The Hidden Cause of Traffic Jams—and How to Solve Them

Some traffic jams seem to happen out of nowhere—it’s not rush hour, no construction, no accidents. These are called phantom traffic jams, generally caused by drivers tapping the brakes on and off. Could autonomous vehicles eliminate these traffic jams, and make our roads safer? Some researchers think so.

PRODUCTION CREDITS:
Digital Producers: Ana Aceves, Emily Zendt
Editing: Ana Aceves
Production Assistance: Shyla Duff, Christina Monnen

MEDIA CREDITS:
Archival: William Barbour, Storyblocks, Nagoya University, Vanderbilt University
Music: APM
SFX: luffy / FreeSound

Footage of the experiment with cars driving in a circle to dissipate phantom traffic jams from a work supported by the National Science Foundation project “Control of Vehicular Traffic Flow via Low Density Autonomous Vehicles” under awards CNS-1446435, 1446690, 1446702, 1446715, and the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) award number CID DE-EE0008872. Video footage by John de Dios and Alan Davis.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the U.S. Department of Energy or the United States Government.

© WGBH Educational Foundation 2022

[Knightmessenger]

Whever I run into these slowdowns for no reason, I try to not alter my speed as much as possible. I'd rather go 30mph constantly than aggressively switch between 45 and 15 at a moments notice.
So does that mean I'm driving right? Too bad you'll never get drivers to move in unison with each other.

[royalace]

I can tell you quite how often I see cars braking for absolutely no reason. Theres wide open space in front of them, no traffic lights and they still decided to brake

[nickiemcnichols]

The worst drivers are the ones that tailgate, blast from traffic light to light, pound the brakes and gas pedal. They tailgate, and are often very rude. If we all would slow down, stay back, we could save time and fuel, and maybe lives.
And speed limit signs don't mean that's the minimum legal speed!

[jeffmpvd]

Cars cars cars.. no matter how much we spend on roads and now matter how big we build the roads it will never be enough. When ever I ride my bike or take a train or bus to get somewhere I feel liberated and happy to not be in my car.

[mwarnas]

"Well thank goodness. We found a thing. All we have to do is get half a billion self-driving cars on the road. Now we don't have to consider building decent public transport."

[geraldgarcia]

It would work with regular cars if everyone drove the same speed and didn’t rubber neck. People are always the main contributing factor to every problem.

[mduvigneaud]

Um, I think the best way to reduce traffic is to have better public transportation like trains, trolleys and busses rather than having so many individual, single occupant cars. Just saying.

[patricialessard]

I have seen traffic jams by "rubber neckers". One time on Rt. 93 going from Massachusetts to New Hampshire. The north bound lane was going fine(I was traveling south). Then there was a car off the road and looking like people were checking their cargo. I noticed cars slowing down a little too see what was going on. They started to bunch up until a
couple of miles down, they came to a complete stop on all 4 lanes! This stopped the traffic almost too Boston . Just because some people were nosey at a car that had nothing wrong. I thought that was unbelievable!

[KateeAngel]

1. Get better transit.
2. Reduce the width of highways and other roads.
3. Make parking expensive in the city centre
The number of cars on the roads will be smaller = PROFIT

[starjunkie]

OR...we could implement more and better public transportation like the European model. Our Trans system is intentionally designed for people to buy a car to get anywhere. I call that your typically greedy American transportation system; for sure, backed by all auto companies

[Vector_Ze]

For we folks who share the road with other human operated vehicles, the answer was given in the first 60-seconds of the video; STOP TAILGATING!

[budlaumer]

Right. 100 years ago, traffic lights were going to cure congestion. Then, in 1939, freeways were identified as the answer. In the 1960s better freeways were the answer. Now, these cars are the answer. Spoiler alert, there will be more of this as long as we depend on POVs for mobility. Thousands of vehicles in every city will never be the answer.

[MelGibsonFan]

How to solve them… uh, mass transit? Lol. To be honest I’d prefer accesible mass transit as opposed to spending hours in traffic every week.

[ChrisG]

the hidden cause is following distance. we learned about that in driver's education. if you use your brake pedal outside of actually stopping then you aren't a good driver.

[johnnyswatts]

How about we reduce the number of cars on the road by building better mass transit?

[jezzarisky]

I heard about a car that pulls several other cars on a fixed path that for the passengers is autonomous. These cars are both capable of higher capacity, and less lanes are needed.

[wisdon]

I believed this was an informative video but it's only an advertisement for Tesla.
the better way to counter traffic jams is to use public transportation on rails

[JonnoPlays]

Slow people in the fast lane need to *MOVE OVER*

Remember to coast instead of break whenever you can. Letting off the gas will slow your vehicle quite a bit. If you're leaving proper space between your car and the car in front of you then you can usually coast to slow instead of breaking and still have plenty of room for safety.

[skateebee]

How about coasting slowly when people are doing the stop n go? Just give yourself a little distance. In a short time the stop n go clears up

[stevenpellegrino]

Driverless cars will not end traffic jams. But cause more traffic jams. Because people in cars would slow to see who is controlling. The driverless car. And then cause accidents. And if we had only driverless cars. What do you do. If someone attacked you. And you need to get away. You jump in the car. It only drives they speed limit. You'll be attacked in lower speed zones. And be shoot. And the who drives emergency vehicles. You house is on fire. But the fire truck has to drive with traffic. And if someone says make a program. So cars more aside for the emergency vehicles. Then what if I set 10 fires. All the near by stations set trucks to those fires. As they are busy. I set your house on fire. Because it's what I really wanted to burn. Driverless vehicles will never work 100%> you need people in them controlling the. Driverless cars will not stop deer from jumping in front of cars. It will not stop trees and things from falling to block the road. And if your good at hacking into computers. I'll hack your car and cause it to not start. Some many things you don't consider. As to why you couldn't do it 100% I could go on for years. With ways it's not going to work.