The Americans Disabilities Act (ADA)
recommends the static COF of 0.6 on flat surfaces both wet and dry,
and 0.8 for ramps.
Concrete wheelchair ramps have the best slip resistance. There are several ways to make concrete surface rough without adding cost. Sweeping the green surface with a broom is the easiest.
Wooden wheelchair ramps use mill finished lumber that is usually very smooth and not very slip-resistant. However, the flexibility of wood compensates its drawback. When a board is loaded, it sinks slightly, which makes the surface uneven, which in turn makes it slip-resistant. In very wet conditions, wooden ramps need additional surface treatment such as coating or non-slip tape to increase its roughness.
In the case of portable wheelchair ramps, things are a little more complicated. Aluminum is the material used by 99% of all portable handicap ramps. But extruded aluminum panels are extremely smooth and slippery. It is impossible to roughen up the surface during extrusion.
There are 3 options to make aluminum slip-resistant.
1. Make the surface perforated.
Perforation is the process to punch small holes on the ramps surface. Ideally, these holes should be punched from the bottom up so that the edges rise about the surface. Perforated surface has excellent slip resistance. Perforation also helps water drainage. If done correctly, this type of surface can meet ADA standards. But there are two major drawbacks for this method – 1. perforation weakens the ramp surface; and 2. high manufacturing costs. Perforation is rarely used these days.
2. Anti-slip groove in aluminum
Forming grooves on extruded aluminum does not increase manufacturing cost because it is done during extrusion without additional processes. Groove do not affect mechanical strength neither. Almost all low-end, cheap wheelchair ramps employe this method.
In our opinion, grooved aluminum surface will NEVER meet ADA standard due to 2 reasons:
First, grooves have decent COF perpendicularly but very poor COF parallelly. When movement is parallel to the grooves, the difference between a grooved surface and a smooth is none. When a person walks on a ramp, or a wheelchair is rolled on a ramp, the contact movement is typically a combination of both perpendicular and parallel motions. A good slip-resistant surface needs to be non-directional, or slippage would start in the direction of least resistance.
Secondly, grooves have poor drainage. Water runoff won’t occur until the grooves are completely filled with water. This means even the slightest accumulation of moisture, such as that from morning dews, can turn grooves into rivers and ramps into slip hazards.
We do not use grooved surface and would recommend any serious customer to stay away from this flawed but cheap design.
3. Non-skip or non-slip tape
Non-slip tape is made of tough vinyl material coated with adhesive on one side and silicon carbide on the other side. The adhesive has paper backing. When a ramp is finished, the paper backing is peeled off and the the tape was pressed onto the ramp surface. Walking on non-slip tape is literally walking on sand paper. The vinyl base also makes the ramp somewhat pliable, further enhancing friction characteristics. COF is uniform in all directions. Water drainage is a non issue – vinyl is water repellent and water runoff is fast.
Non-slip tape is a safety product. Therefore, it is subject to government regulation, such as the USA Occupational Safety & Health Administration (OSHA). It is tested in both dry and wet conditions. The non-slip tape we use easily meets ADA standards under both dry and wet conditions.
The only drawback of non-slip tape is additional cost. For these reason, only premium wheelchair ramps use non-slip tape.
To ensure personal safety, our use non-slip tape on all our ramps.