Wheelchair ramp slope is defined as relationship of the ramp rise to length of the slope horizontal projection. Ramp slope can be described as ratio or expressed as a percentage. If it is necessary to build a wheelchair ramp near the step 10 cm high, 1 meter should be measured off from it and then using concrete this difference should be leveled in the form of the sloping surface. The wheelchair ramp with 1:10 slope or 10% will be made (Figure 1).
Calculation of the wheelchair ramp slope plays a crucial part in the ramp design. If the wheelchair ramp slope is too steep, the ramp will pose a great danger to move along and it will be difficult for a handicapped person to use it. If the wheelchair ramp slope is too gradually inclined, the ramp built by us will be longer than it is necessary and thus moving along it will be hard and take more time.
Let us consider basic principles that should be kept in mind when choosing the wheelchair ramp slope:
The wheelchair ramp slope must be no steeper than 1:12. It means length of the wheelchair ramp slope should be 1 foot at least for each inch of the slope rise.
If the building has geometric constraints, the wheelchair ramp slope can be steeper than 1:12. The wheelchair ramp slope with 1:10 ratio is considered to be suitable to rise up to 6 inches, while the slope with 1:8 ratio is acceptable for maximum rise of 3 inches.
Wheelchair ramp slope mustn't be steeper than 1:8. You shouldn't build the ramp in that place.
In places featuring humidity and icing it is advisable to build wheelchair ramps with 1:16 ratio. It will help to prevent slip of wheels.
In my opinion 5% surface slope can be called not a ramp, but a simple terrain variation, leveling of a surface or a gradual descent, because in case of such slope a disabled person will not need someone's help.
If the slope is more than 5%, it causes some difficulties for a wheel-chaired person. That is why it is necessary to mount handrails on each side or the disabled person will need someone's help.
|Slope *||Maximum Rise|
|Steeper than 1:10 but not steeper than 1:8||3 inches (75 mm)|
|Steeper than 1:12 but not steeper than 1:10||6 inches (150 mm)|
|* A slope steeper than 1:8 is prohibited.|