Motorcyclists' practice of lane-splitting is legal in California, but nearly half of drivers don't know that, and some of them admit trying to stop bikers from riding between lanes of traffic, a new state survey shows.

In conjunction with declaring May to be Motorcycle Safety Awareness Month, the California Office of Traffic Safety has published the results of its first-ever survey (PDF) on the thoughts of both motorcyclists and automobile drivers on lane-splitting.

The office called the practice -- squeezing between two lanes of slower vehicle traffic headed in the same direction -- "the subject (of) controversy and confusion."

It saves motorcyclists time in traffic jams, but it can startle or annoy "regular" motorists.

Only 53 percent of drivers know that lane-splitting is legal, according to the survey results. Seven percent said they have tried to prevent a motorcyclist from splitting lanes.

Meanwhile, 87 percent of motorcyclists said they split lanes.

The survey included results from 560 motorcyclists (PDF) and 733 passgenger vehicle drivers (PDF).

The Office of Transportation Safety said the key to safe lane-splitting is for motorcyclists to be aware of traffic speeds, speed differences, spacing and lane changing patterns of surrounding traffic.

The main thing bikers do to make lane-splitting unsafe is ride too fast, the office said.

The office reminded drivers to "share the road" with motorcyclists. Accidents affecting motorcyclists have been on the decline since 2009, but federal research shows that motorcyclists are 39 times more likely than passenger vehicle occupants to die in a crash, the state office said.

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