What is the maximum gradient of the ramp of a dropped curb or curb cutout?

The maximum gradient of the ramp of a dropped curb or curb cutout is typically set at a ratio of 1:12. This means that for every 12 units of horizontal distance, the ramp may rise 1 unit vertically. This gradient is widely adopted in accessibility standards to ensure that ramps are navigable for individuals using wheelchairs or those with mobility impairments, creating a safe and accessible transition between sidewalks and streets.

Using this ratio, a 1:12 slope maintains a manageable incline that is less strenuous for users, promoting greater independence in navigating public spaces. Steeper grades, such as those represented by the other options, can pose significant challenges and risks, as they may become difficult to ascend or descend without assistance. Therefore, a 1:12 slope aligns with best practices in accessibility and universal design.