Every California driver has seen it: A motorcyclist snaking through a line of traffic at a stoplight or zipping past cars on the freeway.

The practice is called lane-splitting or lane-sharing. And while some drivers suspect it’s illegal, California has always allowed lane-splitting. In 2016, former Gov. Jerry Brown signed legislation that defined the practice and tasked the California Highway Patrol with providing guidelines for riders.

But CapRadio listener Matt Champion wanted to know: “Are our roads safer now that this law has been in effect?”

The short answer: It’s unclear. Many motorcyclists argue lane-splitting takes them out of harm’s way. But there’s limited research on the topic, and available data doesn’t offer concrete answers. 

Douglas Wood has been riding motorcycles for nearly 20 years and has always split lanes. The Sacramento-based rider says he typically does it at stoplights and when congestion on the freeway brings traffic below 25 mph.

He argues it gets him to his destination quicker and is safer for riders.

“You’ve all seen it on the side of the road, where two or three [cars] rear-ended each other,” he said. “If a bike was between there, he doesn’t have a chance.”

CHP Sergeant Joe Godman oversees the agency’s motorcycle safety program. He was part of the motorcycle patrol in the Bay Area and says he split lanes on a daily basis. He says it can mitigate some dangers for riders — such as being rear-ended. It can also help patrol officers get to incidents quicker.

But he says it’s unclear if it’s safer or more dangerous than riding within the dashed lines.

“I don’t know of any statistical data that indicates that one way or another,” Godman said. 

In 2017, according to data from the National Highway Traffic Safety Administration, there were 578 motorcycle fatalities in California — the most in the past 10 years. The data, however, does not include the cause of the crash. 

Some research suggests lane-splitting, if done prudently, is a safe option for motorcyclists. A 2015 study from UC Berkeley found lane-splitting is relatively safe if the surrounding traffic is traveling less than 50 mph, and if the rider does not exceed the flow of traffic by 15 mph. The study also found motorcyclists who split lanes are more likely to use better helmets and travel at lower speeds.

Godman says some riders do split lanes recklessly, and that they shouldn’t be surprised if they see red and blue lights in their mirrors. 

“There are lots of factors that will go into creating an unsafe condition for splitting-lanes and whether or not an officer will take enforcement action,” Godman said. “[It’s] dependent on weather, traffic flow, congestion [and] speed.”

Wood agrees that lane splitting isn’t a free pass for riders to do whatever they want.

“When the flow of traffic is the speed limit … and guys go flying by at 75, 85 mph,  I’m sure that gives us a bad name.”