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Comment by felipemnoa | Hacker News Reader

>>I've nearly rear-ended a couple myself

How is this possible? I think you may be driving too close to cars.

:-) You haven't driven around SF much perhaps? But notice he said "almost" not "did" so clearly he is leaving enough space to avoid collisions.

The interesting thing for me at various demos has been the car/pedestrian relationship thing. Many humans won't slow for pedestrians unless they are clearly coming off the sidewalk and into the traffic lane, and even then some of them won't slow if they feel like they will be past them before the pedestrian would intersect with their car. Robo cars on the other hand immediately slow down when their algorithms suggest that the human might be about to cross the street.

Because of this, another human driver won't expect the car ahead to slow suddenly because of the loitering pedestrian (expected behavior of another human driver) and so will be "surprised" by the braking of the car in front of them. There will be a moment of cognitive dissonance while the human is trying to normalize their perception that slowing down is not 'normal' and the fact that the car ahead is now rapidly approaching their front bumper. At which point the impending collision overrides the dissonance with a self preservation reaction to brake hard and stop.

>>:-) You haven't driven around SF much perhaps? But notice he said "almost" not "did" so clearly he is leaving enough space to avoid collisions.

Have driven plenty in big cities and small towns. You should always leave enough space in front of you in case somebody suddenly stops.How much space you leave in front of you depends on how fast you are going. At least that was drilled to me by more experienced drivers. I think it was even part of the DMV exam. I have not driven in San Francisco. How bad is it? Do they drive bumper to bumper?

> How much space you leave in front of you depends on how fast you are going. Right?

In city traffic of any appreciable density the type of following distance that you can discuss on the internet without getting flak from the holier than thou types will quickly fill itself with cars pulling off of side streets or merging in front of you.

"Your safe following distance is my opportunity." -Jeff Bezos

I'll be honest - I don't respect people who tailgate or follow too closely. I think they're selfish and self-conceited.

People who think - I"m more important than you, I don't care if I kill you, as long as you don't inconvenience you.

The law (and insurance companies) are pretty clear on this (at least in Australia) - if you rear end somebody, it's nearly always your fault, for being silly enough and not leaving enough gap.

They have educational campaigns on leaving enough gap (it's meant to be 3 seconds). Things happen, and people have to emergency stop.

It's taught to every driver.

The problem is that a 3 second gap is large enough for someone else to put their car there, so that's what happens.

And no matter how many times you build that 3 second gap, someone will keep taking the space. What ends up happening is that your 3 second gap means people will try to go around you (if this is the freeway) and then get right in front of you and eliminate your 3 second gap.

I think eventually you'll get into a steady state solution where you'll be limited to 20mph on a 65mph freeway because that's all the room you'll be given - if you follow the rule of law exactly.

Instead, most bay area drivers keep about 40-70ft between cars when going 70mph. Juuuust enough to react in time to an emergency stop. It's a little silly but it's the only way you won't get cut off constantly. Only other way to not get cut off is to go quite slow and be behind traffic speeds.

My car has adaptive cruise control. It automatically paces the car ahead with about a 2-second gap. It is absolutely wonderful for reducing stress and workload in heavy traffic. But the other cars... Someone will see the gap and race around me to fill it, as if I wasn't driving exactly the same speed as the car ahead. Causing my car to slow a bit to rebuild the gap. The next car back sees that and decides the first car passed because I'm an obstacle, and copies them. And so on. Until I'm driving 5mph slower than traffic, with a constant stream flowing around me.

That is not the steady state. When a car gets in front of you and eliminates your three second gap, it does so so it can continue at the speed of the traffic ahead. For you to be limited to 20 mph, the other cars would have to get in front and slow down. I feel that in practice I never have to do more than take your foot off the gas once in a while.

So, your experience in Australia, applies to a city that has a population of 870,000 residents, and a total daytime population of over 2,000,000 all in a 46 square mile area, also with nearly every single intersection controlled in some fashion - no joke, pretty much every intersection has a stop sign or signal lights.

So based on this you give us your throw-away "3 second gap" comment, helpfully telling us that this is the law and something something emergency stop etc drive safe?

With an average speed of less than 10mph, and a very dense city, your normal traffic "rules" don't apply here. Don't even pretend you can understand how things are here without experiencing them.

Your post essentially means "it's okay to hit people sometimes; our city wouldn't work otherwise".

> Your post essentially means "it's okay to hit people sometimes; our city wouldn't work otherwise".

This is trivially true! Otherwise cars would not be allowed on public roads.

When it comes to cars, it's always about tradeoffs and acceptable risk.

>When it comes to literally EVERYTHING civilization does, it's always about tradeoffs and acceptable risk, regardless if whether you personally can identify those trades and risks.

FTFY

I have driven in San Francisco. As a rural Midwesterner accustomed to people leaving space between cars and slowing to allow people to merge onto the freeway, SF drivers are among the rudest I've had the misfortune to mingle with, and I've driven everywhere from my home in Michigan to Canada, the East coast, the deep South, the mountain states (one of the nicest places to drive, in my experience), Canada, Mexico, China, and California. Only in the outskirts of Shanghai have I experienced drivers that were less cautious and less respectful of my car's right to the road than those in San Francisco.

Fortunately, when I was in San Francisco, I was on vacation and therefore content to simply get to my destination a little later, taking back roads and continuously rebuilding the space in front of me, avoiding rush hour like the plague - but wow, those automated cars are getting a stress test. I just hope they're not programmed to drive like the Californians building them!

Come to Los Angeles / Orange County, where a blinker is a signal for the driver behind you in the lane you are merging into to floor it. Coupled with 12-16 lane freeways this makes for good times.

Yep. Leaving adequate stopping distance is laughable when driving in LA. If you leave more than a few body lengths, cars from adjacent lanes will just swerve in front to gain a bit of ground until the gaps are gone. Maybe all self-driving cars should be required to display "student driver" signs for the next couple of decades.

New Orleans, South Florida, have much more aggressive driving cultures. Bay Area is also kind of average in comparison to much of the northeast.

This so much this. Forget America or even the west, in Beijing you have to be prepared for anything to happen at anytime. So everyone drives “on edge” so to speak because you never know when some idiot will stop and back up on the expressway cause they missed their exist or some electric trike will barge straight into oncoming traffic. On the other hand, yielding is almost unheard of and traffic will rather try to sway around pedestrians.

You'd think a relatively authoritarian government would be able to stop people from doing this sort of thing. It's kind of amusing, from that perspective

China is authoritarian until it’s not. Most authoritarian countries are weak on rule of law and more aptly practice rule by law, where laws are just used to control the people vs. applied fairly. So laws are just used to get what officials want (e.g. get rid of a pesky dissident), and most of them don’t care about traffic safety.

and even then some of them won't slow if they feel like they will be past them before the pedestrian would intersect with their car

I see this all the time. I'd like to point out that this is illegal driver behavior. You can be ticked for it. It is also very dangerous for pedestrians, since it encourages people to cut the tolerances closer and closer. I've had people nearly run over my feet doing this.

Humans will have to adapt to the AIs. Large corporations generally get what they want, eventually.

Good thing is, humans are good at the adaptation bit.

The problem with autonomous vehicles at the moment is that they act like a paranoid schizophrenics with the reactions of a F1 driver, anxious to apply full braking force for no discernible reason in less than 5ms, placing everyone in and around the car in danger.

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