California is the only state where lane-splitting is legal. Here is what lane-splitting looks like from a car on a busy Los Angeles highway. (The Washington Post)

LOS ANGELES — Let’s say you’re stuck in traffic in Los Angeles, which is a frequent and annoying experience, but also the price you pay for living in one of the greatest cities on earth, or visiting here.

Suddenly, a motorcycle roars past, so close to your car that you think his kneecap is going to whack your side view mirror. You watch with amazement as this helmeted daredevil threads through two lines of cars, sometimes weaving as traffic shifts lanes. Then you look in the rear view mirror and see a line of motorcycles coming your way, about to do the same thing. You wonder where the cops are. And then you see a California Highway Patrol motorcycle officer zipping through traffic the same way.

This is lane-splitting, California-style. Also known as lane-sharing, filtering, or stripe-riding, lane-splitting allows motorcyclists to cut through slow-moving traffic by cutting between cars. It’s wild, it’s scary, it’s fascinating and – despite how crazy it looks – it’s legal in the Golden State. The big surprise is that, within limits, it’s also safe, at least according to one of the few studies that’s looked at the practice.

And that’s why the Washington region area should consider allowing it here.

“There’s many opinions about it and very little data,” said Chris Cochran, a spokesman for the California Office of Traffic Safety, which conducted a study of lane-splitting. “Out of that study came the data that lane-splitting in and of itself — when done in what we refer to as in a safe and prudent manner — is no more dangerous than regular motorcycle-riding.”

Motorcyclists have long claimed that the practice is safer than remaining in a lane in stop-and-go traffic because it  lowers the risk of being rear-ended and allows them to maneuver to open road. It also saves time, obviously. But it also means riding much closer to other vehicles.

The subject comes up a lot in riders’ forums. Although it’s illegal in most jurisdictions, many motorcyclists admit to lane-splitting when highways become parking lots, even if it means risking a traffic ticket. They say law enforcement generally overlooks the practice,  unless the biker blazes through.

The most negative reaction usually comes from angry drivers in cars. For them, it’s not only startling to have a motorcycle whiz by so close, it can seem dangerous. And some car-bound motorists just don’t like it that motorcyclists are cutting to the head of the line.

Right now, California is the only place lane-splitting is allowed, Cochran said. State law there, unlike in other jurisdictions, is silent on the issue. That could change soon, however, as the California State Assembly considers legislation to recognize and allow lane-splitting under certain conditions.

California, by virtue of its size and climate, has a sizable number of motorcycles, and its pack is growing. The number of registered motorcycles in California has increased by about 29 percent in 10 years, from nearly 700,000 in 2005 to nearly 900,000 in 2015, Cochran said.

The number of accidents has also risen. In 2013, which is most recent year of easily available data, there were 463 motorcycle fatalities and 11,946 seriously injuries, Cochran said.

His agency decided to look into lane-splitting because of its widespread practice there and commissioned studies on the subject, including one on motorists’ attitudes toward lane-splitting and another on safety.

The safety study – which was conducted by the Safe Transportation Research & Education Center at the University of California Berkeley — found that lane-splitting, when done within certain limits, is no more dangerous than riding a motorcycle otherwise. The study examined 5,969 crashes between June 2012 and August 2013 using enhanced data-reporting by police. It found a lower rate of fatalities among lane-splitting motorcycles and less serious injuries overall.

The study found that most of the bikers who were lane-splitting were doing so during rush hour. They were also traveling slower and less likely to be using alcohol or carrying a passenger.

But the study also found that the circumstances of lane-splitting are critical, especially the speed differential between the motorcyclist and the surrounding traffic. The overall speed of traffic flow is also important. So long as a motorcycle is traveling no more than 15 mph faster than the surrounding traffic, and the traffic all together is moving at 50 mph or less, lane-splitting can be done safely, the study says. Going above 50 mph, however, invites trouble.

“The faster you go as a cyclist and the faster the surrounding traffic is traveling, the more crashes there are, and the more severe the crashes that result are,” Cochran said.

Following the Berkeley study, Cochran’s agency posted lane-splitting guidelines on its website. So did the California Highway Patrol. But those guidelines came down after controversy ensued about whether they amounted to “underground regulations” that had been created without public input. They also clouded efforts by the CHP to crack down on lane-splitters who were doing it recklessly, California officials said. (Copies of the guidelines can still be found online, such as here.)

So Assembly member Bill Quirk (D) stepped in. Quirk, an astrophysicist who has worked for NASA (and doesn’t ride a motorcycle), said through a spokeswoman and in a followup interview that there are benefits to allowing the practice to continue.

“There’s a safe way to do it, and an unsafe way to do it,” Quirk said in an interview Thursday. “Most notably, it allows motorcyclists to drive defensively in congested traffic to avoid being rear-ended. However, lack of information on how it should be done safely means different people lane split under safe conditions while others lane split at high speeds with little regard for safety.”

Quirk said his bill — which initially set speed limits and was written in a way that some interpreted as a potential crackdown on lane-splitting — has since been modified. For one thing, law enforcement officials and others urged him not to codify the practice without more research, Quirk said. The measure now would simply recognize the practice and authorize the CHP and other state officials to come up with guidelines for lane-splitting.

Quirk said his bill has the backing of law enforcement, motorcyclist groups, and the insurance industry. (The CHP – whose motorcycle officers have been seen lane-splitting on their department-issued BMW’s – is prohibited from commenting on pending legislation, a spokeswoman said.)

The California measure to recognize and control lane-splitting makes sense, even if I’m not so sure I’d do it on my motorcycle the way so many Angelenos do. It’s also something that other jurisdictions, including the District, Maryland and Virginia, should consider too.

Should motorcycles be allowed to split lanes?

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If you want to see what it looks like from a biker’s point of view, here’s some YouTube video posted by a motorcyclist who said he was lane-splitting on LA’s Interstate 10:

–This post has been updated.