4 ms·

On my Honda if a car merges in front of me and is accelerating, it maintains its speed presumably on the assumption that the separation will continue to increas

On my Honda if a car merges in front of me and is accelerating, it maintains its speed presumably on the assumption that the separation will continue to increase. If a car merges in front and is slower than me, i.e. separation is decreasing, it will brake in an attempt to maintain the set following distance. In practice it does leave a bit more following distance than most human drivers, but your worry of constantly getting cut off until you come to a stop in the road is not a real thing. This is partly because the car modifies the set following distance based on speed, so that the same setting is much closer at e.g. 5 mph than at 60.

lsaferite 3y ago
Also, at least on mine, it doesn't attempt to implement the full follow distance right away. Mine can tell a vehicle is accelerating away from me and won't slow down to fit the spacing on the expectation that the spacing will soon be achieved by the other vehicle. If the vehicle in front of me is going slower than my set speed and not accelerating, then it slowly will lag back to get the set follow distance. You do have to worry about aggressive cars that cut you off in heavy traffic as the vehicle will just let them and lag back, but I can at least adjust the follow distance to partially mitigate this situation.
sidewndr46 3y ago
OK, it's good to know that it won't stop. But if it slows automatically it will still result in the same thing. All the other drivers just continue to cut you off indefinitely.
- caconym_ 3y ago
  Actually, maybe I misunderstood you. I thought you were talking about adaptive cruise but you may have been talking about automatic emergency braking. Interpreting your original comment in that context: AEB only kicks in at a point where maximum braking will result in you barely not hitting something in front of you, or maybe even hitting it at a low speed. Modern cars can stop very fast indeed with maximum braking so in practice this threshold is never crossed under normal driving conditions unless the software returns a false positive. It's not about maintaining a safe following distance—it's about stopping the car at the extreme edge of the safety envelope, beyond which no manual or automatic intervention could prevent a violent crash. False positives do happen but I think they are very rare or practically nonexistent in good implementations. I've never had it happen with my Honda.
  - troutwine 3y ago
    Theoretically OP's concern is still possible with AEB but it would require non-trivial coordination between offensive drivers where each subsequent driver comes in at a lower speed than the previous, cuts OP's car off -- now slowed -- with the same distance as previous in order to force a standstill. It would be a neat stunt driving trick.

lsaferite 3y ago

Also, at least on mine, it doesn't attempt to implement the full follow distance right away. Mine can tell a vehicle is accelerating away from me and won't slow down to fit the spacing on the expectation that the spacing will soon be achieved by the other vehicle. If the vehicle in front of me is going slower than my set speed and not accelerating, then it slowly will lag back to get the set follow distance. You do have to worry about aggressive cars that cut you off in heavy traffic as the vehicle will just let them and lag back, but I can at least adjust the follow distance to partially mitigate this situation.

sidewndr46 3y ago

OK, it's good to know that it won't stop. But if it slows automatically it will still result in the same thing. All the other drivers just continue to cut you off indefinitely.

caconym_ 3y ago
Actually, maybe I misunderstood you. I thought you were talking about adaptive cruise but you may have been talking about automatic emergency braking. Interpreting your original comment in that context: AEB only kicks in at a point where maximum braking will result in you barely not hitting something in front of you, or maybe even hitting it at a low speed. Modern cars can stop very fast indeed with maximum braking so in practice this threshold is never crossed under normal driving conditions unless the software returns a false positive. It's not about maintaining a safe following distance—it's about stopping the car at the extreme edge of the safety envelope, beyond which no manual or automatic intervention could prevent a violent crash. False positives do happen but I think they are very rare or practically nonexistent in good implementations. I've never had it happen with my Honda.
- troutwine 3y ago
  Theoretically OP's concern is still possible with AEB but it would require non-trivial coordination between offensive drivers where each subsequent driver comes in at a lower speed than the previous, cuts OP's car off -- now slowed -- with the same distance as previous in order to force a standstill. It would be a neat stunt driving trick.