NCDOT makes case for Idlewild/N.C. 51 roundabout

By Josh Whitener

Officials with the N.C. Department of Transportation say a roundabout is the safest, most efficient and cost-effective solution to end traffic woes at the intersection of Idlewild Road and N.C. 51 spanning Matthews and Mint
Hill.

The Matthews Board of Commissioners got a sneak peek Tuesday, May 28, at what the intersection will look like after the state agency converts the intersection to a roundabout. Construction is expected to begin in the summer of 2014, and the intersection will likely be closed to all traffic for six to eight weeks.

NCDOT Division Traffic Engineer Scott Cole gave a presentation for commissioners discussing how roundabouts have been proven to improve intersection safety and reduce traffic congestion during peak hours.

The roundabout at Idlewild Road/N.C. 51 will be a $1.6-million project, with $1.3 million stemming primarily from federal funding, Matthews Public Works Director Ralph Messera said at the meeting. The towns of Matthews and Mint Hill will be required to match the $1.3 million by 20 percent. Because the intersection spans both towns, each town would contribute $130,000, or 10 percent, Messera said.

Two lanes – a left turn/thru lane and a right turn/thru lane – will feed into the roundabout from both the northbound and southbound sides of N.C. 51, Cole said at the meeting. Both sides of Idlewild Road would have a single left turn/thru lane and a right turn-only lane feeding into the roundabout, Cole said.

Cole’s presentation addressed some concerns commissioners and residents have voiced about the impending roundabout as well as common misconceptions about roundabouts.

Cole said roundabouts, like the one planned for the Idlewild/N.C. 51 intersection, typically are 120 to 180 feet in diameter and are the “safest intersection treatment.” They’re designed to accommodate all types of vehicles, including large trucks and emergency vehicles, and also are more “aesthetically pleasing” than typical signaled intersections, he said.

Across the United States, roundabouts have been shown to reduce crashes by an average of 48 percent, Cole said. In North Carolina, roundabouts have reduced crashes at former stop-sign intersections by 41 percent and former signal-controlled intersections by 74 percent, he said.

They also reduce the number of dangerous crashes, Cole said.

From June 1, 2005, to May 31, 2010, there were a total of 51 reported crashes at the intersection, and Matthews Police Cpl. Lori Valdes said previously Matthews police responded to two crashes in the intersection and 16 crashes within 300 feet of the intersection in 2012.

Mint Hill police investigated one crash in the intersection and five crashes within 300 feet of the intersection in 2012, according to Mint Hill Lt. John Rowell.

So far this year Mint Hill police haven’t responded to any crashes within the town’s portion of the intersection, but have responded to eight crashes within 300 feet of the intersection, he said previously.

Because there are fewer conflict points within a roundabout, the majority of crashes in roundabouts are low-angle, low-speed crashes, with virtually no T-type crashes – the most dangerous type of traffic accident, Cole
said.

“People think the traffic signal is the end-all, be-all. But a traffic signal is only as good as the people that obey it, and sometimes people run the traffic signal, and you have the potential for a very serious crash,” Cole said.
Other perks, Cole said, include geometric flexibility, increased safety for pedestrians and cyclists, low maintenance costs and the ability to successfully accommodate buses and bus stops.

Cole said when a roundabout is constructed, the intersection will likely rank a “B” in 2020, while other improvements – such as adding or extending turn lanes and northbound and southbound thru lanes – would likely cause the intersection to rank a “C” or worse by 2020, according to state standards.

Some Matthews commissioners, including Mayor Jim Taylor, were concerned about the length of time it would take to construct the roundabout. Cole said the roundabout could be built with an open intersection, but it would be a lengthier and much more difficult project. He added the NCDOT is planning the project for the summer because there is typically a lower traffic volume during summer months, partly because schools are not in session.

Others were concerned about how the roundabout would impact the surrounding businesses, with Commissioner Suzanne Gulley raising questions about how much right of way would have to be required to construct the
roundabout.

“We haven’t looked real closely as to how much area, how many square feet we’re going to need from those businesses because we have to get a very much more detailed design in place before we do that,” Cole
said.

He added, “I will say that we have no intention of taking a business or altering the parking to a point where their business is not functional.”

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