Flashing yellows leave some Boulder drivers seeing red

If you drive around Boulder often enough, you have been at a left turn, looking at a yellow flashing arrow and waiting for your chance.

And now, drivers around the county are likely to start seeing more of these lights as well, as the yellow flashing arrow has replaced a green circle as the preferred method of signaling a driver can make a left turn only if the coast is clear.

Joe Paulson, a transportation engineer for Boulder who works with signals and lighting, said the city now has the yellow flashing lights at 96 different approaches at 40 of the 141 signaled intersections within the city.

Paulson said that Boulder was one of the first cities in 2004 to adopt the flashing lights as a way of signaling a driver must yield on a left turn rather than a green circle after federal studies showed the yellow arrow was safer.

“It‘s a more intuitive display,” Paulson said. “The circular green, which has been in place for decades, means yield on a left turn, but people inherently interpret green as ‘go.‘ They think that means left turn can go now, we don‘t have to yield but it‘s a mistake and a dangerous one.

Paulson said on the other hand, people shown the yellow flashing arrow, if they didn‘t immediately interpret its correct meaning, tended to think it meant they could not turn.

“That‘s wrong, but it‘s a safer wrong,” Paulson said. “They may annoy the driver behind them, but they will not cause a crash, so it‘s inherently safer from that perspective.”

‘I get it now‘

Paulson said that in 2009 the Federal Highway Administration officially made the yellow flashing arrow the standard, which means all lights that are installed or updated from here on out will have to use them. Paulson said that means more and more people will see them even outside of Boulder.

But more than the debate about what signal is used to convey the message, some in Boulder have argued that left turns that require drivers to yield are dangerous in general. Two people have written letters to the Daily Camera in recent months, including , who says he was initially very confused by the intersection at 30th and Pearl streets.

Benezra noted that at times, he had a yellow flashing light for the left turn lane but a red light for through traffic, and mistakenly assumed the oncoming lanes had the same configuration. But at times, Benezra said, oncoming lanes had a green light for through traffic.

“I think that‘s where the confusion happens,” Benezra said. “I get it now, when I see a yellow flashing, I‘m really, really cautious. But it‘s just confusing when you don‘t realize the other side has a straight-through green and your side has a straight through red.”

Another reader, Kitty Brigham, about drivers concentrating so hard on trying to beat oncoming traffic that they lose track of pedestrians and cyclists.

“So very hazardous, with drivers trying to make a sudden and hasty left-hand turn against oncoming traffic during their green light,” Brigham wrote.

Paulson said intersections with left turn arrows have three different cycle configurations. At permissive intersections, like 30th and Colorado Avenue, the left turn is always either a red or a yellow flashing arrow, which means drivers must always yield when making a left.

Protected intersections, like Foothills and Arapahoe, are only either red or green arrows, which means that when drivers make a left turn, they can do so knowing they have the right of way.

Then, there are what Paulson said are permissive-protective turns, where the left turn signal can either be a green arrow or a yellow flashing arrow based on time of day or traffic flow.

Paulson said the decision about which cycle configuration to use at every intersection takes into a number of factors, including speeds, number of lanes and the amount of traffic.

“We look at a number of factors to decide what form of left turn to provide,” Paulson said.

Permissive only is the most time-efficient of the three configurations — “You‘re slicing the pie that is time into fewer slices” Paulson said — but protective turns can be safer, and Paulson said it is likely the city would lean towards a slower but safer light cycle at intersections with heavy foot or bicycle traffic.

“We‘re taking a hard look at how we make those left turn decisions,” Paulson said. “We will probably emerge from that process with a decision-making methodology that will more often provide protective- permissive and protective-only turns in locations of higher pedestrian and cycling activity.”

Ahead: increased comfort?

Paulson said that fewer permissive left turns tend to create slower intersections, which lead to other safety problems like turn lanes backing up into through-traffic or cars cutting through neighborhoods. But leaning towards preventing crashes in the intersection would fit with the city‘s , which seeks to eliminate fatal and injury crashes.

“Because of the vulnerability of cyclists and pedestrians, when they do get in crashes they tend to be more severe,” Paulson said. “We are already factoring in the presence of pedestrians and cyclists, but we may sort of double-down on that and look to provide even more protective turns.”

Sue Prant with Community Cycles in Boulder said she thinks having a light cycle that gives pedestrians a time to cross without having to worry about vehicles is the best option.

“That way you move bikes and pedestrians out of the way first,” Prant said. “The automobile doesn‘t have to figure anything out. It‘s just a short few seconds, but it gives that security in an intersection.”

But ultimately, Paulson thinks that with education and more cities installing the yellow flashing lights, drivers will become used to them.

“I think what we‘ll see is increased comfort, both nationally and locally,” Paulson said. “There is always discomfort in change and discomfort in uncertainty. But as people become more experienced, there is going to be some comfort and familiarity.”

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