4 ms·

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

by 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.
- branon 4y ago
  Sure, I'm fine with admitting that. It was an inevitable misunderstanding anyway because cars are different lengths so "car length" is largely meaningless. The Subaru's adaptive cruise control system treats car lengths as variable units based on speed. It's much more liberal than I made it sound in the original comment. It sounded reasonable when I wrote it, but infinite nuance strikes again I suppose.
  - foobazgt 4y ago
    Have an upvote for the adaptive cruise control comment. It's this way on the Tesla, too - follow distance is described as car lengths, but it's actually speed-parameterized follow distances in reality. Personally, I find it somewhat confusing, but people should probably be more aware that it's a thing and not necessarily someone mixing up terminology.
vel0city 4y ago
> One car length is way more than 15 feet to my mind, probably 40 feet or more Cars in your area are on average 40 feet long? A car length is about the length of an average car. Either way, with a 40 foot "car length", 1-2 car lengths is then ~80 feet. The above stopping distance chart puts a 40mph stopping distance with reaction time at almost 140 feet. <80 feet away is driving way too close at 40mph! Especially for a car you know is doing a maneuver which could result in them braking suddenly such as turning into another field of traffic.
- branon 4y ago
  With the amount of semi-trucks in my area, actually yes, average length of vehicles you encounter on the road is probably close to that. I just used the term "car length" with entirely too much room for interpretation and am now getting torn apart for it, my mistake. I swear I'm not tailgating people LOL
  - vel0city 4y ago
    > I swear I'm not tailgating people LOL If you're going 40mph and approaching nearly stopped cars at <80 feet, you're absolutely tailgating people and creating extremely risky situations. Don't get me wrong, I've had my emergency braking trigger for similar circumstances of someone turning into a parking lot off a feeder of a highway. But I don't blame my equipment, I acknowledge I'm not a perfect driver. The car knew it could have been quite a challenge to stop in time and so it took action. The better action would have been for me to be going slower and approach that situation with less speed, not to just blame the car for being cautious and forcing realistic safety margins.
    - branon 4y ago
      Nobody's approaching nearly stopped cars, I think you have misunderstood some other facet of my post. I sometimes approach _decelerating_ vehicles, _while I am also decelerating_
      - 4y ago
emptybits 4y ago
> One car length is way more than 15 feet to my mind, probably 40 feet or more depending on speed. A car length is, literally, the length of a car. It does not vary with speed. Exception: https://en.wikipedia.org/wiki/Length_contraction https://en.wikipedia.org/wiki/Length_contraction (coming soon in a software update to a Tesla near you)
- branon 4y ago
  Sure, but saying this is meaningless when we're actually talking about follow distance. Cars are different lengths. To me, a car length should simply mean the minimum safe _length_ at which to follow the car in front of you.
  - berberous 4y ago
    This would lose all communicative benefits. Teaching a young inexperienced driver “just always keep one car length” where one = safe, is meaningless. I don’t know you, but I believe a majority of people underestimate safe stopping distance. That’s why the webpage I posted, which is one of many similar ones, exist. That’s also in part why there are so many accidents. People are also bad at estimating feet, so telling someone keep 80 feet is also not helpful. But people are pretty good at estimating how many cars can fit between them and the next car. So telling someone, hey, you are tailgating that guy and only one car could fit in front of you, but you need 10 car lengths to be safe, has a lot more communicative power.
    - branon 4y ago
      > Teaching a young inexperienced driver “just always keep one car length” where one = safe, is meaningless. Not if taught correctly, which I think it's important to note that we can't really do via textual communication. In the driver's seat, during a driver's education course, you might learn that a car length is the length of an average car, but you also learn how to count the seconds of stopping distance you have in front of you. In addition, you learn that weather, traffic, and other factors can affect stopping power/distance, the point being that the whole system is incredibly dynamic and variable. One can't reduce a dynamic traffic situation down to "X car lengths = safe." Similarly, saying "1 car length = a safe distance" doesn't really help either. The idea is to teach people what "safety" actually looks like. How it's referred to is secondary. The proof is in how badly I was misunderstood when I said 1-2 car lengths. I _know_ I'm keeping enough distance, because I know how to judge a safe traffic situation. I don't really care what a car length is or isn't, it's fairly irrelevant because safety is a much bigger picture than units of measurement.

by branon 4y ago

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.

branon 4y ago
Sure, I'm fine with admitting that. It was an inevitable misunderstanding anyway because cars are different lengths so "car length" is largely meaningless. The Subaru's adaptive cruise control system treats car lengths as variable units based on speed. It's much more liberal than I made it sound in the original comment. It sounded reasonable when I wrote it, but infinite nuance strikes again I suppose.
- foobazgt 4y ago
  Have an upvote for the adaptive cruise control comment. It's this way on the Tesla, too - follow distance is described as car lengths, but it's actually speed-parameterized follow distances in reality. Personally, I find it somewhat confusing, but people should probably be more aware that it's a thing and not necessarily someone mixing up terminology.

vel0city 4y ago

> One car length is way more than 15 feet to my mind, probably 40 feet or more Cars in your area are on average 40 feet long? A car length is about the length of an average car. Either way, with a 40 foot "car length", 1-2 car lengths is then ~80 feet. The above stopping distance chart puts a 40mph stopping distance with reaction time at almost 140 feet. <80 feet away is driving way too close at 40mph! Especially for a car you know is doing a maneuver which could result in them braking suddenly such as turning into another field of traffic.

branon 4y ago
With the amount of semi-trucks in my area, actually yes, average length of vehicles you encounter on the road is probably close to that. I just used the term "car length" with entirely too much room for interpretation and am now getting torn apart for it, my mistake. I swear I'm not tailgating people LOL
- vel0city 4y ago
  > I swear I'm not tailgating people LOL If you're going 40mph and approaching nearly stopped cars at <80 feet, you're absolutely tailgating people and creating extremely risky situations. Don't get me wrong, I've had my emergency braking trigger for similar circumstances of someone turning into a parking lot off a feeder of a highway. But I don't blame my equipment, I acknowledge I'm not a perfect driver. The car knew it could have been quite a challenge to stop in time and so it took action. The better action would have been for me to be going slower and approach that situation with less speed, not to just blame the car for being cautious and forcing realistic safety margins.
  - branon 4y ago
    Nobody's approaching nearly stopped cars, I think you have misunderstood some other facet of my post. I sometimes approach _decelerating_ vehicles, _while I am also decelerating_
    - 4y ago

emptybits 4y ago

> One car length is way more than 15 feet to my mind, probably 40 feet or more depending on speed. A car length is, literally, the length of a car. It does not vary with speed. Exception: https://en.wikipedia.org/wiki/Length_contraction https://en.wikipedia.org/wiki/Length_contraction (coming soon in a software update to a Tesla near you)

branon 4y ago
Sure, but saying this is meaningless when we're actually talking about follow distance. Cars are different lengths. To me, a car length should simply mean the minimum safe _length_ at which to follow the car in front of you.
- berberous 4y ago
  This would lose all communicative benefits. Teaching a young inexperienced driver “just always keep one car length” where one = safe, is meaningless. I don’t know you, but I believe a majority of people underestimate safe stopping distance. That’s why the webpage I posted, which is one of many similar ones, exist. That’s also in part why there are so many accidents. People are also bad at estimating feet, so telling someone keep 80 feet is also not helpful. But people are pretty good at estimating how many cars can fit between them and the next car. So telling someone, hey, you are tailgating that guy and only one car could fit in front of you, but you need 10 car lengths to be safe, has a lot more communicative power.
  - branon 4y ago
    > Teaching a young inexperienced driver “just always keep one car length” where one = safe, is meaningless. Not if taught correctly, which I think it's important to note that we can't really do via textual communication. In the driver's seat, during a driver's education course, you might learn that a car length is the length of an average car, but you also learn how to count the seconds of stopping distance you have in front of you. In addition, you learn that weather, traffic, and other factors can affect stopping power/distance, the point being that the whole system is incredibly dynamic and variable. One can't reduce a dynamic traffic situation down to "X car lengths = safe." Similarly, saying "1 car length = a safe distance" doesn't really help either. The idea is to teach people what "safety" actually looks like. How it's referred to is secondary. The proof is in how badly I was misunderstood when I said 1-2 car lengths. I _know_ I'm keeping enough distance, because I know how to judge a safe traffic situation. I don't really care what a car length is or isn't, it's fairly irrelevant because safety is a much bigger picture than units of measurement.