What Is Lane Filtering?

"Lane Filtering" is the process of motorcycles riding between lanes of slow, or stationary traffic, and "filtering" forward.  It is not only legal, but expected in most of the world.  While not codified into law, it is  accepted in California.  Although it is up to the individual police officer to decide whether you are doing it 'safely' or not.

It has been shown in several studies done in Europe (where it is considered to be the only way to get around on a motorcycle in a city), that lane filtering not only lowers the travel time of motorcyclists in congested traffic, it also helps to ease that congestion.  When motorcycles aren't taking up space sitting statically in traffic that could be filled by a larger vehicle, traffic congestion has been shown to be less.  It has also been shown to be safer for the motorcyclist.  According to the MAIDS (Motorcycle Accident In-Depth Study) of 2009, lane filtering is six times safer for a motorcyclists than sitting  in traffic.  Also according to MAIDS, only 0.45% (that's right, less that one-half of one percent) of motorcycle accidents in Europe were related to lane filtering maneuvers.

A recent study for the US Dept. of Transportation compared; California, Texas, and Florida motorcycling accident rates.  With similar year 'round riding seasons, similar riding demographics, California still showed a 20% lower rate of fatalities due to rear end collisions.  California is the only state in the US to currently allow lane filtering.  With riders not having to sit stalled in traffic, and open to being rear ended by inattentive drivers, California's motorcycling community is allowed a significant safety margin by being able to filter through traffic.

Even a 2010 report by the Oregon D.O.T. had good things to say about lane filtering.  Although some of the conclusions were obviously made by someone who isn't very familiar with most modern motorcycles, it still shows the positive benefits of lane sharing.

Some of the benefits mentioned in the Oregon D.O.T. report include the following:
1. "In addition to contributing to congestion reduction by the capacity/size differential, motorcycles help to free additional space when lane-sharing. When motorcycles move from the travel lane to the center line space is created."
2. "One of the early benefits recognized for lane-sharing was to help keep air-cooled motorcycle engines from overheating.  When kept in motion, the engines are cooled by the air flowing over the fins, but when stopped there is no mechanism for cooling."
3. "Conversely to safety concerns with lane-sharing, a potential safety benefit is increased visibility for the motorcyclist. Splitting lanes allows the motorcyclist to see what the traffic is doing ahead and be able to proactively maneuver."

One of the main concerns about lane sharing, seems not to be about the motorcyclist being able to ease traffic by filtering through traffic, but to be about automobile drivers becoming startled by a motorcycle passing between lanes and then moving the car resulting in a possible sideswipe and turn-into-path accident.  So in other words, if a automobile driver isn't paying attention (like that EVER happens) and is startled by a motorcycle passing between lanes, they may suddenly turn their car to block the path the motorcycle just took.  This is my personal opinion here; and not backed up by any statistics or studies, just my many years of experience operating many different types of vehicles on the roadways.  But it has been my experience that if a driver is startled by a motorcycle moving between lanes at no more than 10 mph faster than traffic, that same driver would be "startled" any vehicle coming up alongside them.  It means they aren't checking their mirrors, or they aren't checking them often enough.  Or, they are pissed off because the motorcyclist is "cutting" past the line, and not "waiting his turn".  A little road rage rises up, and the driver moves to block any other motorcycles from passing him...or they pull the old open the door trick.  Which by itself is illegal here in Washington.  At the same time, if a bike is blasting between lanes at a high rate of speed, they aren't acting in a "safe and prudent manner" anyway and are asking for trouble.

Well now you know a little bit about lane filtering.  If you think the idea of; better commute times through congested traffic, lower possibility of being rear-ended, and actually easing traffic is a good idea, then you like the idea of lane filtering.  If that's the case, and you live in Washington state, let your legislator know how you feel.

Catch you on the road sometime...