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Wheelchair Ramp Definition – Common Terms

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The ADA defines a ramp as an access route that has a slope greater than 1:20 (elevation of 1 inch for every 20 horizontal inches). There are several ADA requirements for businesses, including providing ADA-compliant wheelchair ramps that must follow particular guidelines. These guidelines discuss various parts of the ramp, and some people may not be familiar with all the terms. Below are the wheelchair ramp terms defined and their ADA requirements outline.

Elements of a Wheelchair ramp

Balusters

Vertical posts that are located every 4 inches (or closer) along the sides of a ramp. The balusters are close together to keep small children from slipping through or getting stuck.

  1. Withstand a load of 50 pounds in the horizontal direction applied in one square foot.
  2. Minimum of .75″ x .75″ square tube.

Curb

Also known as a kick plate or wall, a curb is on either side of the ramp to prevent peoples’ feet from slipping over the edge.

Footings

Typically made of concrete with rebar reinforcement, and is placed under each ramp leg to provide stability. 

Guardrail

The outer rail runs along both sides of the ramp at 42 inches above the ramp section. The guardrail’s purpose is to keep people from falling over the edge of the ramp.

  1. Withstands a concentrated load of 200 pounds applied in any direction on the top of the rail.
  2. 42 inches handrail height measured vertically from the walking surface to the top of the rail.
  3. Provided on all open sides of each platform.

Handrail

A smooth, continuous tube that runs along the edges of a ramp and extends at least 12 inches beyond the top and bottom platforms. Its purpose is to support and stabilize people walking on the ramp. (See Figure A)

  1. Withstand a concentrated load of 200 pounds applied in any direction on the top of the rail.
  2. Handrails must be located on both sides of all ramp sections.
  3. Must be continuous along ramp runs even when the ramp makes a 90- or 180-degree turn.
  4. It must be 36 inches high from the walking surface to the top of the rail.
ADA ramp requirements

Platform

The word ‘platform’ is interchangeable with ‘landing.’ They may be placed at the top and bottom of a ramp. Depending on the length of the ramp, additional platforms may be required. (See Figure B)

  1. Carry a uniform live load of 100 pounds per square foot and a concentrated vertical load of 300 pounds in one square foot.
  2. Designed to allow at least a 60 inches diameter area of clearance for a wheelchair to turn around.

Ramp Run

A specified length of a ramp or ramp section. For example, a resting platform is needed after 30 feet of the ramp run. 

Ramp Section

Prefabricated ramps come in ramp sections that are put together to form the whole ramp. Typical ramp sections come in 8 or 10-foot sections. (See Figure B)

  1. Carry a uniform live load of 100 pounds per square foot and a concentrated vertical load of 300 pounds in one square foot.
  2. Have a coefficient of friction no less than 0.50 in the average direction of travel.
  3. Allow a maximum slope of 1:12.
Wheelchair ramp plan drawing showing ramp sections and ramp platform

Slope

The incline of a ramp. Typically, ADA wheelchair ramps have a 1:12 ratio, which means that for every 1 inch of rise in the threshold, 12 inches of the ramp is needed.

ada-compliant slope showing 1 inch of rise to 12 inches of ramp run

Threshold

The bottom of a doorway.

L-Ramp Installation in Ann Abor

ADA Ramp Slope Requirements

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ADA Ramp Slope

The ADA ramp slope must be no steeper than 1:12 (1 inch of vertical rise to 12 inches of ramp length.) The Americans with Disabilities Act states that these criteria must be met for any wheelchair ramp used by the public.

For example, suppose the vertical rise is 10”. To calculate the ADA-required ramp length, multiply the vertical rise (10”) by 12″. Note: once you calculate the ramp length, it is easiest to round up to the nearest whole foot for planning purposes.

ADA Ramp Slope

Ramp Formula

ADA Ramp Slope Calculator

To calculate the ramp length, you will first need to measure the vertical rise (in inches) to the threshold – the distance from the ground to the bottom of the door you are trying to reach. Once you know the vertical rise, you can insert that number into the ADA ramp calculator.

Note: Calculations are made assuming that the ground is completely level. If the ground is not level, learn how to maintain a compliant slope on uneven ground


ADA Ramp Landing Requirements

The ADA states that there must be an additional resting platform for every additional 30′ of ramp length. If the ramp changes directions at the platform, the platform is required to be 60″ x 60″. If the ramp is straight, the platform must be at least as wide as the ramp and 60″ long.

Ramp Length
(Inches)
Ramp Length
(Feet)
Platforms
Required
1-360″1-30′0
361-720″31-60′1
721-1,080″61-90′2
1,081-1,440″91-120′3

Once you calculate the required ADA ramp length using the ADA ramp slope equation above, you can refer to the table below to see how many platforms you require. Each additional platform will add 60” to the overall length of the ramp system.

To calculate the total space the ADA ramp will take up, you must add the required platforms and their corresponding lengths to the required ramp length.

The ADA also states that there must be a 5′ x 5′ clearing at both the top and bottom of the ramp so that people in wheelchairs have a place to sit. Typically, people don’t need to purchase a platform for the bottom of the ramp because the ramp sits on a sidewalk or parking lot with enough space. If you do not have a platform or space at the top of the ramp, you will need to purchase a platform that will add 60″ to the overall length that the ADA ramp system will occupy.


Example: ADA Ramp and Platform Project

Here is a sample project we will walk through to calculate the total length of the ADA ramp and platforms.

The facts:

  • I have a school that needs an ADA-compliant ramp.
  • The door is off the ground, and no existing staircase or platform system leads out from the door.
  • The ground is almost flat, but as I move away from the door in the direction the ramp will go, the ground slopes slightly upwards.

The calculations:

  1. I measure the vertical rise from the ground to the bottom of the door, and it equals 49.75″.
  2. To calculate the length of the ramp at the required 1:12 ADA ramp slope, I multiply 49.75″ by 12, which equals 597″ (49.75′).
  3. After measuring the slope of the ground, I calculate that I only need 575″ (47.9′) to maintain the 1:12 slope. I will round up to the nearest whole foot (48′) to simplify the calculations.
  4. Now I’ll look at the required platforms table above. My ramp falls under the requirements of the second row, so I need to incorporate (1) 60″ x 60″ platform that breaks up the length of the ramp.
  5. I also need (1) 60″ x 60″ at the top of the ramp.
  6. Determine the ADA ramp layout that will fit your application; if you choose a switchback ramp, you will need at least (1) additional platform. For this example, we will use an L-ramp so that it avoids an existing tree.
  7. Below is the ADA ramp layout. In total, the ramp system is 696″ (58′) long.
ADA Ramp Slope Example

Source: 

ADA Regulation 405.2

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