s
s
Sections
Search
We don't just cover the North Bay. We live here.
Did You Know? In the first 10 days of the North Bay fire, nearly 1.5 million people used their mobile devices to visit our sites.
Already a subscriber?
iPhone
Wow! You read a lot!
Reading enhances confidence, empathy, decision-making, and overall life satisfaction. Keep it up! Subscribe.
Already a subscriber?
iPhone
Oops, you're out of free articles.
Until next month, you can always look over someone's shoulder at the coffee shop.
Already a subscriber?
iPhone
We don't just cover the North Bay. We live here.
Did You Know? In the first 10 days of the North Bay fire, we posted 390 stories about the fire. And they were shared nearly 137,000 times.
Already a subscriber?
iPhone
Supporting the community that supports us.
Obviously you value quality local journalism. Thank you.
Already a subscriber?
iPhone
Oops, you're out of free articles.
We miss you already! (Subscriptions start at just 99 cents.)
Already a subscriber?
iPhone
X

The "Follow This Story" feature will notify you when any articles related to this story are posted.

When you follow a story, the next time a related article is published — it could be days, weeks or months — you'll receive an email informing you of the update.

If you no longer want to follow a story, click the "Unfollow" link on that story. There's also an "Unfollow" link in every email notification we send you.

This tool is available only to subscribers; please make sure you're logged in if you want to follow a story.

Login

X

Please note: This feature is available only to subscribers; make sure you're logged in if you want to follow a story.

LoginSubscribe

Petaluma drivers may soon experience a strange new traffic signal — a flashing yellow turn arrow.

Traffic officers have detected an unusual rise over the past three years in left-turn crashes, part of a category of accidents known as "right-of-way collisions" in traffic parlance.

City statistics from 2010 showed a first: right-of-way collisions have become the main factor in most of Petaluma's crashes.

"For as long as anyone can remember in our unit or our department, the primary collision factor has always been speed," said traffic officer Ron Klein.

He said that is also the case throughout California and the rest of the nation.

In Petaluma, most of the right-of-way crashes were at intersections with a specific type of traffic light: a protected-permissive left-turn signal, where a driver is still allowed to turn left after the "protected" green arrow turns to a regular, "permissive" green light.

"It opens the possibility for a driver to make last-minute decisions that can cause an accident," said Larry Zimmer, the city's capital improvements manager.

Most of Petaluma's protected-permissive signals are at intersections that have speed limits of 35 mph or more, Klein said. Collisions at those speeds can be fatal and about half of them involve injuries, he said.

So police sought and received a $441,000 state traffic grant that will fund 90 percent of a project to replace those signals deemed problematic based on collision numbers, speeds, line of sight and other characteristics.

The city will replace all or some of the protected-permissive signals at 26 intersections throughout town, while allowing a few to remain as is.

Some will include a signal new to California and what may be a first for Sonoma County — the flashing yellow left-turn arrow.

Petaluma Boulevard North at Magnolia Avenue/Payran Street had a "higher than expected collision experience involving left-turning vehicles," Zimmer said.

In all four directions, the protected-permissive signals will be replaced with protected left-turn phasing, meaning left-turn drivers will see a progression of green, yellow and red arrows.

Then, once the intersection is cleared, a flashing yellow arrow will light, alerting drivers that they may proceed with caution with a left turn when oncoming traffic is clear.

East Washington Street at Lakeville Street was identified as another trouble spot, with complications brought on because of the railroad tracks that pass through its western leg.

The protected-permissive left turn lights on East Washington will be changed to protected-only lights.

Allan Tilton, a traffic engineer with Whitlock and Wineberger in Santa Rosa, said there will be a slight learning curve for drivers seeing this new flashing yellow signal.

The flashing yellow arrow is already used in several Western states. California has also allowed it as a provisional device, and Petaluma's project should be allowed to proceed after the city notifies Caltrans, Tilton said.

He said the green arrow and green ball signals are confusing for drivers wanting to turn left while trying to judge oncoming traffic.

"As a profession, we've found that we were not communicating effectively to motorists," he said. "When they see just a green ball (when they're) in the left-turn lane, really, what does that mean?"

Recent studies have shown that driver recognition initially was high with the flashing yellow arrow.

"Because it's flashing, it's telling you &‘caution,' as opposed to a solid green ball," he said.

Another change motorists will notice is the configuration of the signal lights. Now, two main types are used for the protected-permissive lights, a 5-light linear configuration and 5 lights in a 1-2-2 stack called a "doghouse."

The doghouses will be replaced with a four-light configuration that includes the flashing yellow arrow.

Traffic engineers have determined that the flashing yellow arrow is also safer for pedestrians. When a pedestrian alert is pressed, the flashing yellow light turns red, reverting to flashing yellow when the pedestrian has cleared the intersection.

No timeframe for the new signals has been determined. Caltrans must approve it before it can go out to bid.

(Contact Staff Writer Lori A. Carter at 762-7297 or lori.carter@pressdemocrat.com.)

Show Comment