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0 pointsyial1mo ago0 comments

This is accurate in many ways. I use the auto cruise feature on my car frequently and I notice several things happen unless I set the distance as close as possible (which I don’t like to do. ).

1. In any amount of traffic above “a few cars” people will cut in front of me, sometimes two, negating the safe following distance. Regardless of speed.

2. If I have a safe following distance while waiting for someone to get over. (I e they’re going 60, I want to go 70), if I have my distance set at a safe following distance, people are much more likely to weave / pass on the right. (My theory would be that the distance I’m behind the person in front of them signals that I’m not going to accelerate / pass when the person gets over ).

Disclaimer: I don’t usually have to drive in any significant traffic, and when I do (Philly, New York City), I’m probably less likely to use the automatic features because the appropriate follow distance seems to increase the rage of drivers around me.

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Noumenon721mo ago

I always wonder why so many people observe this when I never have. It makes no sense logically; it's the speed of the car in front of you that determines whether they should switch lanes, not the size of the gap behind it. There is no reason for them to cut in when your lane is no faster. Perhaps you are just the sole person leaving enough room for people to execute needed lane changes.

At any rate, even if people are continuously going around you like water going around a rock in a stream, you only have to drive 2 mph slower than traffic to constantly rebuild your following distance from the infinite stream of cutoffs. But my experience is the majority of following distance is eaten up by people randomly slowing down, not cutting in.

yialOP1mo ago

In the auto cruise example, it’s leaving perhaps 2 - 2.5 car distances. In close traffic the average human I would bet is leaving 1 or less then 1.

The issue is not that I can’t rebuild the following distance, the point I’m trying to make is that even if I constantly rebuild the following distance it sets off a cascading effect.

I’m following at set speed, car cuts in front, hits brakes, I now slow down, car behind me slows down, I rebuild following distance and car perhaps 7-8-9 cars behind me repeats because at some point the cascade magnifies to a larger slowdown behind.

Can I mitigate this by manually letting my distance be closer for a time, and slowly easing to larger ? Yes.

But if I allow the car to do it automatically, it will increase the follow distance at a rate that causes a cascade in tight traffic.

Though - I do think with these discussions on HN- it does depend on where you’re driving.

My experiences are centered on East Coast, thinking of route 80, 81, 83, etc. or Philly / New York City.

The driving experience is radically different in California, Florida , or the mid west.

I would say when driving in California people seem to navigate traffic better. (SF, LA) then on drivers on 80/81/83. (Or perhaps it’s due to better designed roads ).

ninalanyon1mo ago

> In the auto cruise example, it’s leaving perhaps 2 - 2.5 car distances. In close traffic the average human I would bet is leaving 1 or less then 1.

At 60 kph (16.7 m/s) 1 car distance (about 5 m) is less than one third of a second. Even 2.5 car lengths is less than a second. I use traffic aware cruise control on my Tesla set to the maximum separation which is about three seconds, so 50 m at 60 kph.

Three seconds separation is in fact the recommended following separation in most European countries and in Germany in particular 0.9 seconds or less can result in a hefty fine, see https://en.wikipedia.org/wiki/Two-second_rule

In the UK some stretches of motorway have chevrons marked on the road indicating the required spacing at the speed limit.

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VladVladikoff1mo ago

Just drive in the slow lane and you won’t have this problem. The people cutting in front of you rarely want to be in the slow lane.

yialOP1mo ago

I do drive in the slow lane frequently - and this still occurs. (My go to is to set my cruise 6-9 mph over the speed limit, if passing to smoothly pass and get back over, and spend as much time as possible in the slow lane. )

However - I will say most of the roads I’m on are 2 lanes of traffic. I will have to experiment and see if this doesn’t occur when there are 3 or 4 lanes.

girvo1mo ago

The idea of cruising 15km/h over the limit is absolutely crazy to me. That will get you 3 points and a minimum $500 fine here. We have "average speed zones" too!

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michaelt1mo ago

> I do drive in the slow lane frequently - and this still occurs.

One part of your post was about people passing on the right. People won't do that if you're in the rightmost lane.

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bcrosby951mo ago

In Southern California the "fast lane" is the medium speed lane, and the "slow lane" is the actual fast lane. It's where people tend to weave in and out of traffic at 15-25 mph speed differentials.

vardalab1mo ago

I don't know you can find that traffic always bunches up. And if one is content to sit in the gaps in between, almost never anybody cuts in. I drove twice 1000 mile trips each way last year and it kind of worked. It's more of a mindset than anything else. Fastlane is not that fast or it would be empty, lol.

yialOP1mo ago

The fast lane isn’t always faster is very true! Haha

What I will say is some of this may be the difference between manual driving - and automatic.

If I’m manually driving - where my follow distance fluctuates more due to speed / traffic - almost no one cuts in.

If I am driving where I’m using the vehicle to maintain a perfect set distance, people cut in.

Again, anecdotal

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