Three years ago, Ballantyne motorists became guinea pigs for a newfangled traffic light.
Instead of seeing a traditional green arrow when making left turns from Johnston Road onto Interstate 485, they've dealt with a flashing yellow arrow.
That twist -- perhaps the first major change to traffic signals in 50 years -- is slowly being introduced in the Charlotte area. In a decade or two, it could be common across the nation, one expert said.
The new light was born in 1997 after engineers worried that too many motorists were confusing a green "ball" light as permission to make a protected left turn.
A solid green arrow tells motorists they can make a protected turn -- that they are protected because lights for oncoming traffic are red. A solid green ball means a left turn is permitted, but the driver must yield to oncoming traffic.
The new light replaces the green ball for left turns with a flashing yellow arrow to signal that motorists must yield.
Here's how the cycle of the Johnston Road and I-485 light often works in rush hour:
• Green arrow: protected left turn.
• Solid yellow arrow: Protected left turn is ending. Be prepared to stop.
• Red arrow: stop.
The red arrow then changes for the second part of the cycle:
• Flashing yellow arrow: left turn is permitted, but not protected. Drivers must yield.
• Solid yellow arrow -- All left turns ending. Be prepared to stop.
• Red arrow -- Stop.
The new flashing yellow arrow could startle motorists. The other part of the cycle that's potentially confusing is the steady yellow arrow, which depending on when it's used in the cycle can be interpreted two different ways.
On a traditional light, a solid yellow arrow means you have a second or two to get through the intersection on a protected left turn.
In the new lights, when a solid yellow comes after the green arrow, it means you have another second or two make a protected turn before the red arrow. When the solid yellow arrow comes after the flashing yellow arrow, it means you have another second or two to make a permitted -- but not protected -- left turn.
"We want to take this slow," said Liz Babson, a traffic engineer with the Charlotte Department of Transportation. "We don't want to mess around with this too much."
The city, in collaboration with UNC Charlotte, is collecting data on accident rates at the affected intersections.
The first flashing yellow arrow light in the state was at I-485 and Johnston Road, and went into use in September 2004. The city said there was a reduction in crashes soon after the light was installed, but didn't have any specifics.
The reduction in crashes also could be attributed to more people getting used to the intersection, officials said. .
Last fall, the Charlotte Department of Transportation installed one at the intersection of Fifth and Seventh streets. It recently added the new-style lights at Mallard Creek Church Road and I-85, Sunset Road and I-77, and Reames and Sunset roads.
Trimmers Barber Shop on Sunset Road is about 100 yards from one of the new flashing yellow lights. Barbers have noticed the new signal, but weren't sure what it meant.
"At first it confused me," said Jerome Jolly. "I was wondering why they did it -- it just went from a straight green to a flashing yellow light. It didn't change much."
Said barber Jason Thompson: "At first I thought the light was malfunctioning."
The next Charlotte intersections to get the lights are Charlottetowne and Kings Drive and the intersection of Ballantyne Commons Parkway, John Delaney Drive and Durant Boulevard.
The city may install the new lights on new intersections; most existing lights will wait until replacement is needed. A typical traffic light costs about $1,500to install. A new-style signal costs about $2,100, the city said.
There are 300 intersections nationwide that have the flashing yellow light, according to the Transportation Research Board, a division of the National Research Council.
Crash data showed "safety improved with the flashing yellow," said Ray Derr of the Transportation Research Board.
Solid Green
Left turn protected.
Solid Red
Stop.
Solid Yellow
Left turn protected. Warning, be prepared for a red light.
Solid Red
Stop.
Flashing Yellow
Flashing yellow changes everything. At this point, left turn is permitted, but NOT protected from oncoming traffic.
Solid Yellow
Left turn NOT protected. Warning, be prepared for a red light. Traffic signal aims to end confusion
