Sonoma Raceway is taking steps to confine drivers' stunts to the track.
To stop what they say is a growing safety concern, raceway officials are installing a 600-foot concrete barricade at the track's main entrance off Highway 121. That, they hope, will stop evening commuters from making dangerous U-turns and using the entrance as a rush-hour shortcut.
"It's a pain to do it, but we've reached the point where we feel we have to," said Steve Page, the raceway's president and general manager.
Sonoma Raceway is near the intersection of Highways 121 and 37, one of the county's most notorious traffic logjams. Afternoon traffic headed from Marin County to Vallejo can back up for miles as two lanes narrow to one. Some impatient drivers try to skip ahead by getting in the fast-moving left-hand turn lane for Highway 121. They turn left onto Highway 121, and then make a U-turn in the race track's driveway before heading back the way they came and turning left onto Highway 37.
That maneuver has caused at least one crash and many near misses for the 70 people who work at the raceway and the nearly 350 who work in a motorsports industrial park there.
Raceway employee Colin Monahan was leaving work one evening this spring when a driver making a U-turn ran into the back of his new truck.
He wasn't injured; neither was his truck. But the other car had to be towed away, he said.
"I was cautious to begin with," he said. "But now when I see those folks turning I let them go ahead and save their five minutes off their commute."
The situation has developed over the past three years, Page said, calling it a symptom of a larger problem: increasing traffic on Highway 37.
In the evening, the road fills with people who work in San Francisco or Marin County but live in Solano and Napa counties.