4 ms·

That was just one example. I've clarified my original comment, previously I was using the term "car length" in a way that did not make sense to others. I should

by branon 4y ago

That was just one example. I've clarified my original comment, previously I was using the term "car length" in a way that did not make sense to others. I should have said "seconds of follow distance" All of this is infinitely nuanced anyway. There might not be a side street. It can happen on the highway too when cars switch lanes to exit. And it's not like it happens every day, it's fairly rare, I just have yet to actually _need_ the car to do it, by a fairly wide margin. 1-2 car lengths (not in literal units of 15-feet each, I mean one or two _seconds_ of follow distance minimum after accounting for speed/traffic/weather) going the speed limit with my foot off the gas and over the brake, paying attention ready to slow down fast in case of a contingency feels very safe to me. Again, pretty nuanced, this only lasts for a handful of seconds while the lead car completes their maneuver. The salient point is that I already do what the machine tries to replicate, I don't need my maneuver clobbered by another system.

DiggyJohnson 4y ago
I’m not comfortable at all claiming that you’re a bad driver in general, like the GP proposes, and maybe I’m taking your unit of measurement too literally, but I don’t think 1-2 car lengths is a reasonable follow distance in almost any circumstances above 45mph, two lengths is kinda the minimum to not bother the person in front of you. Again, I’m making a very general statement, that might not apply to the situations you’re describing. And I’m a young guy that is working on being a more conservative driver myself - so I’m chuckling to myself just at the idea of me taking this side of the discussion.
- branon 4y ago
  This is an interesting point. The Subaru's adaptive cruise control system treats a "car length" as a fairly large unit of measurement. One car length seems to be the literal length of the vehicle, plus some reasonable amount of buffer on both ends. Probably twice as large as the vehicle itself. And the faster you're going, the larger a single car length becomes. Infinite nuance :P But in general, very good commentary on systems that provide useful feedback for the human operator versus ones that don't. ACC makes it clear what a car length should be, and if you're paying attention you can gauge how much more space it leaves when you're moving fast. So that's what I go by.
  - indymike 4y ago
    The Subaru uses two seconds per tick mark on the adaptive cruise display, so the distance changes as you go faster. At slow speeds, it's roughly exact car lengths, and at 65MPH it's considerably further.
  - DiggyJohnson 4y ago
    Fwiw, it’s interesting to me that the unit of a “car length” would not refer to a literal car length (14-17 ft or so).
berberous 4y ago
Have you ever looked up stopping distances? https://www.automotive-fleet.com/driver-care/239402/driver-care-know-your-stopping-distance https://www.automotive-fleet.com/driver-care/239402/driver-c... I don’t know how accurate the above is, but it suggest that the stopping distance at 40mph is 5-9 car lengths, so I have to agree with the above poster that if you are routinely leaving one car length and your car system is freaking out, you are probably driving unsafely. Keep in my that statistically this could work out for you fine for 20+ years before one day you get into accident, and presumably blaming the driver who suddenly stopped mid turn. Check out watchpeopledie or idiotsincars for plenty of videos of what could go wrong. I recall one video of exactly this issue — an idiot SUV stopped mid turn in the middle of a lane, clearly a bad driver. And then another driver t-boned her because he didn’t have enough distance to stop, also cleary partially at fault IMO. I know people with lifelong pain from minor auto accidents. Don’t have that be you, or cause that for someone else. What do you lose by keeping some more space between you and the next car?
- branon 4y ago
  One car length is way more than 15 feet to my mind, probably 40 feet or more depending on speed. See my other comments about how nuanced this entire dialog will inevitably be. Don't you think it's more reasonable to assume we have different definitions of a car length? Perhaps I've used the term in a grossly incorrect manner. "One car length" to me equals "one unit of minimum safe distance taking into account road conditions, traffic conditions, and speed" Not just 15 feet, that'd be insane!
  - tshaddox 4y ago
    I think you are confused (either that or I am!). I’m pretty sure a car length is literally the length of a car, which for a Crosstrek is around 15 feet. Given this confusion, it does seem like it explains the root of the disagreement here, but that said, I don’t think it’s unreasonable for people reading your comment to assume that when you said “car length” you meant the length of a car.
  - VBprogrammer 4y ago
    You could just admit that you used the wrong term? One car length = the length of a car.
tshaddox 4y ago
2 car lengths? So like, 250 milliseconds at 40 miles per hour?

by branon 4y ago

DiggyJohnson 4y ago

I’m not comfortable at all claiming that you’re a bad driver in general, like the GP proposes, and maybe I’m taking your unit of measurement too literally, but I don’t think 1-2 car lengths is a reasonable follow distance in almost any circumstances above 45mph, two lengths is kinda the minimum to not bother the person in front of you. Again, I’m making a very general statement, that might not apply to the situations you’re describing. And I’m a young guy that is working on being a more conservative driver myself - so I’m chuckling to myself just at the idea of me taking this side of the discussion.

branon 4y ago
This is an interesting point. The Subaru's adaptive cruise control system treats a "car length" as a fairly large unit of measurement. One car length seems to be the literal length of the vehicle, plus some reasonable amount of buffer on both ends. Probably twice as large as the vehicle itself. And the faster you're going, the larger a single car length becomes. Infinite nuance :P But in general, very good commentary on systems that provide useful feedback for the human operator versus ones that don't. ACC makes it clear what a car length should be, and if you're paying attention you can gauge how much more space it leaves when you're moving fast. So that's what I go by.
- indymike 4y ago
  The Subaru uses two seconds per tick mark on the adaptive cruise display, so the distance changes as you go faster. At slow speeds, it's roughly exact car lengths, and at 65MPH it's considerably further.
- DiggyJohnson 4y ago
  Fwiw, it’s interesting to me that the unit of a “car length” would not refer to a literal car length (14-17 ft or so).

berberous 4y ago

Have you ever looked up stopping distances? https://www.automotive-fleet.com/driver-care/239402/driver-care-know-your-stopping-distance https://www.automotive-fleet.com/driver-care/239402/driver-c... I don’t know how accurate the above is, but it suggest that the stopping distance at 40mph is 5-9 car lengths, so I have to agree with the above poster that if you are routinely leaving one car length and your car system is freaking out, you are probably driving unsafely. Keep in my that statistically this could work out for you fine for 20+ years before one day you get into accident, and presumably blaming the driver who suddenly stopped mid turn. Check out watchpeopledie or idiotsincars for plenty of videos of what could go wrong. I recall one video of exactly this issue — an idiot SUV stopped mid turn in the middle of a lane, clearly a bad driver. And then another driver t-boned her because he didn’t have enough distance to stop, also cleary partially at fault IMO. I know people with lifelong pain from minor auto accidents. Don’t have that be you, or cause that for someone else. What do you lose by keeping some more space between you and the next car?

branon 4y ago
One car length is way more than 15 feet to my mind, probably 40 feet or more depending on speed. See my other comments about how nuanced this entire dialog will inevitably be. Don't you think it's more reasonable to assume we have different definitions of a car length? Perhaps I've used the term in a grossly incorrect manner. "One car length" to me equals "one unit of minimum safe distance taking into account road conditions, traffic conditions, and speed" Not just 15 feet, that'd be insane!
- tshaddox 4y ago
  I think you are confused (either that or I am!). I’m pretty sure a car length is literally the length of a car, which for a Crosstrek is around 15 feet. Given this confusion, it does seem like it explains the root of the disagreement here, but that said, I don’t think it’s unreasonable for people reading your comment to assume that when you said “car length” you meant the length of a car.
- VBprogrammer 4y ago
  You could just admit that you used the wrong term? One car length = the length of a car.

tshaddox 4y ago

2 car lengths? So like, 250 milliseconds at 40 miles per hour?