What Causes Traffic Jams?

We’ve all been stuck in them before, but why the difference? Sometimes the traffic just flows by with no problems. But sometimes cars are lined up for miles. And this can be at the same worksite depending on the day, or even hour! Safety systems So why the huge variance?

There are 2 prevailing theories as to how to mitigate the effects of a traffic jam.

  • Use All lanes as long as possible
  • Get in line early on and be prepared to file through the workzone

Both of which overlook the underlying causes of traffic jams, and truly just determine the location of the jam.

The two true causes of traffic jams are mistakes merging and inattentiveness. 

Mistakes Merging

Just about everyone would agree, merging is one of the biggest challenges for drivers today. Yet there are very few who would categorize themselves as a part of the problem, Myself included. Which is what makes it so tricky, Merging requires the coordinated efforts of all involved to keep traffic moving. The two variables that are of the most importance in merging are Speed, and Space. 


Speed is the primary responsibility of the one merging, they are responsible for matching the flow of traffic if at all possible. Failure to do so results in a slowdown of traffic following and resultant decrease in space. This makes all following merges more difficult and dangerous to execute. Subsequently forcing further slowdowns to compensate.


Space is the responsibility of the driver in the lane being merged into. Space refers to the distance between the front bumper of their car, and the car in front of them. The driver must maintain a minimum of at least 3 seconds worth of space between the cars at any given speed, with that distance increasing as speed increases. For example, if the car in front of you were to pass a mile marker, you should be able to count 3 seconds before that same mile marker passes your front bumper. Maintaining this distance gives merging vehicles room to merge without forcing drivers to slow or stop to make room for them.

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