Do roundabouts reduce road hazards and congestion

There is a reason traffic engineers and road planners are wild about roundabouts.

They work.

That’s why roundabouts are showing up in high-traffic areas across the Upstate, replacing two-way and four-way stop intersections.

The South Carolina Department of Transportation (SCDOT) has made the construction of several roundabouts a key part of its plans to alleviate congestion in the highly congested Woodruff Road area of Greenville County.

SCDOT is nearing completion of a roundabout along Highway 29 near the Anderson Jockey Lot and Farmers’ Market.

In Spartanburg County, where the voter-approved penny sales tax supports road projects, lead transportation engineer John Wade is planning for the construction of 14 roundabouts. That’s in addition to the ones recently completed at the

intersections of Flatwood and Bryant roads, as well as Sugar Ridge and Clark roads.

Traffic planners point to several advantages

So why are roundabouts all the rage?

An SCDOT web page puts it simply: “Roundabouts are replacing traditional intersections because they work well.”

First of all, planners say they promote safety.

Because roundabouts require a sharp, though less than 90-degree turn, they generally cause drivers to slow down. They can’t be ignored or missed as easily as a stop sign.

This reduces the likelihood of accidents, according to the experts. And when crashes do occur, they’re less likely to result in injury or death.

That’s because of both slower speed and a less dangerous angle of impact, Wade explained.

“It means crashes will be at an acute angle – maybe a 20-degree angle instead of 90 degrees,” he said.

The SCDOT says, “In national studies, roundabouts have been found to reduce total crashes by 35%, injury crashes by 75%, pedestrian crashes by 40% and fatal crashes by 90%.”

While roundabouts are a strategy for what Wade calls “traffic calming,” planners say they can improve traffic flow by allowing drivers to keep moving and preventing the stop-and-go effect that tends to bog things down.  

Roundabouts also create new opportunities for landscaping enhancements – they can be more visually appealing than traditional four-way stops.

A drawback to roundabouts is that by expanding the overall width of the roadway, “they take up a lot of real estate,” said Greenville County traffic engineer Kurt Walters. Right-of-way acquisition can be a lengthy and expensive process.

And, of course, they take some getting used to for drivers. The most obvious thing is to erase from your mind the idea of a left turn. Stay right, yield as needed, and look for your exit.

For an official set of instructions, visit the SCDOT website.

Roundabouts: the stuff of song

If it seems that traffic planners wax poetic about roundabouts, they are, in fact, the stuff of song:

Many readers will know the Classic Rock staple “Roundabout,” by British progressive rock group Yes.

Music historians say that the lyrics to the early 1970s song were inspired by the band’s travels through Great Britain, where roundabouts have been a common feature of roadways for many years.

Another British band, the new wave act XTC, released “English Roundabout” in the early 1980s. In the song, the traffic configuration serves as the centerpiece of a reflection on modern-day anxieties and pressures.

“Stop the madness,” the song says. “I just want to shout, ‘Let me off o’ this English roundabout.’”

A far lesser-known song is one that my late friend Peter Cooper and I wrote in the late 1990s called “Four Wal-Marts.” The song mentions that “there’s a new traffic circle on the north side of town; my baby likes to go and ride around and around.”

The line was loosely based on a story an old buddy of ours told – that he got bored one night and decided to drive around Hearon Circle as many times as he could. He claimed to have made dozens of loops before being pulled over by a law enforcement officer.

Hearon Circle, situated on Asheville Highway at the intersection with Interstate 85 Business, doesn’t qualify as a roundabout, Wade told me.

“I call it a ‘rotary,’” he said, pointing out that it has too many entry points to meet contemporary standards for roundabout design.

A City of Greenville web page dedicated to the positive attributes of roundabouts adds that they differ from older traffic circle designs because, in part, they are smaller in diameter, promoting reduced speed and greater safety.

While Hearon Circle features left and right lanes with drivers competing for space wherever they can best find it, most roundabouts have only one lane.

But this isn’t always the case.

Wade said Spartanburg County is planning its first multi-lane roundabout at the corner of Cannons Campground and Floyd roads. The design will include a “slip lane” enabling drivers wanting to make a right turn to avoid the main part of the intersection.

Wade said he’s still tackling right-of-way issues and waiting for the SCDOT to complete work on the bridge over Peter’s Creek along Cannons Campground Road. So don’t expect to see the new multi-lane roundabout for at least another year.

A little roundabout history

While circular intersections existed long before, the concept of modern roundabouts, with their safety and traffic flow benefits, is largely attributed to the work of Frenchman Eugène Hénard in the late 19th and early 20th centuries, and further developed by Frank Blackmore in the UK. Hénard pioneered one-way circular intersections in the late 1870s, and Blackmore later introduced the "priority rule" and mini-roundabouts. The circular design of intersections has been a feature of transportation in America since at least the development of Washington, D.C.’s original street grid.

But the first true roundabout didn’t appear in the United States until 1990, when one opened in Nevada, according to the Insurance Institute for Highway Safety.

Wade said he believes Hilton Head was home to the first roundabout in South Carolina.

Mixed feedback

In Spartanburg County, “the feedback has been kind of mixed” on roundabouts, Wade said.

He noted that he’s heard some complaints about altering intersections that had only two-way stop signs. Roundabouts slow down traffic on the previously free-flowing road.

“That’s kind of to be expected,” Wade said. “But, more often than not, reviews have been positive.”

Either way, it looks like the trend favoring roundabouts is here to stay. It will be interesting to see how they eventually impact traffic flow along some of the Upstate’s busiest roads.

And remember: Don’t try to turn left.