Book 25, Question 35 · Video
Why do traffic jams sometimes happen even without an accident?
A jam can start when one driver taps the brakes. The next driver brakes a little harder, and the next even harder. The slowdown moves backward along the road as a wave, even after the first driver has sped up again. Scientists have seen this wave in experiments with cars on a circular track. Leaving space and driving smoothly can help.
Read the full answer →Watch on YouTubeSee the series on Amazon
What Crafty Clover says in this video
Intro
Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do traffic jams sometimes happen even without an accident?
The Big Idea
Sometimes traffic stops, and there is no accident at all! Why does that happen? It is a wave of brakes!
One Tap
Step one: One Tap. A jam can start when one driver taps the brakes. The next driver brakes a little harder, and the next even harder.
The Wave
Step two: The Wave. The slowdown moves backward along the road as a wave. It keeps going even after the first driver has sped up again.
Smooth Driving
Step three: Smooth Driving. Scientists have seen this wave in experiments with cars on a circular track. Leaving space and driving smoothly can help.
A Closer Look
Let's take a closer look! One driver taps the brakes. The next brakes harder. The wave grows. It moves backward.
Quick Facts
Quick facts! These jams are called phantom jams. Scientists recreated phantom jams on a circular test track. Space between cars helps. Smooth speeds help flow.
Think Like a Scientist
Now, think like a scientist! Line up with friends and walk in a row. Have the first person stop briefly, then go again. Watch how the pause travels backward. Try again with more space between people. What changed?
Outro
Traffic jams can happen without accidents when one driver taps the brakes and each driver behind brakes harder, sending a slowdown wave backward. Leaving space helps. Science is amazing! Keep asking questions! The more you look around, the more wonders you will find, so keep your eyes open! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!