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Comment by flavor8 | Hacker News Reader

> I see 2-3 accidents daily caused by your "alert" drivers rear ending cars.

Remind me not to drive in your neighborhood. (This appears to be hyperbole.)

"neighborhood"? Who commutes across a neighborhood as the full extent of their commute? I suspect it's within a rounding error. Driving across a city, however, I definitely see this. Daily. And "accident" I expect to mean everything from a light tap rear-ending to a full fledged crash.

People rear-end each other in my city every day. On my commute, I'll come across two a day. Wet days, a few more. The other five directions headed into the city I would expect to see similar statistics to my experience. Just listening to traffic radio, there's going to be at least five crashes around the city; almost always more. They don't report on fender benders.

About six years ago, I would drive from San Mateo to Oakland at least twice a week, after work, to meet my then-girlfriend. So that's down 92, across the bridge, and up to Oakland. It's about 30 miles, all on freeway, and at that time of day all in heavy (though not all stop-and-go) traffic.

I don't think I ever saw three separate rear-ends in a single drive. I can't say for certain that I ever saw two. I didn't drive it every day, but I probably did 100 such commutes.

You sound either like you're massively exaggerating or live someplace with apocalyptic traffic.

You drove 30 miles up 880 twice a week and never saw a rear-end accident? You should play the lottery. I don't know if I see three every day, but I do see one every week. This week's was some clown in the #2 lane, _staring_ down at his phone, rear-end into a stopped car at ~20 MPH. His car was completely totaled with one of the wheels spinning off to the shoulder.

A few months ago I saw a guy, face-down in his phone, smash into an existing accident that was already surrounded by fire trucks. That was amazing.

I didn't say I never saw a rear-end accident, I said I never saw three in a single commute and am not sure whether I saw two in a single commute.

The guy I was replying to said that he saw at least 2 every commute, often more. (Edit: Actually, sorry, 2 every day, not every commute).

How do you have the bandwidth to look at other drivers' postures while driving?

Here are the traffic stats for Canada[0]. In 2015 there were 116,000 "personal injury collisions". That is ~300 injuries a day across Canada.

The Greater Toronto Area has approx. 20% of Canada's population (~35M). If we assume that 300 injuries are evenly distributed across Canada, which seems unlikely due to how bad the driving conditions are on the 401 and DVP, there are ~60 injuries per day in the GTA of various severities.

I don't think someone encountering ~3 per commute during rush hour is unreasonable.

[0]: https://www.tc.gc.ca/eng/motorvehiclesafety/tp-tp3322-2015-1...

>I don't think I ever saw three separate rear-ends in a single drive. I can't say for certain that I ever saw two. I didn't drive it every day, but I probably did 100 such commutes.

I drive 30 miles through Chicago traffic on the Interstate everyday. I see at least 3-4 accidents per week (people pulled over to the side of the road, out of the way, or at the accident investigation sites.) Most of these are minor fender benders. I'm sure if I was in rush hour traffic for the full 4-6 hours (not just my 90 minutes of commute) I would see way more. They mostly happen in near bumper-to-bumper stop and go traffic (someone misses the guy in front of them stopping) or when traffic unexpectedly comes to a standstill from going 10-20 MPH.

The guy I was talking to said he saw 10 a week minimum.

Yeah, if you spend 4-6 hours a day in traffic, you'd see a lot of accidents. That... seems uncontroversial.

Every single day of this work week so far there has been at least one and as many as 5 accidents on the same 5 mile stretch of I95 headed in to Waltham, MA.

Every morning and at least two of the evenings. And the weather has been reasonable. I typically see 4 to 5 Teslas a day during my commute... driving sedately, and they aren't they ones involved in the accident.

Maybe we'll break the streak tomorrow and have no accidents.

Driving and down 280 over a year's time, once a year, there can be a single day with three separate fender benders. Appearing to have happened within a 30-min window of passing by. But never witnessed 3 to happen --like happening as I was driving.

Between San Jose and San Francisco on 101 pretty common to see at least 1 fender-bender per commute.

I ride my bike in the Peninsula. I personally witness 2-4 accidents monthly ranging from fender-bender/taps to full-on smash-ups. Maybe 2-3 daily is an exaggeration, but they're plentiful. It's a rare day that goes by where the major freeways don't have slowdowns because of wrecks. I'd be surprised if the typical commuter on 101 saw less than 1 per day on average, actually.

I'm in the UK, but I used to drive an hour each way to work which was about 25 miles. In a year I saw like one accident and that was someone being rear-ended in slow moving traffic.

Just take any job that requires a significant highway commute, you'll see more than that.

Whenever you get full speed traffic occasionally interrupted by traffic jams (from whatever cause, other accident, tolls, weather, low angle sunlight, construction, etc.), you'll get a higher incidence of rear-enders. Especially when the tail of the slow/stopped traffic is at a point just past a hill or curve.

I got rear-ended myself some years ago in just such a situation, clear sky & dry road. The traffic ahead had slowed dramatically driving into a section where the bright, low winter sun was in everyone's eyes, we couldn't see that before the gentle bend & rise in the road, I saw the slowing traffic & had to brake hard, the person behind me braked late and hit me even though I'd tried to stretch my braking as much as possible to give her more room. There was another similar accident minutes later just behind us.

This kind of rapid-slowing situation in tight-fast traffic will likely even get out of hand even for automated cars, unless there is car-to-car communication. This is because of the slight delay for each successive slowing car in the accordion-effect accumulates to the point where eventually the required reaction time decreases and required deceleration rate increases past the performance envelope. At that point, a crash is inevitable.

With car-to-car communication and automation, the last car in the pack can start braking almost simultaneously with the first one and avoid this.

So, no, it's not hyperbole, it's ordinary.

rapid slowing is fairly common in 280. I find it safest to be on the left-most lane, where you can use shoulder to get you a safe stop. rapid slowing is one reason i'd probably get level-2 autonomous car.

"I got rear-ended once in fine conditions" != "I pass 2-3 rear-ends on my commute every day"

I didn't say it was -- I opened by agreeing, then also provide my example, as a lead-in to the car-to-car communication point.

And yes, when you have an urban highway commute of any distance, it is not unusual to see that many crashes. maybe not every day, but not far off, and enough that you cannot rely upon commute times, precisely because the crashes are so unpredictable.

You might try actually reading other posts before replying with trivial inaccurate potshots. sheesh

>This kind of rapid-slowing situation in tight-fast traffic will likely even get out of hand even for automated cars, unless there is car-to-car communication. This is because of the slight delay for each successive slowing car in the accordion-effect accumulates to the point where eventually the required reaction time decreases and required deceleration rate increases past the performance envelope. At that point, a crash is inevitable.

Is this really true?

It seems like, as long as the following delay between cars is greater than that reaction delay, there should be no such "accordion effect."

I don't think car-to-car matters. You can't rely on it being accurate or present. The car will simply have to drive in such a way that it can always stop within the stretch of visible clear road.

Yes, if you can stay out of Los Angeles, I highly recommend it.

2 is average for about a 60 mile drive during slightly off-rush. I suspect rush is higher.

And certain areas just seem to attract idiots.

See meaning drive past, not "observe the collision."

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