Counties and cities around the country have been introducing new means of traffic control that utilize traditional signage and signals but with added functionality. In Kansas City, Mo., the Public Works Department has installed solar-powered stop signs with flashing lights; in Minneapolis, Minn., the local Department of Transportation has incorporated flashing and solid yellow left turn signals.

Kansas City's new stop signs, equipped with LED bulbs that flash in unison at the rate of once a second, were installed at intersections with frequent "sign-running problems," according to The Kansas City Star. It is hoped that drivers will be more likely to obey when confronted with a noticeable flashing sign, which would then provide more safety to pedestrians in these areas.

"People know what to do at a stop sign. That's not the issue. It's 'Did you notice the stop sign?'" says John D. Lee, an engineering professor at the University of Wisconsin-Madison and an expert in driver distraction. "You might not notice if you're texting, for example, or if you're worried about the cyclist riding next to you. The LED lights help to distribute your attention to the critical thing in the environment."

The Minnesota Department of Transportation is rolling out new left turn signals in hopes that they will help speed up traffic flow during low traffic volume and slow traffic, according to The Daily Reporter. During these times, drivers approaching an intersection during a period of low traffic would have the option to turn left after yielding to oncoming traffic.

Solid yellow left turn signals indicate that the driver should come to a full stop before seeking to turn left; flashing yellow turn signals indicate that the driver may turn immediately after checking for oncoming traffic.  

Like the flashing stop signs, these signals are intended to make the driver more aware of situation in the intersection. Yellow signals alert the driver that oncoming traffic will not stop for them.

 "The hope is that there is more clarity to the situation," says Greg Chock, manager of the traffic division of Hennepin County's Transportation Department, another county in Minn. that intends to adopt these Federal Highway Administration-approved signals.

Research indicates that the signs effectively attract drivers' attention and heighten their awareness, according to The Daily Reporter.