking meters and parking pay stations that serve accessible parking spaces (see R309.5) must comply with R403.

R403.2 Clear Space. A clear space complying with R404 shall be provided at operable parts.

R403.3 Height. Operable parts shall be placed within one or more of the reach ranges specified in R406.

R403.4 Operation. Operable parts shall be operable with one hand and shall not require tight grasping, pinching, or twisting of the wrist. The force required to activate operable parts shall be 22 N (5 lbs) maximum.


R404 Clear Spaces

R404.1 General.
Clear spaces shall comply with R404.

Advisory R404.1 General. Clear spaces are required at operable parts (see R403.2), including accessible pedestrian signals and pedestrian pushbuttons (see R209) and parking meters and parking pay stations that serve accessible parking spaces (see R309.5). Clear spaces are also required at benches (see R212.6) and within transit shelters (see R308.2).

R404.2 Surfaces. Surfaces of clear spaces shall comply with R302.7 and shall have a running slope consistent with the grade of the adjacent pedestrian access route and cross slope of 2 percent maximum.

R404.3 Size. Clear spaces shall be 760 mm (2.5 ft) minimum by 1220 mm (4.0 ft) minimum.

R404.4 Knee and Toe Clearance. Unless otherwise specified, clear spaces shall be permitted to include knee and toe clearance complying with R405.

R404.5.Position. Unless otherwise specified, clear spaces shall be positioned for either forward or parallel approach to an element.

R404.6 Approach. One full unobstructed side of a clear space shall adjoin a pedestrian access route or adjoin another clear space.

R404.7 Maneuvering Space. Where a clear space is confined on all or part of three sides, additional maneuvering space shall be provided in accordance with R404.7.1 and R404.7.2.

R404.7.1 Forward Approach. The clear space and additional maneuvering space shall be 915 mm (3.0 ft) wide minimum where the depth exceeds 610 mm (2.0 ft).

R404.7.2 Parallel Approach. The clear space and additional maneuvering space shall be 1525 mm (5.0 ft) wide minimum where the depth exceeds 380 mm (1.25 ft).


R405 Knee and Toe Clearance

R405.1 General. Where space beneath an element is included as part of a clear space, the space shall comply with R405. Additional space shall not be prohibited beneath an element but shall not be considered as part of the clear space.

Advisory R405.1 General. Clearances are measured in relation to the usable clear space, not necessarily to the vertical support for an element. When determining clearance under an object, care should be taken to ensure that the space is clear of any obstructions.

R405.2 Toe Clearance

R405.2.1 General. Space under an element between the finish surface and 230 mm (9 in) above the finish surface shall be considered toe clearance and shall comply with R405.2.

R405.2.2 Maximum Depth. Toe clearance shall extend 635 mm (2.1 ft) maximum under an element.

R405.2.3 Minimum Required Depth. Where toe clearance is required at an element as part of a clear space, the toe clearance shall extend 430 mm (1.4 ft) minimum under the element.

R405.2.4 Width. Toe clearance shall be 760 mm (2.5 ft) wide minimum.

Figure R405.2 Toe Clearance

Toe clearance (elevation) is 230 mm (9 in) high min and 150 mm (6 in) deep max.  Toe clearance (plan) is 760 mm (30 in) wide min, and object overlaps 430 – 635 mm (17 - 25 in) of the length.


R405.3 Knee Clearance

R405.3.1 General. Space under an element between 230 mm (9 in) and 685 mm (2.25 ft) above the finish surface shall be considered knee clearance and shall comply with R405.3.

R405.3.2 Maximum Depth. Knee clearance shall extend 635 mm (2.1 ft) maximum under an element at 230 mm (9 in) above the finish surface.

R405.3.3 Minimum Required Depth. Where knee clearance is required under an element as part of a clear space, the knee clearance shall be 280 mm (11 in) deep minimum at 230 mm (9 in) above the finish surface, and 205 mm (8 in) deep minimum at 685 mm (2.25 ft) above the finish surface.

R405.3.4 Clearance Reduction. Between 230 mm (9 in) and 685 mm (2.25 ft) above the finish surface, the knee clearance shall be permitted to reduce at a rate of 25 mm (1 in) in depth for each 150 mm (6 in) in height.

R405.3.5 Width. Knee clearance shall be 760 mm (2.5 ft) wide minimum.

Figure R405.3 Knee Clearance

Knee clearance (elevation) is 685 mm (27) high min for a depth of 205 mm (8 in) min that slopes down to 230 mm (in) min at a depth of 280 mm (11 in) min.   Knee clearance (plan) is 760 mm (30 in) wide min and with object overlapping it by 635 mm (25 in) max.


R406 Reach Ranges

R406.1 General. Reach ranges shall comply with R406.

R406.2 Unobstructed Forward Reach. Where a forward reach is unobstructed, the high forward reach shall be 1220 mm (4.0 ft) maximum and the low forward reach shall be 380 mm (1.25 ft) minimum above the finish surface. Forward reach over an obstruction is not permitted.

Figure R406.2 Unobstructed Forward Reach

Unobstructed forward reach shown in elevation to be 1220 mm (48 in) max to 380 mm (15 in) min above the finish surface.


R406.3 Unobstructed Side Reach. Where a clear space allows a parallel approach to an element and the side reach is unobstructed, the high side reach shall be 1220 mm (4.0 ft) maximum and the low side reach shall be 380 mm (1.25 ft) minimum above the finish surface. An obstruction shall be permitted between the clear space and the element where the depth of the obstruction is 255 mm (10 in) maximum.

Figure R406.3 Unobstructed Side Reach

Unobstructed side reach shown in elevation to be 1220 mm (48 in) max to 380 mm (15 in) min above the finish surface.


R407 Ramps

R407.1 General. Ramps shall comply with R407.

R407.2 Running Slope. Ramp runs shall have a running slope between 5 percent minimum and 8.3 percent maximum.

Advisory R407.2 Running Slope. Ramps with the least possible running slope accommodate the widest range of users. Providing stairways along with ramps, where possible, benefits pedestrians with heart disease, limited stamina, and others for whom distance presents a greater barrier than steps.

R407.3 Cross Slope. The cross slope of ramp runs shall be 2 percent maximum.

R407.4 Width. The clear width of a ramp run and, where handrails are provided, the clear width between handrails shall be 915 mm (3.0 ft) minimum.

R407.5 Rise. The rise for any ramp run shall be 760 mm (2.5 ft) maximum.

R407.6 Landings. Ramps shall have landings at the top and the bottom of each ramp run. Landings shall comply with R407.6.

Figure R407.6 Landings

Straight ramp landings 1.5 m (5 ft) min and at least as wide as ramp run and landings at ramp that changes direction 1.5 m (5 ft) min by 1.5 m (5 ft) min

R407.6.1 Slope. Landing slopes shall be 2 percent maximum in any direction.

R407.6.2 Width. The landing clear width shall be at least as wide as the widest ramp run leading to the landing.

R407.6.3 Length. The landing clear length shall be 1.5 m (5.0 ft) long minimum.

R407.6.4 Change in Direction. Ramps that change direction between runs at landings shall have a clear landing 1.5 m (5.0 ft) minimum by 1.5 m (5.0 ft) minimum.

R407.7 Surfaces. Surfaces of ramp runs and landings shall comply with R302.7.

R407.8 Handrails. Ramp runs with a rise greater than 150 mm (6 in) shall have handrails complying with R409.

R407.9 Edge Protection. Edge protection complying with R407.9.1 or R407.9.2 shall be provided on each side of ramp runs and ramp landings.

R407.9.1 Extended Ramp Surface. The surface of the ramp run or landing shall extend 305 mm (1.0 ft) minimum beyond the inside face of a handrail complying with R409.

Figure R407.9.1 Extended Ramp Surface

Surface of ramp run/ landing extending 305 mm (12 in) min beyond the inside face of handrail

Advisory R407.9.1 Extended Ramp Surface. The extended surface prevents wheelchair casters and crutch tips from slipping off the ramp surface.

R407.9.2 Curb or Barrier. A curb or barrier shall be provided that prevents the passage of a 100 mm (4 in) diameter sphere, where any portion of the sphere is within 100 mm (4 in) of the finish surface.


R408 Stairways

R408.1 General. Stairways shall comply with R408.

R408.2 Treads and Risers. All steps on a flight of stairs shall have uniform riser heights and uniform tread depths. Risers shall be 100 mm (4 in) high minimum and 180 mm (7 in) high maximum. Treads shall be 280 mm (11 in) deep minimum.

R408.3 Open Risers.
Open risers are not permitted.

R408.4 Tread Surface. Stairway treads shall comply with R302.7. Changes in level are not permitted.

R408.5 Nosings. The radius of curvature at the leading edge of the tread shall be 13 mm (0.5 inch) maximum. Nosings that project beyond risers shall have the underside of the leading edge curved or beveled. Risers shall be permitted to slope under the tread at an angle of 30 degrees maximum from vertical. The permitted projection of the nosing shall extend 38 mm (1.5 in) maximum over the tread below.

R408.6 Handrails. Stairways shall have handrails complying with R409.


R409 Handrails

R409.1 General. Handrails required at ramps and stairways, and handrails provided on pedestrian circulation paths shall comply with R409.

Advisory R409.1 General. Handrails are required on ramp runs with a rise greater than 150 mm (6 in) (see R407.8) and stairways (see R408.6). Handrails are not required on pedestrian circulation paths. However, if handrails are provided on pedestrian circulation paths, the handrails must comply with R409 (see R217). The requirements in R409.2, R409.3, and R409.10 apply only to handrails at ramps and stairways, and do not apply to handrails provided on pedestrian circulation paths.

R409.2 Where Required. Handrails shall be provided on both sides of ramps and stairways.

R409.3 Continuity. Handrails shall be continuous within the full length of each ramp run or stair flight. Inside handrails on switchback or dogleg ramps and stairways shall be continuous between ramp runs or stair flights.

R409.4 Height. Top of gripping surfaces of handrails shall be 865 mm (2.8 ft) minimum and 965 mm (3.2 ft) maximum vertically above walking surfaces, ramp surfaces, and stair nosings. Handrails shall be at a consistent height above walking surfaces, ramp surfaces, and stair nosings.

Figure R409.4 Height

Height of handrail gripping surface 865 – 965 mm (34 – 38 in) at stairs, ramps, and walking surfaces

R409.5 Clearance. Clearance between handrail gripping surfaces and adjacent surfaces shall be 38 mm (1.5 in) minimum.

R409.6 Gripping Surface. Handrail gripping surfaces shall be continuous along their length and shall not be obstructed along their tops or sides. The bottoms of handrail gripping surfaces shall not be obstructed for more than 20 percent of their length. Where provided, horizontal projections shall occur 38 mm (1.5 in) minimum below the bottom of the handrail gripping surface.

Advisory R409.6 Gripping Surface. Pedestrians with disabilities and others benefit from continuous gripping surfaces that permit users to reach the fingers outward or downward to grasp the handrail.

R409.7 Cross Section. Handrail gripping surfaces shall have a cross section complying with R409.7.1 or R409.7.2. Where expansion joints are necessary for large spans of handrails, the expansion joint is permitted to be smaller than the specified cross section diameters for a 25mm (1 in) length.

R409.7.1 Circular Cross Section. Handrail gripping surfaces with a circular cross section shall have an outside diameter of 32 mm (1.25 in) minimum and 51 mm (2 in) maximum.

R409.7.2 Non-Circular Cross Sections. Handrail gripping surfaces with a non-circular cross section shall have a perimeter dimension of 100 mm (4 in) minimum and 160 mm (6.25 in) maximum, and a cross-section dimension of 57 mm (2.25 in) maximum.

Figure R409.7.2 Non-Circular Cross Sections

Non-circular cross sections with a perimeter dimension 100 – 160 mm ( 4 – 6.25 in) and a max cross-section dimension of 57 mm (2.25 in)


R409.8 Surfaces. Handrail gripping surfaces and any surfaces adjacent to them shall be free of sharp or abrasive elements and shall have rounded edges.

R409.9 Fittings. Handrails shall not rotate within their fittings. Where expansion joints are necessary for large spans of handrails, the expansion joint is permitted to rotate in its fitting.

R409.10 Handrail Extensions. Handrail gripping surfaces shall extend beyond and in the same direction of ramp runs and stair flights in accordance with R409.10. Extensions shall not be required for continuous handrails at the inside turn of switchback or dogleg ramps and stairways. In alterations where handrail extensions would reduce the clear width required for pedestrian access routes, handrail extensions shall not be required.

R409.10.1 Top and Bottom Extension at Ramps. Ramp handrails shall extend horizontally above the landing for 305 mm (1.0 ft) minimum beyond the top and bottom of ramp runs. Extensions shall return to a wall, guard, or the landing surface, or shall be continuous to the handrail of an adjacent ramp run.

Figure R409.10.1 Top and Bottom Extension at Ramps

Handrail extensions 305 mm (12 in) min long at top and bottom of ramp

R409.10.2 Top Extension at Stairways. At the top of a stair flight, handrails shall extend horizontally above the landing for 305 mm (1.0 ft) minimum beginning directly above the first riser nosing. Extensions shall return to a wall, guard, or the landing surface, or shall be continuous to the handrail of an adjacent stair flight.

Figure R409.10.2 Top Extension at Stairways

Handrail extension 305 mm (12 in) long min at top of stair

R409.10.3 Bottom Extension at Stairways. At the bottom of a stair flight, handrails shall extend at the slope of the stair flight for a horizontal distance at least equal to one tread depth beyond the last riser nosing. Extensions shall return to a wall, guard, or the landing surface, or shall be continuous to the handrail of an adjacent stair flight.

Figure R409.10.3 Bottom Extension at Stairways

Bottom stairway handrail extending at slope of stair flight for a distance at least equal to one tread depth beyond the last riser nosing


R410 Visual Characters on Signs

R410.1 General.
Visual characters on signs shall comply with R410.

R410.2 Finish and Contrast. Characters and their background shall have a non-glare finish. Characters shall contrast with their background with either light characters on a dark background or dark characters on a light background.

Advisory R410.2.1 Finish and Contrast. Signs are more legible for pedestrians with low vision when characters contrast as much as possible with their background. Additional factors affecting the ease with which the text can be distinguished from its background include shadows cast by lighting sources, surface glare, and the uniformity of the text and its background colors and textures.

R410.3 Case. Characters shall be uppercase or lowercase or a combination of both.

R410.4 Style. Characters shall be conventional in form. Characters shall not be italic, oblique, script, highly decorative, or of other unusual forms.

R410.5 Character Proportions. Characters shall be selected from fonts where the width of the uppercase letter "O" is 55 percent minimum and 110 percent maximum of the height of the uppercase letter "I".

R410.6 Character Height. Minimum character height shall comply with Table R410.2.5. Viewing distance shall be measured as the horizontal distance between the character and an obstruction preventing further approach towards the sign. Character height shall be based on the uppercase letter "I".

R410.6 Visual Character Height

Height to Finish Surface From Baseline of Character

Horizontal Viewing Distance

Minimum Character Height

1.0 m (3.3 ft) to less than or equal to 1.8 m (5.8 ft)

Less than 1.8 m (6.0 ft)

16 mm (0.625 in)

1.8 m (6.0 ft) and greater

16 mm (0.625 in), plus 3.2 mm (0.125 in) per 0.3 m (1.0 ft) of viewing distance above 1.8 m (6.0 ft)

Greater than 1.8 m (5.8 ft) to less than or equal to 3.0 m (10.0 ft)

Less than 4.6 m (15.0 ft)

51 mm (2 in)

4.6 m (15.0 ft) and greater

51 mm (2 in), plus 3.2 mm (0.125 in) per 0.3 m (1.0 ft) of viewing distance above 4.6 m (15.0 ft)

Greater than 3.0 m (10.0 ft)

Less than 6.4 m (21.0 ft)

75 mm (3 in)

6.4 m (21.0 ft) and greater

75 mm (3 in), plus 3.2 mm (0.125 in) per 0.3 m (1.0 ft) of viewing distance above 6.4 m (21.0 ft)

R410.7 Height from Finish Surface. Visual characters shall be 1.0 m (3.25 ft) minimum above the finish surface.

R410.8 Stroke Thickness. Stroke thickness of the uppercase letter "I" shall be 10 percent minimum and 30 percent maximum of the height of the character.

R410.9 Character Spacing. Character spacing shall be measured between the two closest points of adjacent characters, excluding word spaces. Spacing between individual characters shall be 10 percent minimum and 35 percent maximum of character height.

R410.10 Line Spacing. Spacing between the baselines of separate lines of characters within a message shall be 135 percent minimum and 170 percent maximum of the character height.

R411 International Symbol of Accessibility. The International Symbol of Accessibility shall comply with Figure R411. The symbol and its background shall have a non-glare finish. The symbol shall contrast with its background with either a light symbol on a dark background or a dark symbol on a light background.

Figure R411International Symbol of Accessibility

International Symbol of Accessibility