UC Berkeley Study Shows Lane-Splitting to Be Safe

06/03/2015 @ 12:30 pm, by Jensen Beeler38 COMMENTS


The University of California Berkeley has finished its study of lane-splitting in California, and the results are encouraging for lane-splitting proponents.

Researchers, led by Dr. Thomas Rice of the Safe Transportation Research and Education Center (SafeTREC), reviewed nearly 6,000 motorcycle-involved traffic collisions between June 2012 and August 2013, including 997 in which the riders were splitting lanes at the time of the crash.

The big takeaway from this research is that when done reasonably, lane-splitting is just as safe as riding a motorcycle. As such, one of the more important insights found by Rice and his team was that motorcyclists can travel up to 15 mph faster than the flow of traffic with no statistical increase in crashing.

This study will be important for shaping the conversation about lane-splitting, not only in California, but throughout the entire United States. It’s no coincidence then that California’s current attempt to codify lane-splitting mirrors these findings from UC Berkeley.

The entire UC Berkeley findings can be read here, but the bullet points are as follows:

  • Lane-splitting is safe if done in traffic moving at 50 mph or less, and if motorcyclists do not exceed the speed of other vehicles by more than 15 mph;
  • 69% of lane-splitting motorcyclists were exceeding the traffic speed by 15 mph or less; speed differentials up to 15 mph were not associated with changes in the frequency of injury;
  • Compared to riders who were not splitting lanes, lane-splitting motorcyclists were markedly less likely to suffer head injury (9% vs. 17%), torso injury (19% vs. 29%) or fatal injury (1.2% vs. 3%);
  • Lane-splitting riders were significantly less likely to be rear-ended than non-lane-splitting riders (2.6% vs. 4.6%);
  • Lane-splitting motorcyclists were more likely to be wearing a full-face helmet than other motorcyclists (81% vs. 67%);
  • Compared to other motorcyclists, lane-splitting riders were more often riding on weekdays and during commuting hours, were using better helmets and were traveling at slower speeds;
  • Lane-splitting riders were less likely to have been using alcohol.

“These new findings bolster our position that responsible lane-splitting is a safe and effective riding technique that can be beneficial for riders and motorists alike,” said Wayne Allard, AMA Vice President for Government Relations.

“Lane splitting eases traffic congestion by taking motorcyclists out of the line of cars and trucks. And the practice increases safety by allowing motorcycle riders to avoid the risk of rear-end collisions in stopped or slow-moving traffic.”

As loyal A&R readers already know, motorcycle lane-splitting is a common practice in many countries throughout the world – particularly in the highly urbanized areas of Europe and Asia.

A way to alleviate traffic congestion and reduce the risk of crashes, lane-splitting for some reason has not been a part of the American vehicle landscape, with California currently being the exception.

With this information in-hand though, hopefully lane-splitting proponents can begin to challenge the status quo opinion that lane-splitting is unsafe. At the very least, the cold hard facts can stand against the opinion-fueled stigma, and we can begin to change those perceptions with reality.

Source: AMA

  • Joe Perez

    I live in California, and I lane-split frequently on the route between Santa Barbara and 1000 Oaks. I’m glad lane-splitting is considered legal in this state (though not codified as such). I’ve read the U.C. Berkeley summary findings. It is encouraging. That said, I do NOT think lane-splitting at 50 mph is smart in most situations. At 50 mph a rider is moving 73.3 feet per second. Human reaction time (in traffic situations) is typically about 0.7 seconds (“After a person becomes aware of a dangerous situation, some time will elapse before he can take evasive or defensive action against it. This time interval, commonly called the reaction time, has been found to be roughly 0.7 seconds for all normal persons, regardless of their background and training. Source: http://www.technology-assoc.com/articles/reaction-time.html). So this means a biker will likely travel 50 feet or so before he can even take action. If he encounters an unexpected lane-changing auto, theres’s very good chance of an impact. Now if you take the “bullet points” to mean its OK to lane split at 65 mph with cager traffic moving at 50 mph, I say that’s just nuts! Too little time to react, too much risk.

  • It’s the speed delta that’s the most important factor. Yes, you’d be going 65 mph, and traveling 95.3 ft per second, but the car in your scenario is traveling at 73.3 ft per second as well.

    If there’s a sudden lane change by that car, the reaction time in distance is still only 14 ft.

    Could there still be a crash, sure. But it’s not the nuclear scenario you suggest, and the research supports that math.

  • Just to add, I’ve found lane-splitting at higher traffic speeds to be much safer than slower speeds. Stop and go traffic has cars scrambling to find the quickest lane, making quick lane changes. At higher speeds, cars are more set and predictable.

  • Christopher Ring

    Not to be a hater but I think the author is picking and choosing what data to include in order to advocate his position that lane splitting is a sound practice. What the study say is that lane splitters today are half as likely to be rear ended as other riders but are twice as likely to rear end someone else. So he’s choosing to ignore the type of accident which is almost 5x more likely to occur (254 incidents for being rear ended vs 1157 incidents where the rider rear ends another vehicle).
    in order to ride safely you need to anticipate danger and leave yourself enough room to adjust for that danger. You can say its easier to anticipate danger if you lane split because you’re blind spot behind you isn’t where traffic is, however there is much less space to avoid the danger if you are between lanes. In low speed situations like below 30mph in stop and go traffic it probably is safer however I don’t ever see it being safe at highway speeds there is just no space to get out of the way.

  • CortexUK

    I don’t care. I ride (recreationally only) and I oppose it. I will not do it.

  • imprezive

    So you are opposed to safer riding conditions for other riders? Why?

  • Uncommon Sense

    I certainly think filtering to the front of the line at stop lights and splitting with slow moving traffic should be legal. However, I can’t really see a logical reason to be splitting lanes at 50mph or greater as that means traffic is moving along just fine.

    This morning on my commute, I could easily see how lane splitting would make life easier as probably 3/4s of the 9 miles on the highway cars were probably going at best 30mph. It opened up a few spots where speeds get backup to 60mph and I’d see no point in splitting then.

    I do agree you have to be on your toes for cars jumping in and out of lanes when traffic is going slow, but splitting at highway speeds leaves no room for error imho.

    The squid factor is why a lot of cagers dislike it. All it takes is some guy on a stretched chromed out Busa to be splitting recklessly to ruin for everyone.

  • crshnbrn

    I think drivers would be more against motorcyclists filtering to the front at stoplights, because we could beat them to the next red light and be in front of them. Where on an expressway, motorcyclists could be well on down the road. Drivers wouldn’t perceive a motorcyclist filtering on an expressway as merely getting ahead of them, but truly relieving traffic congestion, which is what every motorist should want.

  • Manny Fresh

    The great thing is that you can exercise your freedom of choice not to lane split, but no need to oppose it or eliminate it as an option for those that chose to do so, especially with the data suggesting at worse that it isn’t any more dangerous overall and in fact safer in many more situations than not.

  • Daniel Croft

    I don’t usually split at higher speeds because, as the commenter below mentioned, that usually means traffic is moving fine.

    Having said that, I think that speed differential is not only the most important factor when splitting but should in fact be the primary and preferably only legally codified portion.

    IMO any law that was introduced should be that splitting is only permitted up to 10 or 15 mph (or whatever) above traffic speed and that’s it. The speed limit takes care of the maximum speed.

    Efforts to limit the max speed is unnecessary given that there’s a speed limit AND the police are still free to ticket someone for dangerous driving. I don’t split at high speeds, for the record, and do my best to follow the CHP guidelines. I’m respectful to other motorists and will actually move to share a lane in the HOV lane when I’m the slow guy.

  • Hpinto

    Just look to Europe where in almost all countries lane-split is legal. I ride I bike in Europe for more than 20 years and for me doesn’t make any sense not do it, specially when you are on stop and go. That the greatest advantage of the “bikes”. It danger, but you as a rider have to evalute every situation. Rigth now I’m in US, MI, and I just did an endorsement but due to the conditions of roads I will not ride a “bike” here. And it is true that the drivers change line without signals, much more often than in Europe.
    In other hand even it is legal doesn’t means that you needed to do it. It depends in your experience, motorcycle that you are ride and your aceptance to take the risk!

  • Jack Hammer

    Then don’t do it. But it’s not your business if others do.

  • James Norwood

    If you want a real sense of the safety f lane splitting, do what I did. Spend 10 years lane splitting in California and then move to a state with brain dead cage drivers (like, say, North Carolina) and see how incredibly vulnerable and unsafe you feel. As odd as it seems, once you are accomplished at riding between cars, you can use that space to avoid a lot of danger. When people have no regard for your safety at all, the safest thing you can do is find ways to stay out of their way. That space exists between their sound proof rolling phone booths.

  • Jeromy

    I am extremely skeptical that opposition to lane splitting has anything to do with safety. I have only heard people getting pissed about how “unfair” it is, and that if they have to sit in traffic so do you. The road rage, honking, and people swerving to get in the way as I lane split (by the way I am in CA, and lane split more conservatively then these guidelines. I try not to be rude about it), certainly does not pertain to the driver being concerned about my safety. I believe that the safety argument is a front for other prejudices.

  • RoyEMunson

    The biggest safety concern for lane splitters are the cagers that oppose it under the guise of… safety.

  • Phenix_Rider

    Lane splitting is decidedly not legal in PA or DE, but I’m not going to sit still on an interstate if I can help it. And then there are situations where a car will sit two car-lengths back from a light with no reason or traffic is backed up for a quarter mile because of a break-down in the middle of an intersection. I’m absolutely going to take advantage of that space. Would I split past a driver that is visibly erratic or moving faster than 35? No. I think the CHiPs guidance was right on the money.

  • Ulysses Araujo

    “I can’t really see a logical reason to be splitting lanes at 50mph or greater as that means traffic is moving along just fine.”

    It’s the difference between trying to convince the idiot/careless driver of a ton-plus kg vehicle who’s dangerously close to your rear to stay further away and effortlessly reaching a safe spot overtaking another car.

    I’d rather risk a side collision in overtaking while splitting instead of being rear-ended anytime. This kind of situation happens often when the rest of traffic is slowing but usually you’re over that speed when things are starting to slow down.

  • Bruce Steever

    I’ve seen Joe’s flawed math elsewhere, too.

    Jensen has the right of it, as most “professional” lane-splitters will attest to: The most important variable in the entire equation is the speed delta.

    This determines your reaction time, maneuvering options, everything.

  • Bruce Steever

    In SoCal, traffic “moving along fine” is going 80 mph.

    50 mph is crawling.

  • Bruce Steever

    Take it up with UC Berkeley, then.

  • Bruce Steever

    You’re missing out, and by opposing it, hurting other riders.

    You don’t want to do it, fine – but keep your ignorant mouth shut.

  • Citizens might complain about it being unfair, incorrectly I might add, but state DOTs and police groups are opposing lane-splitting bills on grounds of safety.

  • 50 mph, on a motorcycle ,on a freeway, feels so sllooooowwwwww…

    Like I said before, as a veteran lane-splitter, I’d rather split at 50 mph than 5 mph. Drivers at 50 mph aren’t looking to make quick and sudden lane changes. Meanwhile, drivers at 5 mph are four-wheeled psychopaths.

  • Nick Jihad

    I live in LA and split lanes on daily basis, and have done so for years. The keys to safety in my view:
    1. Stick to commuter hours when everyone knows where they are going.
    2. It’s best done while the sun is up, but keep in mind that drivers get a very poor view from their mirrors when the sun is low and behind them.
    3. Watch your speed relative to traffic, and be very cautious between lanes that are moving at different speeds.

    I ride with the hi-beam on to try to stand out, but I keep the stock exhaust, to be courteous to the people i’m passing.

  • Nick Jihad

    I think you are mistaken about there being no room to maneuver when between lanes. First, it’s very hard to rear end the vehicle in front of you, when there is no vehicle in front of you. Second, you can get on the brakes very hard, and not worry whether the driver behind you is paying attention.
    When a driver shifts lanes as you approach from behind, they are generally doing so because there is a gap in the other lane – you can turn into that gap to evade them. Now, if a driver tries to change and there is already a vehicle on the other side, so that you are caught between, that’s bad, but it’s also rare.

  • Greg Zuro

    No it does not.

    From the document: “The current data set cannot be used to compare the collision risks for lane-splitting or non-lane-splitting riders”

  • crshnbrn

    And drivers going 50 mph are less likely to open their car doors than those going 5 mph.

  • Mitchel Durnell

    Please don’t keep your high beam on*. It’s blinding and distracting, and actually makes it harder to tell which side of my car you’re coming up on. Yes, I’m a rider too, and commuted on a bike exclusively in LA from 2009-2011 (up and down the 405 no less)
    * High noon on cloudless days, and when the sun is setting behind you are good exceptions.

  • Jack Hammer

    He means during the day. Hi beam isn’t going to blind you when the sun’s out. Running your hi beam during the daylight hours is common safety practice.

  • Jack Hammer

    CHP has been on record supporting the practice.

  • CortexUK

    Er, I don’t think it’s safer. Simple concept.

    And from the report:

    “”The current data set cannot be used to compare the collision risks for lane-splitting or non-lane-splitting riders””


  • CortexUK

    Did I say I stop anyone or campaign against it? All you people shouting me down for daring to express an opinion you disagree with are protesting far too much….

  • CortexUK

    What a stupid, nasty comment. Go and sneer at someone else. By opposing it I hurt no-one. And if I can’t express an opinion, neither can you, you arrogant hypocrite.

    In my view, lane-splitting is not safe. By thinking that I hurt no-one.

    Now go and run your foul mouth at someone else you pathetic little person.

  • CortexUK

    “”The current data set cannot be used to compare the collision risks for lane-splitting or non-lane-splitting riders”

    From the report. Now shut your ignorant mouth (right?).

  • Bruce Steever

    Nasty? Sure. Because i care about this.

    Lane-splitting is the Better Way for riders. Opposing this is no different from letting air out of the tires of your fellow riders.

  • M. Ellis

    Whether you’re for or against lane splitting, why hasn’t someone commented on the impossible graphic at the beginning of the article? When have you ever seen that much space between cars in each of the lanes? What are they all driving, Miatas?! :-)
    Also the graphic has the rider riding right on the dashed line, which is bad in most instances due to the lane reflectors and the slick paint they often use for making the lines.
    Just wanted to lighten the discussion… Now carry on. :-)

  • Rob Alexander

    So don’t do it, that’s your choice… but don’t try to restrict my ability to make the choice for myself.

  • Rob Alexander

    Actually saying you “oppose it” does imply that….