I have been writing about lane splitting for years -- it's the 'killer app' for motorcycles on increasingly congested roads. While a few states have considered amending traffic laws to specifically allow motorcycles to 'filter' through slow moving cars, as of now only California lets motorcycles filter. In the rest of the world, it's de rigeur (literally, filtering is a riding skill you need to demonstrate to get your license in the UK.)
My feeling on this is that allowing lane splitting in more U.S. states will drive up motorcycle sales and encourage the use of motorcycles as primary vehicles. When we lane split, not only do we get where we're going faster and with lower carbon emissions -- but by taking a vehicle out of the traffic column, a lane splitting motorcycle also marginally speeds the entire traffic column. And if lane splitting is the factor that encourages a driver to become a rider, then at his destination (in many cases) he or she frees up a parking space, too. So cars spend less time circling the block looking for a spot. Again, reducing carbon emissions and saving time for everyone, not just motorcycles. And, if making lane splitting legal across the U.S. increased the number of motorcycles in daily use, all motorcyclists would be safer. Right now, one reason car drivers don't notice us is that they're not used to seeing us, so they don't anticipate our presence and 'watch for motorcycles.'
The argument against lane splitting is basically that the vast majority of car drivers think it's not a killer app, it's just lethally dangerous. Many U.S. motorcyclists (especially non-Californians) share this misconception. Lane splitting is not inherently more dangerous than riding in the traffic column. By that, I mean lane splitting in a responsible, skilled way -- I've seen plenty of dumbasses lane splitting at speeds that make it dangerous, but those guys ride stupidly when they're not lane splitting, too. If you're an idiot, it's not lane splitting that's dangerous, it's motorcycles period. (The one consolation, I suppose, is that idiot motorcyclists really only endanger themselves. I guess if they were in cars they'd be even more dangerous.)
Where was I? Oh yeah, lane splitting: is it the killer app for motorcycles, or just a killer?
My friends at Aerostich, who created 'Ride to Work Day' in the U.S., recently sent out an email with a link to a study by Steve Guderian (any relation to Heinz? I'm not sure...) that attempts to tease the risks of lane splitting out of existing traffic accident data. You can - and should - read Guderian's study here. I get the feeling that he had a bit of a pro-lane splitting ax to grind, but safety studies going back to the Hurt Report in the '70s have all suggested that the strategy is less risky than it looks to most car drivers.
Back in the day when I commuted between San Diego and Motorcyclist Magazine's offices in downtown L.A., I lane split for hundreds of miles a week, and developed a whole theory of doing so as safely as possible. Basically, lane splitting is not as a riding exercise -- can I fit my motorcycle through that gap? -- but an exercise in data processing. Riding between columns of traffic is, in this sense, like riding in traffic generally: The only safe speed is the speed at which you can see, process, and control for every visible risk. If you can't process the onrush of data at the speed you're traveling, you need to slow down, increase gaps and following distances, until you're back at information equilibrium.
I've long been planning to write about this at length, but last week, MCN (in the UK) posted this excellent guide to filtering - as they call it. If you live in California and want to be a good lane splitter -- or if you live in the rest of the U.S. and are forming an opinion about lane splitting, read MCN's guide to filtering here.