Chet Skwarcan is an award-winning engineer, writer, and industry innovator in the field of traffic engineering. He is known for leveraging his creativity, logic, and technology to solve today’s engineering challenges.

Truncated Domes

What Do They Do With All Those Little Nibs?

Pedestrian crosswalks can be found at almost every intersection where pedestrians are allowed. And where you have crosswalks, you often find wheelchair ramps. In fact, wheelchair ramps are installed almost everywhere a walkway encounters a curb. And because most of us do not need a wheelchair or walker (not yet anyway), many ramps also include truncated domes.

These domes are tiny little hemispheres with the tops cut off. They not only provide tactile feedback and friction but the contrasting color enhances ramp detectability and the presence of an impending crosswalk leading to an impending street (containing impending cars and big trucks).

And in areas where pedestrians are crossing a street but not at an intersection, an effective technique is to raise the street instead of lowering the sidewalk. This solution is called a raised crosswalk. In other words, rather than ramping the pedestrian, the “ramps” are constructed on the roadway and consequently ramp the vehicle. The design of a raised crosswalk is flexible — the inclination angle, the length, the width, the height, arrival & departure times, can all be adjusted to provide a comfortable experience for vehicles driving the appropriate speed (and an uncomfortable experience for vehicles driving the inappropriate speed). They are also snowplow-friendly making them a superior alternative to speed bumps.

Raised crosswalks have the added advantage of slowing traffic to a safe speed at crosswalks — a form of traffic calming. This is particularly an excellent solution in neighborhoods and near schools to provide wheelchair access AND safer/slower traffic where pedestrians abound. By pedestrian, I am referring to people/kids (e.g., my wife and I had four pedestrians — so far).

Note: this column will originally appear about three months from now but it’s repeated early due to recent questions about truncated domes and all those little nibs.


Chet Skwarcan (traffic engineer, author, unique insights) with over 25 years of traffic engineering experience — online help available at