A ramp is a sloped pathway used to provide access between two vertical levels. It facilitates the movement of wheelchairs, bicycles, and other wheeled vehicles.
Ramps are constructed when a number of people or vehicles have to be moved from one level to another. They are widely used in public buildings, railroad stations, stadiums, hospitals, and exhibition halls.
Ramps are highly desirable for all buildings, especially to accommodate persons in wheelchairs.
The construction specifications and dimensions of a ramp depend on the standards of the respective region. This article explains some general design considerations to be followed while designing a ramp.
Determination of Slope of a Ramp
The slope of a ramp is calculated as the ratio of the height to overcome (h) to the length of the horizontal plane (d), as shown in Figure-1 below. The slope of the ramp is also called as gradient or steepness of the ramp and can be expressed either in ratio or in percentage.
Slope in percentage = (h/d) x 100
For example, if the horizontal distance 'd' = 10 m and the height of ramp h = 1 m, then the slope of the ramp is 10%.
Design of an Outdoor Ramp
The maximum slope provided to an outdoor ramp is dependent on the height to overcome (h) and the horizontal length (d) of the plane. Generally, for outdoor ramps of very small heights, a slope between 10 to 12.5% is desirable. This reduces to 8% for heights up to 50 cm, 6% for height up to 100 cm, and 5% for heights up to 150 cm. A slope of 4% is applied for ramps used by elder citizens.
When the length of the ramp is less than 1.5 m, the slope provided must be less than 12%. This slope reduces to 10% for length of ramp less than 3 m, and 8% for length less than 9 m. Always take the height of the ramp into consideration while fixing the final slope.
Example: Design a ramp to overcome a height of 55 cm.
Given Data: Height of ramp, h = 55cm
Take, Slope = 6%;
Slope of the ramp (%) = (h/d )x100
6 = (.55/d) x 100
d = 9.12m
Hence, the horizontal plane for this ramp is 9.12m.
Design of Interior Ramps
For interior ramps, a 10% slope is allowed to overcome small heights up to 30 cm. For 75 cm height, the slope reduces to 8%, and for 150cm height, the slope reduces to 6%. The slope reduces to 5% for elderly citizens.
The length of the interior ramp up to 3 m uses a slope less than 10%. For distances between 3 m and 6 m, the slope taken is less than 8%. The slope must be less than 6% when the distance is between 6 m and 9 m.
Image Courtesy: Chambersmcmillan Architects
Shape of Ramps
The important design considerations for the shape of ramps are as follows:
- The length of ramps is made straight in most cases. Curved ramps make the movement of wheelchair difficult.
- The transverse slope of the ramp must not be greater than 2%. This helps to avoid lateral slippage.
- For every change in the ramp's direction, a horizontal landing of a minimum 50 cm diameter is provided. This diameter helps for 360-degree rotation of the wheelchair.
Width of the Ramp
Generally, a clearance space of 120 to 180 cm between the handrails is recommended to allow comfortable and easy passage of the wheelchair through the ramp. For ramps designed for width greater than 180 cm, an intermediate handrail can be provided. Always consider the maneuvering space of the person with a wheelchair or the person with a baby carriage while determining the width of the ramp.
Materials Used for Ramp Construction
The ramp can be constructed either out of concrete or steel. Whatever be the base material, the finishing material of the ramp must provide a hard non-slip surface. This surface must work safely both in dry and wet conditions.
For better safety, provide a tactile pavement at the start and end of the ramp’s horizontal plane. This is provided in different colors to serve as a warning for people with low vision. This must be applied to highlight the perimeter of the ramps.
Handrails for Ramps
The design considerations for handrails for ramps are as follows:
- Handrails for ramps are continuously provided without any interruption along the length on either side.
- Handrails are built in a fixed position.
- The handrails are made out of smooth materials that do not undergo change with temperature variations.
FAQs
A ramp is a sloped pathway used to provide access between two vertical levels. It facilitates the movement of wheelchair users, people with mobility conditions, and people on bicycles and other wheeled vehicles.
The maximum slope provided to an outdoor ramp is dependent on the height to overcome (h) and the horizontal length (d) of the plane. Generally, for outdoor ramps, a slope between 10 to 12.5% is desirable for very small heights. This reduces to 8% for heights up to 50 cm, 6% for height up to 100 cm, and 5% for heights up to 150 cm. A slope of 4% is applied for ramps used by elder citizens.
For interior ramps, a 10% slope is allowed to overcome small heights up to 30 cm. For 75 cm height, the slope reduces to 8%, and for 150 cm height, the slope reduces to 6%. The slope reduces to 5% for elderly citizens.
The slope of a ramp is calculated as the ratio of the height to overcome (h) to the length of the horizontal plane(d). The slope of the ramp is also called as gradient or steepness of the ramp. It can be expressed either in ratio or in percentage.
Slope in percentage = (h/d) x 100
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