Silverdale fatality focuses concern on yellow flashing left turns

The in basket: Ian MacKenzie wrote the Road Warrior shortly after a fatal accident at one of Kitsap County’s yellow flashing left turn signals in Silverdale last winter.

While saying he loves the signals and considered them a great benefit to moving traffic, he adds, “after all this time, I am still finding that there are a lot of people out there that are still confused by them and don’t  know what to do.

“As a result,” he said, “they often do one of two things: Sit there and do nothing and the light turns red and they wait for the next green arrow cycle, or they think the light is changing to red so they bolt through the turn in front of oncoming cars. The recent tragedy and death at the intersection of Kitsap Mall Boulevard and Randall Way could easily have been the result of the latter.”

He said the city of Federal Way augments the flashing yellow left turn signals there with a sign with wording to the effect of Left Turn Yield on Flashing Yellow.

“Has or did Kitsap County consider placing signs of this nature to help with the confusion that many still seem to have?  Have there been many accidents attributable to the flashing arrows?” he asks.

Southbound Kitsap Mall Boulevard at Randall Way is the only intersection I know of with adjoining left turn lanes both controlled by flashing yellows. Ian thinks having two cars side by side making the turn on yellow might negatively affect behavior of or visibility for the drivers.

The out basket: Jeff Shea, Kitsap County traffic engineer, says, “Flashing yellow arrows (FYA) are the most popular new technology I’ve seen in the 16 years I have been working in the traffic field.  With just about all new technological innovation though, it brings with it a learning curve and complaints from motorists.

“It is rare when motorists applaud new efforts, even when the new device improves operations and/or safety. In the case of the FYA, we received many positive observations regarding the technology, and comments from motorists indicating that they are effective.
“The ability to turn left when no opposing traffic is present allows them to move through intersections more quickly with less frustration. The previous signal indication used to allow permissive left turns was the green ball over the turning lane. This created confusion for a few motorists as they sometimes interpreted the signal as a protected left turn, rather than a permissive one.  It is permissive in terms that they had to yield to oncoming traffic, whereas protected means they are given the right of way to make the left turn.

“Because of this, we have phased out the green ball for permissive turns because the FYA provides motorists with a much better understanding of the permissive nature of the turn.

“Tens of thousands of motorists navigate through FYA intersections in Kitsap County every day without incident.  (But) FYA signals do not eliminate collisions at intersections.  Misunderstanding signs and signals can play a part in these collisions, but they are not always the primary cause.”

He said the federal Manual on Uniform Traffic Control Devices recently accepted yellow flashing left signals for traffic control and the county adheres to the requirements of that manual.

“Prior to authorizing this new technology,” Jeff said, “extensive research was done by the National Cooperative Highway Research Program. Over a seven-year period, comprehensive research was conducted, including engineering analyses, static and video-based driver comprehension studies, field implementation, video conflict studies, and crash analyses. The FYA was determined to be the best overall alternative to the circular green, and it had a high level of understanding and correct response by drivers.

“We review collision records regularly looking for trouble spots, and we rely on direct reports from the Sheriff’s Office at locations where deputies see frequent collisions. We pay special attention to those areas where new signs or traffic devices are installed, including the FYAs.

“There have been a few collisions attributable to motorists not yielding on a flashing yellow arrow; exactly how many is difficult to tell from the reports. Some of these collisions report a lack of understanding of the signal, others happened when the motorists misjudged how close the opposing traffic was.

“What records don’t show is how many collisions this technology reduces.  Permissive left turns can reduce motorist’s frustration and lessen the likelihood for motorists to make a ‘mad dash’ to get through the intersection before the protected turn sequence ends.

“They understand that they need to wait only for the opposing traffic to clear and then proceed through the intersection, rather than having to wait a full cycle for the next protected turn. The signal may also reduce rear-end collisions by reducing the number of motorists that abruptly stop in front of another motorist for the same reason as above.

“The FYA greatly improves the intersection’s capacity. More vehicles can get through the intersection during the same amount of time.  The FYA … significantly shortens the queue for left turning vehicles. This allows us to shorten the left green signal and give more green time to the other movements at the intersection.  This in itself can reduce driver frustration and possibly reduce overall collisions at the intersection.

“Kitsap Mall Boulevard and Randal Way is a unique intersection in that we have a two left-turn lanes. There have been a few other collisions here including a tragic fatality and we are considering a change.

“We are evaluating installing a sign on the mast arm to remind motorists to yield on the FYA. If any intersection that uses FYA shows high collision rates we will consider this enhancement and other solutions including limiting the times of day for permissive left turns, or eliminating the permissive turn altogether,” Jeff concluded.

About the same time Ian wrote me, Patrick and Sherri Burch also did, suggesting the yellow flashers be replaced by red flashers. We’ll talk about that in the next Road Warrior column