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I often think that when exiting a jam (the point where cars begin to speed up) that the best thing one can do for everyone behind you is speed up as fast as you

I often think that when exiting a jam (the point where cars begin to speed up) that the best thing one can do for everyone behind you is speed up as fast as you can. I've never modeled it or anything, but does this seem true to the folks here commenting on HN?

jbay808 7y ago
Don't speed up faster than the person in front of you, or you might end up having to touch the brakes and create a new traffic wave that propagates backward again.
ds206 7y ago
If I can see the next section of stopped cars, I will slowly accelerate and time it so that by the time I reach them, I don't have to stop and can continue driving at a somewhat constant rate. I'm not sure speeding up as fast as you can helps because usually there is another jam around the corner.
btilly 7y ago
No. The barrier is the time it takes people to start to move, not how fast they do once they do move. Therefore start up immediately, but there is no point in zooming ahead. In fact it is counter-productive! What really matters is reducing how many cars are stopped. Once that gets to zero, the jam can evaporate. Therefore when you see a jam ahead, slow down. Create space. And then try to just barely not have to stop. And when you come away, if there is any sign of a second jam create space and do the same. The result is you save on brakes, create immediate frustration for any stupid drivers who happen to be behind you, and make life a lot better for cars 20+ behind you.
- lotsofpulp 7y ago
  It's impossible to do this as each and every car has different acceleration and deceleration. The stop and go flow is inevitable. Trying to keep your car rolling is good, especially for wear and tear, but leaving excess space in front is also bad due to increasing the length of the congestion behind. The only solution is for cars to enter the congestion at a lower rate than they exit the congestion.
  - btilly 7y ago
    We rarely accelerate/decelerate to the limit of the car, and therefore should choose. If just a few percent of drivers did as I suggest, stop and go disappears. In effect slowing in advance moves the congestion back earlier, reduces its size, and makes it easy to have it evaporate. The reason that traffic jams happen is that freely moving traffic carries more cars per minute than stop and go. So there is a traffic volume where there are two states - everyone moving or traffic jam. But when everyone is moving, even minor slowdowns can cascade and switch states. And once switched, it is impossible to fix until traffic volume dies down and the hard stops are eliminated. We can't easily fix traffic volume. But the strategy that I suggest eliminates hard stops without reducing cars per minute. And therefore causes the jams to go away faster.

jbay808 7y ago

Don't speed up faster than the person in front of you, or you might end up having to touch the brakes and create a new traffic wave that propagates backward again.

ds206 7y ago

If I can see the next section of stopped cars, I will slowly accelerate and time it so that by the time I reach them, I don't have to stop and can continue driving at a somewhat constant rate. I'm not sure speeding up as fast as you can helps because usually there is another jam around the corner.

btilly 7y ago

No. The barrier is the time it takes people to start to move, not how fast they do once they do move. Therefore start up immediately, but there is no point in zooming ahead. In fact it is counter-productive! What really matters is reducing how many cars are stopped. Once that gets to zero, the jam can evaporate. Therefore when you see a jam ahead, slow down. Create space. And then try to just barely not have to stop. And when you come away, if there is any sign of a second jam create space and do the same. The result is you save on brakes, create immediate frustration for any stupid drivers who happen to be behind you, and make life a lot better for cars 20+ behind you.

lotsofpulp 7y ago
It's impossible to do this as each and every car has different acceleration and deceleration. The stop and go flow is inevitable. Trying to keep your car rolling is good, especially for wear and tear, but leaving excess space in front is also bad due to increasing the length of the congestion behind. The only solution is for cars to enter the congestion at a lower rate than they exit the congestion.
- btilly 7y ago
  We rarely accelerate/decelerate to the limit of the car, and therefore should choose. If just a few percent of drivers did as I suggest, stop and go disappears. In effect slowing in advance moves the congestion back earlier, reduces its size, and makes it easy to have it evaporate. The reason that traffic jams happen is that freely moving traffic carries more cars per minute than stop and go. So there is a traffic volume where there are two states - everyone moving or traffic jam. But when everyone is moving, even minor slowdowns can cascade and switch states. And once switched, it is impossible to fix until traffic volume dies down and the hard stops are eliminated. We can't easily fix traffic volume. But the strategy that I suggest eliminates hard stops without reducing cars per minute. And therefore causes the jams to go away faster.