< Previousuniversal design guidelines for feature stairs 40 SECTION FOUR Synergi’s double-helix curved stairs are featured in the market atrium of Post Houston, a former post office turned cultural hub in Houston, Texas.41 synergillc.com Difficulty in detecting the edge of each stair leads to uncertainty and confusion when navigating a stairway, challenging comfort- able and safe navigation for all stair users. The tread edge or nosing makes up a stair’s edge and is a key attribute in stairway design that allows users to understand the eleva- tion changes between steps, placement of the leading foot, and to establish and control gait. Stairway Walkability42 Section 4|Stairway Walkability Slip-Resistant Material. In order to prevent accidents attributed to treads, the surface of the tread should be topped with a reasonably slip-resistant mate- rial. Ensure a consistent slip-resistant rating throughout a stair, including the tactile indicators on landings, to improve usability and reduce slips and trips. Anti-Slip Covers. For preexisting stairs with slippery treads, an anti-slip covering can be easily installed. Applying an anti-slip cover, such as an abrasive silicon carbide or sand blasted aluminum, can help prevent accidents. SLIP-RESISTANT SURFACES Stair climbing is affected by the physical properties of the tread material. Where adjacent materials have different frictional characteristics, they can present a slip or trip hazard to all building users, especially those with mobility difficulties. According to the U.S. Access Board, walking surfaces should be “stable, firm, and slip-resistant”.43 universal design guidelines for feature stairs synergillc.com | 2022 Avoid Smooth Materials. Smoother tread materials such as wood could cause users’ feet to slip out from underneath them, particularly if the stair becomes wet. Avoid Using Glass. In addition to reducing the visibility and detect- ability of tread edges, glass decreases the friction between shoes and treads, increasing the likelihood of the user to misstep. Of common flooring materials, glass tends to perform less well in wet conditions since water reduces friction between shoes and treads. Although non-slip treatments are available for glass used as a walking surface, these treatments may not be adequate because water is not absorbed by glass. Where users are likely to track water in from the outdoors, water on treads may actually negate the effect of “non-slip” coatings and textures.44 Section 4|Stairway Walkability VISUAL STAIR INDICATORS For stair users with low vision, locating the first and last stairs are often the most challenging tasks of stair navigation. Unless each stair’s edge is clearly marked or each step casts sufficient shadows on the risers, PLV may require a cane or use their feet to feel for the edge of a stair. By knowing where the first stair is, PLV build a mental model about the stair dimensions and extrapolate this knowledge to the rest of the stairs. Thus, the detection of stair edges is especially important to their safely and confidently navigating stairs. The use of visual highlights or indicators, such as contrast stripes, serve as cues to demarcate stairways, enabling stair users to easily detect the exact posi- tion of surface level changes even from a distance. Contrast Stripes. Contrasting mate- rials on the step edge/nosing and handrail can provide a very effective visual safety trigger. Contrast stripes on the nosing of a staircase help outline each stair, which is especially helpful when descending stairs. High contrast edges can provide a very effective visual safety trigger – not only do they provide better cues in both the central and periph- eral zones of vision, but they also prevent steps from appearing to blend together to create a dangerous illusion of a ramp. Without indicators, the edges of these stairs are hard to detect. contrast stripes to facilitate the detection of stair edges45 universal design guidelines for feature stairs synergillc.com | 2022 color contrast visual cues Color Contrast. The contrast of a stair’s edge or nosing is vital for its detection and usefulness. Contrast is about lightness or darkness, not color. Colors that look different may, in fact, have little contrast. A black and white image can provide a useful indication of the visual contrast. Stripe Contrast. Contrast stripes or nosings should have high color and luminance contrast. Nosing stripes should provide at least 30% luminance contrast to the tread. Single Stripe Color. Where colored nosings are used to indicate a stair edge, nosings should be a single color. Two parallel stripes of different colors can give a false impression of the location of the step edge, and these nosings should be avoided. While these stairs do utilize high-con- trast stripes that are sufficiently wide, the stripes are discontinuous and do not run the full width of each stair.46 Section 4|Stairway Walkability Stripe Placement. Stripes should be placed directly on the edge of the stair and should extend the full width of the step. Stripes placed away from the edge mislead those who rely upon their use. Differentiate Landings. Some stairs have an extra contrast stripe on the landing. Some PLV rely on monocular cues, such as color changes, to deduce depth changes. By using contrast stripes to mark each step, such stair users come to associate each stripe with a step when navigating stairs, including this extra stripe. This last contrast stripe on the landing can thus cause tripping. These stairs in London’s underground subway station use high-contrast stripes to indicate the last step before a landing is reached. These stair edges are made difficult to detect due to the use of multiple stripes, misplacement (too far from the stair edge), and do not run continuously from one side to the other. 47 universal design guidelines for feature stairs synergillc.com | 2022 Luminance Contrast. For those with difficulty distin- guishing colors, luminance contrast – which generates a difference in brightness – can be more effective than color contrast. Reflective metal and illuminated strips, such as the kind commonly used in movie theaters, use luminance to create brightness contrast. With luminance, shadow and reflection cues are used to perceive depth changes. It is recommended that nosing strips provide at least 30% luminance contrast to the stair tread and a depth of between 50 to 75 millimeters. Light Indicators. The use of lighting as a visual indicator should be thought- fully considered; if too bright, it may prevent users from seeing other critical stair elements. Light should be pointed downwards, not shining directly into a user’s line of sight. Avoid stair lighting that is too bright (above) or pointed upwards, as is of- ten used in movie theaters (below). luminance contrast visual cues48 Section 4|Stairway Walkability Reflective Indicators. Reflective contrast stripes (pictured right), such as those made from thin metal strips, may only be visible when they catch bright light, which needs to be consistently provided. Shadow Indicators. Shadows, which have high luminance contrast, are often an effective visual cue. Seeing the shadows on the risers and treads of the stairs can help identify stairs. However, sometimes shadows cause the illu- sions of stairs, which can cause confusion for PLV and other stair users (pictured above).49 universal design guidelines for feature stairs synergillc.com | 2022 To better help stair users identify the start and end of a stairway, the use of a tactile hazard warn- ing surface at the top and bottom of a flight of inter- nal stairs and/or along stair edges may provide a means of highlighting the approaching change in level. TACTILE INDICATORS Non-Slip Materials. Tactile hazard warning surfaces are typically manufactured from relatively hard, non-slip materials such as durable GRP (glass reinforced polyester). They have different frictional characteristics from floor finishes commonly found in internal environments, such as vinyl flooring, linoleum, and carpet and improve grip. Tactile/Anti-Slip Nosing. Nosing can be covered in an anti-slip material to further protect users. In fact, many states, including New York and California, require all commercial stairs to feature an anti-slip material along the nosing. Stairs without an existing anti-slip nosing can be easily retrofitted with one. Slip-resistant strips should be 40 mm wide at minimum and should not extend more than 1 mm above the tread surface.Next >