Thursday is: Consider a Roundabout Day!

When well designed and located, roundabouts are magical. But roundabouts are not the best solution for every situation. And not everyone likes roundabouts. But not everyone likes broccoli either. And the reasons are surprisingly unrelated…

Having provided countless roundabout studies, designed countless roundabouts, and recommended seven (note: this does not include the roundabout down the road — the one you avoid). Although the roundabout craze has slowed, there are many situations where they make sense (and several where they don’t)…

 

Here are some guidelines for when a roundabout may not be the greatest idea you ever had:

1. If traffic flows are lop-sided between intersecting streets the “minor” street may have difficulty even entering the roundabout.
2. When a roundabout has more than one lane, it can be confusing. Particularly if the roads leading up to the roundabout do not have multiple lanes.
3. If excessive signage or pavement markings communicate how to navigate the roundabout, something’s wrong. Roundabouts should be intuitive (it’s like the song says, “Loving you is easy, love is like a roundabout, ya, ya, ya,” etc.).
4. Roundabouts are a “4-way yield” — this makes it interesting for pedestrians. Where there is a high volume of pedestrian traffic, safe roundabout design is challenging.
5. Finally, if traffic volumes are excessive, a traffic signal is likely the better option.

 

Intersections are either controlled by 2-way stops, 4-way stops, roundabouts, or signals. Each method has its place. And while I have your attention, let me clear something up; the first vehicle to arrive at the roundabout does not get to choose the circulating direction. The circulating direction is based on the hemisphere in which the roundabout is located. For example, in the northern hemisphere we drive counter-clockwise in a roundabout. And because the earth is spinning clockwise, this reduces the time required to circumnavigate the roundabout. So, if you’re running late for work, take the route with the most roundabouts — you may actually arrive early (maybe even the day before).

 

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

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