"Recovering from Traffic Jams"

The frequency of traffic jams can be suppressed by introducing more autonomous cars.
It has been proven that autonomous cars are effective in traffic jams.→Cause of Traffic Jams and Solutions

However, preventing all traffic jams is almost impossible.
If there is even one non-autonomous driving car, that car may cause a traffic jam.
Also, if an accident happens or a broken car blocks the way, inevitably the cars will become stagnant and a traffic jam will occur.
It is very difficult to prevent all traffic jams.

So, can autonomous cars clear traffic jams?
Let's do an experiment and verify that.


To compare the movements of the autonomous cars and the non-autonomous cars in a traffic jam, and to test the effectiveness of automatic driving vehicles in eliminating traffic jams.

Things to Prepare

  • (1)Circuit course using a black circle
  • (2)Autonomous Mobility Robot with three types of Programs for Robot Running on a Circuit Course(Learn more at Introducing MindstormsIntroduction of robots

    The ultrasonic sensor was used to measure the distance between each robot, and the color sensor was used to recognize the line of the circuit course. The M motor was used to move the rudder to the left or right, and the L motor was used to move the robot back and forth. In the following flowcharts, the rudder was moved to the right when the rotation of the M motor was a negative value, and the rudder was moved to the left when the rotation of the M motor was a positive value.

    • A)Robot that keeps a low speed constantly.
    • B)Robot that gets faster or slower according to the distance between vehicles.
    • C)Robot that has the function of B and have the highest speed after a certain period of time
        (when the cars cooperate with each other).


  • (1) Insert one robot A running at low-speed into a file of Bs running along the black line, to cause a traffic jam.
     Then remove A and observe the movement of the formation.
  • (2) Insert one A running at low-speed into a file of Cs running along the black line.
     Then remove A and observe the movement of the row.
  • (3) Compare and verify the results of (1)(2).

Experiment and Verification

(1) When we inserted one A into the file of Bs, (when we inserted a car running at low-speed into the five of quick car), the distance between the cars narrowed significantly and the speed dropped, resulting in traffic congestion.
Even after removing the slow car, the speed / inter-vehicle distance remained low.

(2) Just as with (1), we caused a traffic jam. After having removed the slow car, the autonomous-cars accelerated at the same time, and the speed and inter-vehicle distance recovered.

(3) Let's compare the situation after the late car is removed.
In (2), the speed and inter-vehicle distance recovered more quickly than (1), as the autonomous cars accelerated at the same time after the slow car was removed.


From this, we have proven that automatic driving vehicles can eliminate traffic jams.

Automatic driving vehicles can recover speed and inter-vehicle distance by communicating with other vehicles, and therefore eliminating traffic jams.

Questions after doing this experiment

There were some points we couldn't verify in this experiment and also some problem that were unnoticed.

① First, we cannot verify.
○ Whether autonomous cars can eliminate traffic jams if non-autonomous cars exist in the file .

In this experiment, there was a difference in the condition before the traffic jam occurred and after the traffic jam occurred:There was a non-autonomous car before the traffic jam occurred but there wasn't one after that.
Therefore, it was impossible to verify whether autonomous cars could eliminate traffic jams in the situation where the autonomous cars and the non-autonomous cars were mixed.

② Next, we will explain our suggestion to make autonomous cars by means to eliminate traffic jams that we found during the experiment
○ In order to use autonomous cars to solve traffic jams, it is necessary for all autonomous cars to cooperate with the other cars even if they are made by different car companies.

In this experiment, traffic jams were eliminated by all the autonomous cars in the file communicating together to accelerate at the same time. This assumes that all autonomous cars can cooperate.
As we introduced "Autonomous Car Made by NISSAN", the information learned by each of the autonomous cars are supposed to be shared only by the same company's autonomous cars.
In order to make autonomous cars useful in eliminating traffic jams, it is necessary for all autonomous cars made by various companies to share the information and cooperate with each other.

What I noticed through this experiment

←BACK Experiment Related Topic:Introducing Mindstorms
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