What causes a traffic jam?

As a driver, one of the worst things you encounter is traffic, especially when traffic happens for seemingly no reason. One second you’re cruising along at the speed limit and the next you’re in bumper to bumper traffic. If there are no accidents or construction, why do traffic jams still occur?

The science behind a traffic jam

Delayed reactions, tunnel vision, and selfish drivers—combined with congested roadways—greatly contribute to traffic jams but it ultimately boils down to physics. For example, let’s pretend that driver A is anxious to pass the slow driver in front of him. Driver A abruptly shifts into the left lane in front of Driver B. Driver B, who is driving at 60mph, must slow down to 55mph to avoid hitting Driver A. Meanwhile, Driver C who is behind Driver B must also slow down to 50mph and the driver behind him to 45 mph and so on and so on.

The process repeats and the traffic in the lane slows down. Drivers in this lane become impatient and switch to the faster moving lane. In doing so, the drivers they cut in front of must slow down to avoid collision and the process is repeated. This domino effect eventually causes all lanes of traffic to slow, and assuming that the roads are congested, a traffic jam occurs.

Most traffic jams are ultimately the result of disrupted and inconsistent driving speeds. By merging on time, paying better attention, leaving enough space between cars, and driving the correct speed limit, traffic jams could be greatly reduced.

For a better visualization of this concept, check out the video below.