According to the U.S. Department of Transportation Federal Highway Administration guide “Accessible Sidewalks and Street Crossings“, diagonal curb ramps are NOT RECOMMENDED.
The reasons the FHA guide gives for not using this type of curb ramp include:
- Pedestrian with a vision impairment can mistake a diagonal ramp for a perpendicular ramp and unintentionally travel into the intersection because it is not aligned with the crossing direction.
- May conflict with motorists who are traveling straight or turning if corner radius is small.
- Directs wheelchair users into the intersections. Requires wheelchair turning at the top and bottom of the ramp.
I’ve long disliked diagonal ramps because:
4. Drivers cut turns extra shallow and run right over the end of the diagonal ramp. Cars running up over the sidewalk with no curb to “curb” them is bad! Here is my ridiculous illustration of this problem. The green blob with two black circles is supposed to be the back end of a car.
5. When a pedestrian turns to face the direction of the ramp path, any drivers in the area will have no idea which direction the pedestrian is about to cross. Confusion with pedestrian-driver interactions is bad!
This morning while walking to work in a fresh fall of a half a foot of snow, I learned a 6th reason to not use diagonal curb ramps.
6. Diagonal curb ramps require pedestrians to veer out of a straight path of travel to use the ramp. If the curb area is obscured by snow, and a pedestrian takes a rational, straight path of travel, the curb outside the ramp cut becomes a trip hazard.
Here is a ridiculous series of illustrations of me this morning, using an image of this type of “undesirable ramp location” from the Colorado DOT “Curb Ramp Designers Resource”, which has a different illustration angle than the FHA guide.
Me, walking in the street within the “crosswalk” area (green lines) towards the sidewalk. Hidden under all the snow is the curb ramp as well as elevated curb, indicated by red lines.
Ohhhhh noooo! I catch my toe on the elevated curb next to the ramp.
The toe-catch causes my forward motion to rotate downwards.
BLAP! I land on my arm, tweaking my elbow in the process.
Unfortunately, this type of diagonal curb ramp is being installed extensively throughout the city where I live. I appreciate that there are now more curb ramps where there used to be steep curb dropoffs, but I really wish the recommended two perpendicular curb ramps were being installed instead. (Also, some of the diagonal curb cuts are being installed with completely inappropriate angles, which would make it extremely difficult if not impossible for a wheelchair user to navigate.)
Here’s an illustration of perpendicular curb ramps from the FHA guide:
For another perspective on diagonal curb ramps, see this blog post from Americans with Disabilities Act (ADA) specialist and wheelchair user Michele S. Ohmes.