How do traffic jams on the freeway start?

Question

Rubbernecking? Too many cars on the freeway?

Answer 1

They start when the volume of cars entering the freeway approaches the saturation capacity, the maximum traffic the freeway can handle.  Usually that's around 1800 vehicles per hour per lane, when the average headway - the time separation between successive cars - is 2 seconds (3600 secs/hr divided by 2 secs).  This is for recurring congestion, one that happens everyday.

Traffic jams can also occur even during free-flow conditions when a disturbance is introduced in the traffic flow, e.g., someone suddenly changes lane, someone sneezes, drifts to another lane while on cell phone or applying makeup, tunes a guitar, etc.  

Non-recurring congestion can be caused by incidents (crashes), major events (games or concerts), construction or maintenance (lanes are closed), or police activity (mainline is slowed down or stopped).

Answer 2

Basically too many cars.  A road would be designed and for a certain number of cars.  A road can have a certain capacity based on the number of lanes and speed.  If something affects that (something interesting beside the road that people slow down for, or construction or and accident that closes a lane) you have less capacity and thus you get a backup.  I think I head a number once that said that it takes about the affects of an incident are felt for about 5 times the length of the incident.  This is because during rush hours the roads are nearly full and there is very little room for extra traffic.  

So after all this rambling, the roads are nearly full during rush hour and it is a balance.  If you mess up that balance, with accidents, near accidents, construction, something slowing traffic ect.  You get major delays.  (Often the delays are strictly due to the number of vehicles)

Answer 3

Accidents, objects in the road are the main reasons

Answer 4

construction,accidents,slow drivers

Answer 5

addicted-to-oil drivers cluttering the road. Time to buy a bike, you guys, think about the planet.

Answer 6

Some idiot in the front driving slowly or stupidly causing a tail back to the other side of the country...

Answer 7

Chain reactions, if someone slams on their brakes for some reason or another it can cause the person to slam on theirs, etc.. etc. Therefore if a person does this ten miles away if can cause a pileup pretty quickly.

Also construction is usually the main cause here. Accident too. Anywhere where traffic has to stop or switch lanes quickly cause this as well.

Answer 8

In most cases its the Doppler effect.  Idiots that don't know how to drive, brake for no reason on the highway, when letting off the gas is all that's needed.  This causes the person behind them to break a little, the next guy has to break a little more, and so on and so on until drivers in the back have to finally stop.  This is a typical occurrence on freeways in metropolitan areas.

Answer 9

lots of things, they are redesigning some highways because they've found that certain exits cause blockage. Like when there is an on ramp (onto the highway) and further down this on ramp is an off ramp in the same lane. So the cars getting on have to compete with the ones getting off and it is not very efficient, causing back ups in heavily traveled areas. There are a few styles of interchanges, the old style traffic circle, the clover and more, the newest being something about an overpass, forget the exact name.

Answer 10

Provided there is no accident, or any or blockage or road work being done, this is another explanation, the "accordion effect": Someone slows down/brakes, the person behind them has to slow down more because there is a delay/reaction time between when the first car brakes, and when the driver of the second realizes it and brakes. And the driver behind them (driver #3) has to brake even more. So it reverberates down through the line of cars, eventually causing standstills.

Answer 11

many things, like a car accedent, or some old person just stops for no reason. lmfao