Patterson Crash: Here's How Those 'Flashing Yellows' Are Supposed to Work

The flashing yellow turn signal at the intersection where Oakland County Executive L. Brooks Patterson was injured in a crash last week was installed four years ago as part of a national effort to make all turn signals the same.

In all, 90 left turn signals in the county now use a flashing yellow arrow during a left-turn sequence. Yet still, there is confusion — and controversy — about how the signals work and why they are used.

As Patterson recovers from his third and final surgery to repair orthopedic injuries suffered in the Friday afternoon crash, Patch offers a tutorial and explanation of the signal at the crux of the incident.

Why they work

The turn signals were introduced to Oakland County as part of a Federal Highway Administration (FHA) mandate toward consistency in traffic signals.

"There was a hodgepodge of different styles of left turn signals all over the country," said Craig Bryson, spokesperson for the Road Commission for Oakland County. 

Michigan was one of few states that used a flashing red arrow for left turns. This flashing yellow arrow was found by the FHA to be safer and better for allowing traffic to move through an intersection. 

Each time the road commission installs or routinely maintains a signal in the county, the yellow arrow is included.

The flashing yellow turn signal allows motorists to slow down, yield and then turn left when there is an available gap in the oncoming traffic. With the flashing red arrow, the motorist was expected to fully stop before turning left.

How do they work?

According to the road commission, the new left-turn signals operate in the following six-step cycle:

1. Steady green arrow: left turns are allowed, opposing traffic has a red signal.
2. Steady yellow arrow: the left-turn signal is about to turn red, so prepare to stop.
3. Steady red arrow: left-turn motorists must stop.
4. Flashing yellow arrow: oncoming through-traffic has a green light; left-turn motorists may turn when there is a sufficient gap in traffic.
5. Steady yellow arrow: the left-turn signal is about to turn red, oncoming through traffic also has a solid yellow signal.
6. Steady red arrow: left-turn motorists must stop.

A detailed explainer is attached to this report or can be downloaded at www.rcocweb.org.

The learning curve

When news about Patterson's crash was reported on Patch, some readers were quick to blame the turn signal.

"Sounds like one of those yellow flashing arrows," wrote Jan Smith in a comment on the . "Some drivers are confused by them and will speed up, thinking it's going to turn red. My dad was nearly killed by such a driver. Maybe we should stick with red and green, so there is no doubt."

"Maybe now that an important person was injured, 'they' will do away with those flashing yellow arrows," commented Carol Lynn.

While Bryson acknowledged the confusion, he said that his agency has not seen a correlation between the new signals and intersection accidents. 

"The FHA went through tons of research, because they wanted to find a universal signal that would be safe," he said. "Like anything new, there may be a learning curve."

The intersection of Walton and Opdyke roads has the third-highest crash frequency in the city of Auburn Hills and ranks 93rd in terms of county crashes, according to traffic data compiled by the Southeast Michigan Council of Governments. From 2007-2011 there were 21.8 crashes per year at that intersection.  The majority of the accidents caused property damage only; 28 caused minor injuries and two caused "incapacitating injuries."

Since 2008, when the yellow turn signal was installed, crashes have remained steady; though they appear to have increased after that year, it's likely because of other factors, Bryson said. For one, along with the converted signal the intersection was widened in 2008, meaning more traffic is traveling through.

"A lot of attention has been put on this particular intersection," he said. "But even though we haven't seen the police report, it seems as though driver error may have been to blame."

According to an Auburn Hills police report, a preliminary investigation showed that the driver of the car that crashed into Patterson's car failed to yield on the flashing yellow turn signal. That car was traveling west on Walton, turning onto southbound Opdyke.

The accident investigation has been turned over the Oakland County prosecutor's office.

Meanwhile, Patterson, 73, remains at McLaren Oakland Hospital in Pontiac.

Have a "get well" wish to offer Patterson? .

 "Brooks has gone through his third and final orthopedic repair,” said Tressa Gardner, director of emergency services at the hospital, in a statement on Wednesday afternoon. "The next step is to start our rehab therapy and the prognosis is good."