The Double Yellow, and Cognitive Dissonance

John Allen

Safety Corner --The Double Yellow, and Cognitive Dissonance

A motorist is approaching a bicyclist from behind on a road with a double yellow centerline. The law says “don’t cross the double yellow.” But the motorist could pass safely only by putting at least part of the car on the left side of the double yellow.

What should they do? Should the bicyclist squeeze right as much as possible so the motorist can brush by with inches to spare, and not cross the centerline? Should the motorist brush by?

Well, one thing I can say in favor of common traffic engineering practice with centerlines is that it teaches people to think for themselves.  Almost every Massachusetts motorist has learned to take this law with a grain of salt, and cross the double yellow when necessary to pass a bicyclist safely.

Traffic engineering practice is based on the assumption that the vehicle being passed is going at nearly the posted speed limit. That requires long passing zones. If the vehicle being passed is a bicycle, or farm tractor, or Amish buggy, the passing distance is much shorter and the double yellow line leads to cognitive dissonance.

Given the law as is, what should we do?

As motorists? Well, crossing the centerline is the usual and generally accepted practice – but there is some small chance that it could get you in trouble. The likelihood of getting a traffic ticket and having to pay a fine is minuscule, because police also understand the problem with this law. But – be cautious, because it might be used against you if you do have a crash.

As bicyclists? This is one of the situations where it is most important to communicate with drivers, using lane position and hand signals. Indicate clearly when it is unsafe to pass, with your lane position and when necessary, an outstretched arm, palm of the hand facing the rear to communicate “Don’t!” But move right to facilitate passing when it is safe – the “control and release” technique. The driver behind you will be much more likely to cooperate if your actions make it clear that you are keeping that driver’s interests in mind.

This doesn’t only apply on roads with a double yellow line. Most lightly-traveled rural roads – the kind we most like because they are scenic, and quiet – have no centerline at all. And on blind right-hand curves, being farther to the left not only lets an approaching motorist behind me see me sooner, it lets me see farther ahead and move aside sooner. The motorist could appreciate this!

Several states including nearby Maine have amended their traffic laws to allow passing bicyclists when safe. The issue has been raised in Massachusetts, and CRW should support MassBike in its efforts to change the passing law.

For more background, you might go to



My experience is that drivers feel more comfortable passing me safely if I turn my head and glance back in their direction. It lets them know that I know that they're approaching. This practice works well enough that I do it even when I'm wearing a helmet with a mirror. This all assumes that first I've looked ahead to be sure I won't be inviting them into a dangerous situation.
John Allen's picture

Robert, good point. And it is also possible to let the driver know you are there -- and to indicate whether it is safe to pass, or not -- with hand signals.