We’ve all been there. Driving in the fast lane only to encounter someone without a care in the world traveling a good 10-15mph slower than the surrounding traffic with nothing but open road in front of them. Sometimes its worse than a single car. Often, its people pulling large trailers, boats or RVs that have no business being anywhere near the left lane.

This is not just a complaint concerning those that camp out in the fast lane failing to keep up with the flow of faster traffic. Science has spoken, and yeah you’re not just being a jerk, if are one of these drivers you are actually making driving less safe for the rest of us. Research shows that many traffic jams result from a small number of slow cars holding up traffic creating a ripple effect as a buildup of cars cant pass as someone is driving slowly in the left lane.

Some drivers is the left lane believe, incorrectly, that they are the wall holding back other drivers that are driving well beyond the speed limit and therefore making things safer. Based on the actual research this belief is little more than a self-justification for, at its best annoying behavior and at its worst, a dangerous play that forces other drivers to make unnecessary lane changes, adding to the danger.

Driving slowly in the fast lane doesn't necessarily create danger, but it does create conditions that lead to more accidents. Lane changes account for as many as 10% of accidents on highways and that the strongest predictor of accidents isn't speeding but changes in speed among drivers, changes often created by slow drivers on the left. A car going 5 mph slower than surrounding traffic has a greater chance of causing an accident than one going 5 mph faster.

Germany’s Autobahn is a telling example. Fatality rates on the Autobahn, compared to US highways are lower even though speed limits are higher. Furthermore, lane discipline is more strict on the Autobahn forcing drivers to either travel the appropriate speed or move out of the way.

This is not an issue of simply being annoying to your fellow drivers. Many state’s laws, including California provide that drivers in the left lane must move over if driving slower than normal traffic, yet most do not. It's an issue that has only gotten worse as the roads become more congested and drivers find themselves needing to commute greater distances for work.

If you know of someone that engages in this reprehensible behavior have a talk with them about the danger that they are creating and that the left lane is for passing, not for camping.