There is no single definition of tailgaiting other than being able to not being able to stop at a reasonable distance. So it is impossible to declare what constitutes tailing, especially in the mixed case of human drivers and robot drivers (who have a reputation for nuisance braking).
Why, for example, do you think trainers post "Student Driver" stickers on their cars? It's because it signals the driver may be more unpredictable and people (rightly) tend to give them wide berth. You're essentially advocating that everyone treat everyone else (and every robot) as a student driver. That's fine for a dichotomous safety mindset, but other people would prefer to recognize the tradeoffs with that approach.
Or maybe you're just deliberately bent on misunderstanding my point, I can't read your mind :)
> There is no single definition of tailgaiting other than being able to not being able to stop at a reasonable distance. So it is impossible to declare what constitutes tailing, especially in the mixed case of human drivers and robot drivers (who have a reputation for nuisance braking).
What is this nonsense? The safe following distance is determined by how fast you can stop, not by who is driving the vehicle you are following.
> Why, for example, do you think trainers post "Student Driver" stickers on their cars? It's because it signals the driver may be more unpredictable.
No, it signals they have less experience and are more dangerous drivers. When it comes to driver predictability, student drivers tend to be far more predictable than the adult, overconfident drivers. I've never seen a student driver roaring past me in stopped traffic on a shoulder, or floor the gas to pass me through a light because they didn't want to turn in a turn only lane, or any of the other unpredictable things I see on a regular basis from experienced drivers.
> You're essentially advocating that everyone treat everyone else (and every robot) as a student driver. That's fine for a dichotomous safety mindset, but other people would prefer to recognize the tradeoffs with that approach.
I think that if more driver treated the people around them as student drivers, our roads would be a lot safer.
I know that if people followed at a safe distance then we would have fewer traffic jams.
Edit: You also seem stuck on the idea that Waymo unsafely unexpectedly brakes more often than human drivers, yet that isn't clear to me from the data we have. Indeed it seems like the opposite is true from the data.
>The safe following distance is determined by how fast you can stop, not by who is driving the vehicle you are following.
So when you're driving, do you somehow know the braking distance of every car and reaction time of every driver around you? You don't, and since their braking distance is needed to know your own braking requirements, you have to use heuristics. Maybe your heuristic is "assume everyone will cram on the brake, full tilt, at any time." But, that is not a pragmatic solution given our current infrastructure. We don't have the road capacity for everyone to drive that way. So we make tradeoffs. Part of that tradeoff means anticipating what other drivers will do and adjusting accordingly. Naturally, this will trade some safety for other things we value. That is the reality of the world we live in. You seem to be advocating for something else. The OP was that we might struggle to apply such heuristics without a theory of mind to guide us.
We probably just disagree on the student driver vs. overconfident drivers. I feel like I'm pretty good at anticipating aggressive drivers, and I fear them must less than the super-tentative driver that tends to put other people at risk. But unless you have data, we're just talking about subjective opinion here so it's not really worth delving into further.
>I think that if more driver treated the people around them as student drivers, our roads would be a lot safer.
Sure. But again, it doesn't really fit with the world we live in. Should we all, in general, drive more defensively? Sure. But I doubt our infrastructure will allow for 25+ car lengths between vehicles that the NHTSA recommends, so we're stuck making some tradeoffs.
I agree on the data point. I'm not making strong claims about safety. I'm making claims about uncertainty. One thing that is clear (and I've advocated elsewhere) is that we don't have good data (in part, because companies get to share only what they want in many cases), which makes uncertainty greater.
> We don't have the road capacity for everyone to drive that way. So we make tradeoffs. Part of that tradeoff means anticipating what other drivers will do and adjusting accordingly. Naturally, this will trade some safety for other things we value.
You keep making the same argument over and over even though I've repeatedly explained that it does not match our understanding of how traffic jams form. Traffic jams are caused by braking, especially hard braking. Tailgating increases the need to brake hard if the person in front of you brakes or someone needs to merge. Following closely does not increase throughout, it is simply bad driving with no upside.
> I'm pretty good at anticipating aggressive drivers, and I fear them must less than the super-tentative driver that tends to put other people at risk.
Wow, if you read the behavior I descrived as "agressive driving" then we have completely different standards. I was describing reckless driving that blatantly violates the rules of the road.
Stop using excuses for your bad behavior and you might even be able to become a better driver.
What behavior of my own have I stated? Or are you inferring unwarranted conclusions to make ad hominem arguements?
>Traffic jams are caused by braking
Guess what one of the main issues has been in AV...nuisance braking. So much so that they suppress safety-critical actions to avoid unwarranted braking.
I also think you're confusing the proximate causes of conjestion for the root causes. Traffic conjestion is a load sharing problem. Tailgating is, in part, a symptom of inadequate capacity. You are advocating a solution that exacerbates it by reducing carrying capacity.
To reiterate (yet again) we aren't in disagreement about whether slowing down, or increasing following distance, will increase safety. It will, but also, that's not the point I was making. I'm just saying that is a superficial understanding of the problem and you aren't accounting for the tradeoffs. Those tradeoffs are the reason your proposal misses its mark.
> Tailgating is, in part, a symptom of inadequate capacity. You are advocating a solution that exacerbates it by reducing carrying capacity.
Why are we still debating something that has been answered by science? Stop assuming your intuitions are correct and look at what the science actually says about how follow distances affect the maximum capacity of a road.
Has it been answered by science? Because some of the studies I've come across list "heavy traffic" as a cause of tailgating. I think you might be speaking with unwarranted confidence.
25+ car lengths between vehicles that the NHTSA recommends
Is this hyperbole? I tried to Google for it, but I could not. The best I could find was the three second rule. Some back-of-the-envelope calcs: Length of Honda Accord (according to Google): 192 inches. 75 miles per hour / 60 minutes per hour / 60 seconds per minute * 5280 feet per mile * 12 inches per foot * 3 seconds / 192 inches = 20.625 car lengths. Even three seconds isn't enough to reach your recommendation of 25+ car lengths.
The actual calculation involves how fast the vehicle you’re following can decelerate, and your reaction time.
You can (usually) follow a large semi a bit closer because its braking distance is longer than yours.
But because of reduced visibility you can end up with “revealed brake checkmate” where the semi swerves into the next lane because a vehicle is stopped in the lane, which you then need to swerve or hit.
That's ridiculous. There's nothing "unrealistic" about 4.5 seconds of stopping distance - how could there be, are you thinking that the highways physically wouldn't fit all the cars spaced at that length?
It's unrealistic if you expect the existing infrastructure to meet both that requirement, the capacity requirements, and the time requirements of people travelling. In the real-world, there are tradeoffs. People who don't understand that tend to have superficial understandings of the problem because their mental models show little nuance.
I’ve entirely lost any semblance of a point you might have had initially. You’re doubling down on a weak stance making hyperbolic claims like “our infrastructure can’t handle cars leaving a safe following distance”. What nonsense!
It’s more effective to let your initial point stand and let the discussion run its course. You’re working against yourself now.
The claim seems reasonable. Most of the time infrastructure is fine, but that 20% of the time between 4pm and 6pm when you are actually using it, it often is not.
More following distance => less throughput. There is already a math problem at play for how to get millions of single occupancy to and from a given location in a day. Which is to say, gridlock occurs today - it is a fact. Increasing following distance by 2 to 5x would potentially be quite bad for otherwise heavy but flowing traffic. Eg: NYC, it is known for good throughput. Light turns green, everyone picks up speed and keeps tight following distances. Anything less and that city would lock up more so than it already does.
Part of the issue is just complexity and variety. 2x following distances on most highways would likely be only a good thing. But in each and every circumstance, not necessarily good, perhaps disaster.
There is pretty well established modeling that demonstrates that the stop and go rhythm that arises from tight following distances leads to worse throughput. To avoid slinking, everyone needs to accelerate and decelerate at the same rate. A safe stopping distance is the only way build in the micro buffers needed to achieve relatively consistent speed at human scale, or without large scale traffic orchestration. The naïve takes just sound like armchair hand waving. I guess that’s what I’m responding to.
It does seem on the road that many people lose the ability to predict 30 seconds in the future. That car in front of you has 10 feet to move? GO GO GO! Wait, it only moved just 10 feet - BRAKE BRAKE BRAKE!
I think it can fun to be the driver that smooths out the shock waves, so I do largely agree with your point. Though, all things being equal, double following distance and that will double the length of a traffic jam. Longer traffic jams are more impactful - it takes longer to get through them & the longer traffic jam distance is more likely to cause back-ups on on-ramps and in turn to the surface streets leading to those on-ramps. Which is to say, a higher prevalence of grid-lock.
The AI crowd is right to say that with 100% AI cars, you can have smooth and fast traffic with impossibly tight following distances. I do believe you need some impractical necessities to accomplish that though.
You seem very combative and seemingly deliberately missed the connections in other sub-threads, so why don’t you tell me what point you think I’m making and I can tell you how it’s accurate.
I’m not combatting anything… I am just offering my perspective that I think your OP is stronger on its own. The sub-thread digressions betray your unfamiliarity with the topic and your narcissistic nature rather than reinforce your OP. Take it or leave it, it’s just an internet opinion.
If you can't relay someone's point as you understand it, there's little reason to weigh in, and even less for that person to try and clarify it. It comes across as a need to argue, rather than a desire to understand.
Why, for example, do you think trainers post "Student Driver" stickers on their cars? It's because it signals the driver may be more unpredictable and people (rightly) tend to give them wide berth. You're essentially advocating that everyone treat everyone else (and every robot) as a student driver. That's fine for a dichotomous safety mindset, but other people would prefer to recognize the tradeoffs with that approach.
Or maybe you're just deliberately bent on misunderstanding my point, I can't read your mind :)