Petaluma collisions up -- first time in 5 years / See graphics

The number of traffic collisions in Petaluma jumped last year but they’re still the second lowest in 25 years, according to the Police Department’s annual traffic safety report.

Other quick highlights:

–The top reason for collisions: Unsafe speed.

–May was the worst month for collisions.

–Fridays had the highest number among the days of the week.

–The 3 p.m. hour was the most dangerous for collisions.

–East Washington Street at Lakeville Street was Petaluma’s most collision-prone intersection.

A total of 691 collisions were reported in 2011, a 9 percent increase from 2010’s 633. Collisions involving just property damage jumped 16 percent in 2011 but the number of injury collisions fell 7 percent.

The graphics included in this column are courtesy of the department’s traffic unit. Click to enlarge.

Police Sgt. Ken Savano, head of the department’s traffic unit, said there was no specific cause for the increase in crashes but the rise did coincide with a drop in the number of traffic citations issued.

“Less enforcement, more collisions,” he said, explaining that officers are getting less time to do traffic enforcement because of cuts in support staff forcing shifts in officers’ assignments within the department.

Savano pointed out that despite last year’s increase, the total number of collisions is far below the average over the last 25 years. Up until 2006 it was common for Petaluma to have more than 1,000 collisions a year. The peak was 1990 with 1,302.

Since 1986, Petaluma has had 26,102 collisions, with 6,352 of those resulting in injuries. Forty people died. The last fatal collision was in 2008 when a DUI driver hit a tree on North McDowell Boulevard, killing a passenger.

Speed was the most common reason cited for collisions, accounting for 147, or 22.41 percent. Right-of-way violations was next at 109, or 16.62 percent.

As for why May had the most collisions last year with 72, Savano indicated it was just the luck of the draw. March had the fewest at 38.

It also apparently was just happenstance that Fridays had the highest, with a total of 140. Sunday was the lowest at 57. But Savano said Friday’s stat has prompted the department to shift a traffic officer to Fridays to step up enforcement.

Savano attributed the 3 p.m. hour as being No. 1 in collisions, with a total of 72, to that’s when schools get out and there’s a sudden increase in traffic as students leave campuses. The safest hour? 4 a.m., which had one collision last year.

East Washington Street at Lakeville Street was the city’s most dangerous when it came to the number of collisions with 10 last year. Savano said that was mostly because of drivers turning left and running into another driver.

He said four of the top 10 collision intersections — East Washington at Lakeville, East Washington at Payran with 8 crashes, Lakeville at East D with 6 and East Washington at Sonoma Mountain/Ely with 5 — all have trouble related to the left-turn traffic lights.

Each of the lights have green arrows that turn to yellow that turn to a green ball. That green ball means drivers can turn left but only when there’s no oncoming traffic. That’s the problem, Savano said. Some drivers get confused and don’t realize they have to yield on the green ball or their view of oncoming traffic is blocked by other cars.

To fix that problem, he said, the city in the next month or two will have changed the traffic lights to have green arrows that turn to yellow that turn to red, thus preventing drivers from turning left except on the green arrow.