Wednesday, June 6, 2012

Round and Roundabout

If you have ever been to a European city, you have seen a roundabout. If you have driven in Washington, DC, you have probably been trapped in one of our many traffic rotaries, or traffic circles as they are commonly called. What’s the difference? 

Modern roundabouts require drivers entering the circle to yield to traffic already in the circle. Old-school rotaries or circles often require traffic already in the circle to yield to cars entering the circle or, worse, have no controls at all over who has right of way.

Confused? Well, of course you are. That’s why old-school traffic rotaries/circles were ripped out en masse from the 1950s onwards and replaced with complicated traffic light arrangements. For example, the Traffic Circle Shopping Plaza in Columbus, GA, sits at an intersection on Victory Drive near the main gate to Fort Benning , but its namesake was demolished in the early 1970s. The replacement was a traffic signal, complete with left turn cycles and endless waits. But the long right-turn ramps hint at its former presence. 

Thomas Circle in its early days---courtesy of the Library of Congress
Unlike the rest of America, Washington kept its circles---with some unusual changes. Here, they were modified with local loops and express underpasses designed with the apparent intention of culling the herds of lost tourists wandering around town. At Thomas Circle, the simple loop was altered with an underpass in the 1940s. Dupont Circle, which dated from 1871, also got an underpass, along with a complicated service road system to separate local from through traffic. Its notoriety was such that it led to jokes in popular Hollywood films such as The American President (Castle Rock Entertainment, 1995), in which Annette Benning’s character warned the President, Michael Douglas, to stay away from it: “It’s murder this time of day.”

Annette Benning warns Michael Douglas about the dangers of traffic circles in The American President (Castle Rock/1995)
Roundabouts differ in that they have an inherent simplicity. Drivers stop at the entrance, look left, and then enter when it’s clear. Because they are looking left, their visibility is greater. The view is less obstructed than if they had to look to the right across the dash. Think of it as halting at a yield sign where a one-way street meets your path and the traffic is moving from left to right.  
How a roundabout works----courtesy of Wikipedia
Note that I say yield, not stop. Typically, traffic entering a roundabout isn’t required to come to a complete stop if conditions are clear. That means fewer backups, which can be particularly handy at freeway interchanges where congestion is most frustrating to drivers (based on my personal observation of horn usage).
Roundabout interchange in the Czech Republic---Photo courtesy Karelj/Wikipedia
That doesn’t mean that everyone is welcoming the roundabouts. In Las Vegas local media picked up on a lot of complaints from the public (and the police) about how confusing a new roundabout was. Local officials responded by increasing the amount of signage to better guide drivers. US drivers are used to traffic lights and stop signs and change is unsettling, as evidenced by one newspaper columnist in the Atlanta area who said,
“So for now, I’ll stand on my soapbox in the center of our downtown and shout NO! No to roundabouts! Rise up, fellow countians – it’s Independence Day once again. The Roundabouts are coming and with them will come higher taxes, job losses, and huge increases in law enforcement overtime.”
Yet old-style intersections bring tremendous risk in the form of high-speed crashes at right-angles. If one driver runs the light or stop sign and hits the side of another car in the intersection (commonly referred to as a t-bone impact), the chances of serious injury or fatality are higher than in a rear-end collision or a sideswiping impact as typically happens in a roundabout. In fact, the Insurance Institute for Highway Safety (IIHS) found that installing roundabouts reduced overall crashes by 39% and fatal crashes by 76%.

The benefits of roundabouts are inducing a horde of cities to embrace them. Columbus, the city that obliterated its traffic circle, is now installing roundabouts in several neighborhoods. One neighborhood, Lakebottom (can you guess how it got its name?) has ten! However, perhaps the US champion of the roundabout is Carmel, IN with over 77 installed and plans for more. The Mayor was inspired by his trips to Britain, which originated the modern roundabout after importing the traffic circle from the US. In other words, the British fixed our traffic circles. 

The one major problem with roundabouts is what to do with pedestrians. If the crosswalks are placed too close to the intersection, traffic exiting the roundabout could collide with pedestrians who may not realize that a vehicle is entering their roadway. That’s a particularly big problem for pedestrians crossing from left to right (as viewed by a car entering the roundabout), since they will have their backs to the exiting traffic from the roundabout.

The solution is to move the crosswalk a short distance away from the roundabout. For low traffic areas, pedestrians will view traffic at right angles and be better able to judge when it is safe to cross. Where the traffic is particularly heavy, signals can be installed. The signals can be a standard traffic light (red/yellow/green) or flashing amber warning signals activated by the pedestrians. 

There is one final argument to be made in favor of the roundabout: it’s cheap. Traffic lights cost money to maintain and operate. The next time you see a traffic light with a burned-out green bulb, think about how much it costs to have a city worker come out with a truck, raise themselves up in the bucket, and replace that bulb. Odds are that a lane will be closed, which will lead to at least some congestion. Worse still, at some point in the near future the process will have to be repeated. And of course, there’s the electric bill to consider.

A roundabout might need a bit of repaving every few years and occasional sign replacement (There’s no fix for bad drivers). That’s less pressure on your wallet via taxes. Who’s against that?

1 comment:

  1. Round abouts are legal games of chicken! And yes Carmel has a ton, but it has made their traffic headaches better.