MoDOT: Flashing yellow arrows safer for drivers

Thursday, June 3, 2010 | 5:13 p.m. CDT; updated 9:22 p.m. CDT, Thursday, June 3, 2010

COLUMBIA — If there’s one thing drivers learn to dread, it’s the left-hand turn — crossing at least two lanes of oncoming traffic, questioning who has the right of way, frustrated when the left-turn arrow flits rapidly to red.

Now, folks at the Missouri Department of Transportation hope turning left will be a little easier with the help of flashing yellow arrows.

Starting in March, MoDOT began putting in new left turn signals at 14 intersections around Columbia, including several on College Avenue. The new signals are being installed after a national study found flashing yellow arrows are easier for drivers to understand. MoDOT has a five-year plan to install the lights at about 100 intersections along state highways within Columbia.

Studies have found the traditional left-turn yield on green can cause crashes because some people don't understand they must yield, said Jason Sommerer, MoDOT senior traffic studies specialist.

"The idea was to get an indication that makes more sense to drivers," he said.

Sommerer said drivers who were confused upon approaching flashing yellow arrows would stop and wait to see what they were supposed to do rather than speed through the light, which was often the case with the green ball system.  

Rebecca Geyer was a principle investigator who worked on the 2008 MoDOT study, "Assessment of Driver Recognition of Flashing Yellow Left-Turn Arrows in Missouri."

“It takes a while to get used to them, its’s kind of like a roundabout where people are confused at first, but when they watch other people, they can figure it out and realize it's efficient,” Geyer said.

The study was conducted in St Louis where a few intersections had been retrofitted with the new turn signals. More than half of respondents answered correctly when asked what to do when making a left turn at a flashing yellow arrow. Even so, the study suggested the new signals be implemented with caution because results showed  drivers who had not seen the arrows before answered correctly only 74 percent of the time.

"It's important to note that when the study was conducted the instructional signs on the turn signals weren't in place," Geyer said.

With no sign explaining to drivers how to proceed through the new signals, it followed that drivers would be confused. Sommerer said some drivers even called MoDOT to report that lights were broken when in fact they had just been equipped with the flashing yellow arrows.

Sommerer said MoDOT concluded that explanatory signs are necessary. MoDOT also tried to educate the public.

“We had public meetings to explain the new lights, but not many people attended,” Sommerer said.

“They start out confusing, but over time they increase traffic flow,” said Mack McCallister, who works at Hampton Inn & Suites at Stadium Boulevard and College Avenue, where there is a yellow arrow light.

Several cities across the nation are using flashing yellow arrows, and many have heard positive feedback. Fayetteville, N.C., has had 20 such signals for about three years, traffic engineer Rusty Thompson said, and it plans to install 20 more.

“We’ve had an overwhelming positive response,” he said. “People have begged to have them installed in other locations.”

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robert link June 4, 2010 | 9:00 a.m.

I think a problem that some drivers have is that they interpret the flashing light as an about to expire "protected left turn" and hurry to complete their turn. This puts them in the dangerous position of turning left into green light oncoming traffic. Perhaps more education is required up to and including drivers license testing.

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