The Truth About Lane-Splitting

Tom Roderick
by Tom Roderick

No one can say for sure. yet

Earlier this year, after an Office of Traffic Safety (OTS) survey revealed that nearly half of California drivers were unaware that lane splitting is a legally tolerated practice in the Golden State, the California Highway Patrol (CHP) published Lane Splitting General Guidelines. Meant to bring awareness and promote safety among California’s motorists and motorcyclists, the publication also picked the scab off a festering controversy.

The comments section of any website reporting the survey lit up with opinionated diatribes from critics and supporters alike. Media liaisons from the CHP, Motorcycle Safety Foundation (MSF), American Motorcyclist Association (AMA), among others, were exhaustively quoted (some of whom were contacted for this story). Proponents and opponents debated the validity and safety of lane splitting with no resolve.

These discussions, arguments and accusations are relatively pointless because no empirical data exists on which to base an educated opinion. In fact, no motorcycle safety study ever conducted concludes with any authority the benefits and/or detriments of lane splitting.

This will soon change, however, when a lane splitting-specific study commissioned by the CHP and conducted by the University of California, Berkeley begins releasing reports in early 2014. Dr. Tom Rice, Research Epidemiologist at the Safe Transportation Research & Education Center at UC Berkeley and his team are currently wrapping up data collection in the field, and cleaning and entering the data to be studied.

“The objectives of the project are to examine the practice of lane splitting and its safety implications and to examine helmet effectiveness for specific helmet characteristics,” says Rice.

He and his team have been collecting supplemental data during motorcycle collision investigations for a one-year period. Rice expects to have data on approximately 8,000 motorcycle collisions when finished.

Riding Safe: Crash Avoidance

“When the study is complete we should know if lane splitting is a significant safety risk or if it’s actually safer to be between lanes,” says CHP sergeant Mark Pope. “We looked at the other studies being conducted and decided they will not provide the data the CHP needs in regards to motorcyclists and their behaviors on the freeway,” he continues. “So after the Berkeley study concludes we’ll be able to speak intelligently when people ask if lane splitting is safe.”

The other studies to which Pope is referring is the Hurt Report from 1981, a recent MSF 100 Motorcyclist Naturalistic study conducted in conjunction with the Virginia Tech Traffic Institute, and the Federal Highway Administration (FHWA) Motorcycle Crash Causation Study. None of these specifically targeted lane splitting as a primary element of scrutiny.

The Hurt Report has long stood as the de facto source of information regarding motorcycle accidents in America, largely because no other resource was available until FHWA’s Motorcycle Crash Causation Study was funded years ago and continues to gather data into 2014. That study, like the Hurt Report, is broad-based and will provide little if any insight into motorcycle lane splitting.

Proponents say lane splitting reduces traffic congestion, opponents deny the claim. This image supports the former.

“Lane splitting is theoretically advantageous because there’s no way to statistically disprove it’s safer because there’s been no study from which to pull the information from,” says Dave Thom, a co-author of the Hurt Report.

The MSF’s study is being conducted utilizing motorcycles outfitted with electronic data acquisition systems in California where lane splitting is practiced, but also Arizona, Florida and Virginia where it is not.

“If we discover something about lane splitting it will be scientifically reliable,” says the MSF’s Rob Gladden. Preliminary findings are scheduled to be presented at the International Safety Council Meeting during the AIMExpo in Orlando, October 16-20.

Night Riding

Jim Ouellet, another co-author of the Hurt Report, did publish the study, Lane Splitting on California Freeways, in 2011 but that study combined the limited data gathered by studying freeway cameras from and combining that information with data from the Hurt Report.

“The paper doesn’t prove that lane splitting is safe but that more data needs to be collected,” says Ouellet.

According to Wikipedia: “Lane splitting has been used to describe moving through traffic that is in motion while filtering is used to describe moving through traffic that is stopped.”

One thing the dozens of hours spent watching freeway cameras for three months during rush hour traffic did reveal is that many motorcyclists do not maintain a safe distance to the proceeding vehicle.

“I expected to see riders who weren’t splitting lanes getting rear-ended by cars, but, in fact, it turned out to be that riders who weren’t lane splitting were more likely to be the one striking the vehicle in front of them in a rear-end collision,” says Ouellet.

The Association of European Motorcycle Manufacturers (ACEM) with the support of the European Commission and other partners did publish the Motorcycle Accidents In Depth Study (MAIDS) (Version 2.0 released in April, 2009). Although this study included 921 accidents from five countries over the course of three years, the amount of information gained about lane splitting (filtering, as they refer to it in Europe) was negligible.

What’s the position of the AMA on lane splitting? AMA VP of Government Relations Wayne Allard confirms that a committee has been established to review lane splitting and determine the AMA’s official position.

For now, Allard encourages motorcyclists to abide by the law, but if there is to be a proliferation of lane splitting in the U.S. he says legislation should be at the state level, not the federal level. “The viability of lane splitting varies depending on geography, climate and what that state’s current policies on traffic management happen to be,” he says.

Lane Splitting 101

So far, states other than California, including Nevada, Oregon, Texas, etc., have considered legislation to legalize some form of lane splitting, but none have been signed into law.

“I can’t imagine living in a place where motorcyclists sit in line with cars,” says Thom, a resident of California. “It just seems to bizarre to me.”

Both Thom and Ouellet, whose careers revolve around the scientific understanding of traffic hazards, are lifelong motorcyclists and avid lane splitting proponents.

“As long as it’s done sensibly there’s no reason why a motorcycle should not split lanes,” says Thom. “Clearly there’s a whole lot of room within the word ‘sensibly’ to define what’s safe, prudent and so on, but I think the CHP guidelines certainly help us define sensible.”

According to the OTS study, the majority of motorcyclists intercepted confirmed that they practiced lane splitting when riding on California freeways.

With this amount of motorcyclists reporting to actively lane split, why is the practice disregarded by the MSF? The MSF is currently the contractor to the CHP for administering the California Motorcycle Safety Program (CMSP) which teaches the MSF Basic Rider course. So, right now, it’s an interesting dichotomy where the CHP is offering guidelines to proper lane splitting, while the MSF prefers motorcyclists to not lane split.

“In the classes in California, when the topic of lane splitting comes up, we turn it into a discussion about time and space,” says Gladden. “It’s a learning opportunity about how your time and space cushion is affected by lane sharing.”

To which Sgt. Pope replies, “When you choose to lane split you are giving up a space cushion to your right and left, however, you are gaining a space cushion to your front and your rear.”

Pope is part of the CHP’s Motorcycle Safety Unit, and he’s fond of pointing out that motorcycle safety is an oxymoron. “We understand that riding motorcycles is not about safety, it’s about managing risk,” he says. is a lane splitting advocate website from Oakland, CA.

“It becomes a math problem,” he continues. “You have three things to consider when riding a motorcycle: time, speed and distance, and you’re constantly calculating those three things. If you give up distance, you need to compensate for that in the other two categories.

It’s important to note that the CHP, DMV, DOT and OTS do not advocate lane splitting. “Just like we don’t advocate driving in the fog,” explains Pope. “Is driving in the fog safe? It can be argued that it is not safe, however it is allowed under California state law that if you, the driver, decide that the risk is worth it, then drive in the fog if you want to. And lane splitting is looked at the same way.”

In conclusion, with nothing more really to be said until results from the UC Berkeley study are made public, lane splitting will remain in a state of limbo in California and illegal in the other 49 states. Rice has promised to keep in the loop as data from his study becomes public. Stay tuned and hope for the best!

Update: The AMA Endorses Lane Splitting.

Tom Roderick
Tom Roderick

A former staffer who has gone on to greener pastures, Tom Roderick still can't get the motorcycle bug out of his system. And honestly, we still miss having him around. Tom is now a regular freelance writer and tester for when his schedule allows, and his experience, riding ability, writing talent, and quick wit are still a joy to have – even if we don't get to experience it as much as we used to.

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  • Murphmagictone Murphmagictone on Oct 09, 2014

    Just put some rules around it so that it is allowed if traffic us under 20mph and filtering is allowed at red lights. It works very well. Go to Europe and you'll feel like you're being surrounded by hells angels at every stop light (except half of them are on scooters). Drivers are used to it and don't mind it.

    • Harold O'Brien Harold O'Brien on Jun 16, 2016

      In Europe drivers might be used to it and not mind it but in the good ol' US of A, .. not so much. I live and ride in NY, on Long Island. It's not only illegal most motorist act as if you're stealing from them. Like they're angry that you are getting ahead at their expense. And, as such they have no problem messing with you, .. nonchalantly squeezing over so you can't get by or down right cutting you off. In my nearly 40 years of riding I don't think I lane split more than a handful of times.

  • Maui Taoist Maui Taoist on Sep 16, 2016

    MFS rider coach here.... I would't do it! I might pass on the left or right if I felt boxed in like being tailgated with no escape lane....BUT: Bottom line is you cannot trust cagers EVER they are like a gun an idiot thinks is unloaded but kills him.
    You are not too bright if you lane split all the time... can you say Russian Roulette?