Featured Phantom Traffic Jams, and a new type of Adaptive Cruise Control

The key word in the research is everybody

 

"Berthold says Toyota funded his research and might be implementing this new two-way model of adaptive cruise control in the future.
However, to see significant changes in traffic times, there needs to be wide adoption and that won't happen instantaneously"

Except this won't stop impatient drivers from turning off or just not using the system. It would also take decades to get close to 100% implementation.

 

Hmm, maybe. I think complete autonomous driving is the only real solution.

 

With enforced autonomous only roads, maybe.

 

My thoughts on our local freeway 880 between Oakland and San Jose and its traffic (jams):

Traffic speed ALWAYS changes even a little bit in every lane even when traffic flowing freely. It seems pretty much everyone does NOT use even DUMB (non-adaptive) cruise control on urban freeways. And using dumb cruise control amounts to hitting + button, - button, + button again and again. Hardly worth it.

Some people leave LARGE GAPS (6, 10, 15 car lengths) to the car ahead at highway speeds in heavy traffic. This wastes space on freeway, slows traffic, causes some to get frustrated and drive around, jockey for position. It's better to 'go with the flow' on freeway, but COMMON SENSE in this not used by everyone.

Commuter traffic is so bad around here, stop and go gridlock is daily occurence. It's a hassle, requires constant attention to fit in, not hit anyone. Really good full speed cruise control would be much less stressful. Who knows how many would use it even if it worked well in their car. My next new car will have full speed cruise control that works very well even in stop and go traffic.

 

too many cars, too little time...

 

LOL My wife noticed after we changed the oil on our Corolla that it has only gone 2K miles in the past year.

 

My mom only has averaged about 2K miles a year since retirement on her car. At that pace there is no reason to replace her avalon until she stops driving. I put synthetic oil in it the last time I visited, figuring that will be good for 2 years with how little she drives.

Back to the point, there are a lot of cars that will not be replaced for at least 15 years. Maybe in some cities you want to incentives people to get new vehicles so they can have adaptive cruise control with accident avoidance when the technology is cheaper (maybe 5 years from now), but just given economics I don't expect it will have a major impact on traffic for at least 2 decades without strong incentives to get old vehicles off the road. California is one of the states with the worst traffic, but its registration fees based on cars value may make getting a large enough population of cars with these features in the fleet even slower than other states.

 

And I'd guess she drives very short distances. Long intervals between drives, short drives...both are reasons I'd be changing the oil twice as often and not twice as long. Typically, when tested, a car driven with those patterns shows lots of condensation/water in the oil. Yea every 6 months. I drive my Prius about 8k and the wife her Avalon maybe the same per year. 5k oil changes for us.

 

Common sense is what I use all the time, never what anyone else does!

Toyota UK specify service with oil change at 10,000 miles or 12 months, whichever comes sooner.

 

Only someone habituated to extreme tailgating could portray 6 or 10 car lengths at highway speed as 'LARGE'.

At 60 mph, the minimum legal spacing in my state is 120 feet, which is 8 Prius car lengths. The commonly taught Two Second Rule comes out as 176 feet, which is well over 11 Prius lengths. At higher speeds, the number of required car lengths increased proportionately.

Yes, I know that urban traffic very commonly packs in significantly closer. But no one should portray the above spacings as excessive or too large.

 

Point taken. # seconds apart better way to be safe. Sometimes I see freeway drivers mph leave 10 or more seconds between them and next car in front. Breaks the flow of traffic: Next I see people get frustrated behind that person, people start changing lanes, going around.

Far fewer cars could fit on freeway if everyone insisted on 10 seconds to the next car. I leave about 3 seconds at 65 mph

 

Seconds are generally a better spacing rule, because it automatically adjusts for differing speeds, and because people are generally more rotten at estimating distance than time.

Around here, 10 second car spacing usually qualifies as a virtually empty road with free-flowing traffic. (Though it also describes stop-and-go with far more stop than go.) I'd say that average rush hour spacing is well under 2 seconds, and a great many vehicles using less than 1 second. And a non-negligible fraction are under a half second.

At 60 mph, 2 second spacing will carry about 1600 vehicles per lane per hour. (When figuring average vehicle length, don't forget the longer pickups and commercial trucks in the mix.) I don't believe roads in my area will handle much over 2000/lane/hour before the slightest disturbances create phantom stop-and-go traffic jams, sharply reducing lane throughput.

Aggressive tailgating driving cultures elsewhere seem to push that threshold somewhat higher. But they also experience far larger mass pile-ups. I seem to remember yesterday's mass chain reaction crash somewhere as involving 62 vehicles, though only 1 dead.

That is actually 19 car lengths.
(95 feet/second * 3 seconds)/(15 feet/carlength) = 19.

 

IIRC, defensive driving courses recommend 2 seconds between cars.