Memory of the road

During a drive to work this morning, I had an interesting realization. At several points along the way, I had to break sharply, to maintain distance in front of the car ahead.

Why were they braking?

Precisely the same reason I assume.

In all likelihood the real danger was long gone.

So long as the quantity of traffic stays at a sufficient level, such as on a highway like SR520; these artifacts can potentially last for hours.

The memory of the road.