Infographic: Why Do Highway Traffic Slowdowns Happen? | W+A

The Summer Driving Season: Why Do Those Slowdowns Happen??!!

We’ve all been through it. Your summer vacation has started, you’re cruising down the highway to your sunny destination, and then it happens … the dreaded slowdown. For no apparent reason. And just a few short years ago, before the Google Maps app and Waze, you had no idea how long the backup was. At least we have that.

Our transportation planning team works all over the country, but with a base of traffic engineers in the Washington DC region, we experience these aggravating slowdowns just like everybody else.

An Aggravating Traffic Chain Reaction

infographic - why does highway freeway traffic come to a stop?It might be some consolation to know why these aggravations occur. The folks at have come up with a cool yet informative infographic to show why these slowdowns can happen – scroll down or click the thumbnail for the infographic. That is – slowdowns that aren’t necessarily the result of a road-clogging accident or construction.

In essence, it’s just a chain reaction of slowdowns – reverse accelerations. The first driver puts on the brakes, the second slows down even more, and so on, until you’ve come to a near stop. Arggh. What’s truly aggravating is that the slowdowns themselves can occasionally cause an accident.

This happens despite the best of intentions, and the best of civil engineering methods performed by those licensed as a Professional Engineer (PE). How does one become a PE? First, engineers must complete a four-year college degree, and then work under a Professional Engineer for at least four years. In addition, hopeful PEs must pass two intensive competency exams and earn a license from their state’s licensure board.

Retention of licenses only happens if PEs regularly maintain and update their skills throughout their careers. Despite a host of engineering issues and disciplines that go into constructing and maintaining a modern highway – interchange ramp design, collector-distributor roads, multi-lane roadway transitions, HOV lanes, etc. – the slowdowns happen. So no matter how fast, or slow, you get to your destination, the W+A team wishes you speedy – but safe – travels on your vacation.

infographic - why does highway freeway traffic come to a stop?