ADA Ramp and Curb Ramp Calculator

1. What is an ADA Ramp and Curb Ramp Calculator?

Definition: This calculator determines the design parameters for ramps and curb ramps to comply with the Americans with Disabilities Act (ADA) standards, using inputs like vertical rise and available space.

Purpose: It ensures ramps are accessible for individuals with disabilities, meeting requirements for slope, length, landings, and other features.

2. How Does the Calculator Work?

The calculator uses the following key formula:

\( \text{Ramp Length} = \frac{\text{Vertical Rise}}{\text{Maximum Slope}} \)

Where:

\( \text{Vertical Rise} \): Height to be overcome (inches).
\( \text{Maximum Slope} \):
- New construction: 1:12 (0.0833).
- Existing sites: 1:10 (0.1) for rise ≤6 inches, 1:8 (0.125) for rise ≤3 inches.

Steps:

Input vertical rise, available space, construction type, and direction change.
Validate: Rise and space positive, rise ≤30 inches.
Determine maximum slope based on construction type and rise.
Calculate required ramp length using the formula.
Assess landing dimensions (60” length, 36” or 60” width if direction change).
Check edge protection (required if rise >0) and handrails (required if rise >6” or length >72”).
Verify if required length fits within available space.
Display results in a table.

3. Importance of ADA Ramp Calculations

These calculations are critical for:

Accessibility: Ensuring safe and usable ramps for wheelchair users and others.
Compliance: Meeting legal ADA requirements for public and private facilities.
Design Planning: Guiding architects and engineers in ramp construction.

4. Using the Calculator

Example (Rise = 12 inches, Available Space = 200 inches, New Construction, No Direction Change):

Maximum Slope: 1:12 (8.33%) for new construction.
Required Ramp Length: \( \frac{12}{1/12} = 12 \times 12 = 144 \) inches (12 feet).
Minimum Clear Width: 36 inches.
Landing Dimensions: 60 inches (length) x 36 inches (width).
Edge Protection: Yes (min 2-inch curb).
Handrails: Yes (since rise >6 inches).
Space Check: 144 inches < 200 inches, so the design fits.

Curb Ramp Notes:

Counter slope of adjoining gutters/roads must be ≤1:20 (5%).
Side flare slopes ≤1:10 (10%) for new construction, ≤1:12 (8.33%) for alterations with limited space.
Detectable warnings required for transit facilities or FHWA-funded projects.

5. Frequently Asked Questions (FAQ)

Q: What if the required length exceeds available space?
A: For new construction, consider multiple runs or a platform lift. For existing sites, steeper slopes may be allowed if rise is ≤6 inches.

Q: When are handrails required?
A: Handrails are required if the rise exceeds 6 inches or the ramp length exceeds 72 inches.

Q: What is the minimum clear width?
A: The minimum clear width is 36 inches for all ramps.

Reference
https://www.access-board.gov/ada/guides/chapter-4-ramps-and-curb-ramps/