This diagram changed how I think about following distance: https://entropicthoughts.com/keep-a-safe-following-distance

Unless it’s in Netherlands, where it’s 100%.

Incredibly frustrating, and I've driven all over North America - there's practically no major city where this doesn't happen. If you're not maintaining a safe following distance on city/residential streets, that's a different matter.

Just a few of these was enough that my "discount" was only a few dollars. I regret giving Progressive my driving data.

It's probably the best single thing anyone can do to improve safety. It also reduces wear-and-tear on your car, and increases your fuel economy as a side benefit.

Why hasn't gamification of safe driving habits been built directly into the car itself before now?

I'd love to see them incorporate visual detection of vehicle crash debris as well. There are two intersections in my area that consistently have crash debris like broken window glass and broken plastic parts and license plates from crashes. I know they are dangerous, but I don't know if autonomous vehicles also know that they are dangerous.

From the article:

"Our analysis of road segments in California and Virginia revealed that the number of segments with observed HBEs was 18 times greater than those with reported crashes. While crash data is notoriously sparse — requiring years to observe a single event on some local roads — HBEs provide a continuous stream of data, effectively filling the gaps in the safety map."

So we don't have to wait until an accident actually occurs before we can identify unsafe roads and improve them.

Google/Apple probably collect a massively larger amount of data than those other companies, putting those other companies at a risk of losing future revenue.

Between Google and Apple pretty much every car in the US is monitored.

it's largely a problem in the left lanes, thats where drivers will bunch up most. the subjective feeling is mostly a reptile brain issue though, the feeling you're getting done over. driving is 90% id, sadly.

I will never understand why this is so rage-inducing for people.

Changing lanes is a necessary part of navigating, even during busy traffic. People on an on-ramp will need to get in front of somebody. People needing to move back to the right because their exist is coming up will need to get in front of somebody.

Your lane is not a birth right. Let people merge.

> you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute.

This happens because literally everyone is tailgating each other so hard that the gap in front of you is the only gap that exists for people to change lanes to either get on or off the highway.

Has this been studied in isolation? Many of the tools that notify upon hard braking also are used to impose financial penalties for doing so... I suspect people may be reacting to the financial incentives.

Is it that hard braking events are broadly indicative of surprises of lots of sorts, and so it happens that the only way to eliminate them all is to develop a full range of defensive driving habits?

More Goodhart's Law or Serenity Prayer?

... How do people not notice that they are braking hard?

if we could bridge that gap, the economic incentive for municipalities would be massive lower accident rates mean less property damage and fewer expensive liability lawsuits for the city. it's basically a potential safety feedback loop that just needs the right data sharing protocol to actually kick in.

It does require patience to do this, because all aggressive drivers will use the space you provide. But ultimately the travel time difference in flowing traffic is negligible.

Google is measuring where on the road most hard braking events happen.

Insurers measure who is having the most hard braking events.

I remember being too aggressive when I got to the Bay Area, and learning how nice it was to be let into the lane I needed to avoid being forced on a 5mi U-turn. When visiting back home I was too nice and people told me so.

I've reached a balance. Aggressive enough not to be taken advantage of, but being nice to drivers in need, specially when it doesn't really change things for me, like when letting a driver in costs me nothing because of how bad traffic is.

There is a minor financial aspect (price of fuel), but I’m far more interested in seeing if I can get a better “green score” at the end of the drive.

Most people have near zero defensive driving skill, and view someone pulling out in front of them as "nothing I could have done", when the dashcam shows the offending driver showed 5 signs of pulling out ages before the accident occurred.

The cause of hard braking isn’t mutually exclusive: bad driving or bad road design.

Have a look at a few dash cam accident videos [1]. There are many maladaptive patterns of behavior, but a frequent one that the average good driver can improve on is limiting speed on two occasions: when approaching a blind spot, and when passing stopped or slow traffic.

That second one gets lots of otherwise good drivers. They seem to think that by limiting their speed vs slow/stopped traffic they'd be encouraging people to dart in front of them. Which is somewhat true. But with limited speed, that's an avoidable or less injurious accident. By gunning it past stopped traffic, you make the accident unavoidable and more serious.

[1] https://www.youtube.com/@IdiotsInCars1

It’s this obnoxious audio warning that tells me I had a hard breaking and it’s 9/10 because I stopped at a red light that I would not have made on yellow. And then it sends me tips and reminders about reducing hard breaking events and it’s annoying. I know they have done the analysis but it detects moderate hard breaking which is frustrating. One of those things that I am sure in net is positive but perhaps slices of the population it does not benefit.

of course if they change such that they don't break hard when needed that is bad, but if the change such that they don't need to break hard in the first place because they slow down in places that are dangerious that is the point.

Having driven all over NA, and Europe, I find it more prevalent in NA. Less distance, more people in large pickups throwing their weight around to make someone move out of the way.

And a design of giant freeway interchanges that require shifting lanes.

E.g. on the 405 in CA. 7 lines going South from the Valley towards Santa Monica.

That's 7 lanes you need to cross if you're in the HOV lane.

I think it will also back down the cruise control (if set) if it detects that you are gaining on the car ahead. That might be MILs Toyota though.

I learned the "two second rule" in Driver's Education 45 years ago and generally follow that. Nothing more annoying than having the car behind you riding your bumper.

The only possible fix as a driver was to try to develop an intuition for spotting “stale” greens and start slowing down despite the green, anticipating the yellow.

I feel at least partially vindicated by the fact the lights in question eventually had their yellows extended.

Also, a bad driver mis-breaking trips the cars behind into breaking too, which multiplies the energy waste and may also cause accidents through fatigue.

Mare experienced drivers will give you more leeway to avoid tapping the brakes with you, or simply go for a staring overtake.

Where Google/Apple's coverage is quite valuable is for near-real-time speeds for atypical events -- say like yesterday's Super Bowl. But that's not what this blog post is about -- this post is about a well-established pattern that can be identified with historical datasets.

All that to say that vendors sell a wide variety of data products to transportation planners, but just because Google is now entering this niche market doesn't mean they'll be "the best" or even realize what their strengths are.

It also shows how close you are to the car Infront in "car length" units with a nice big indicator and the adaptive cruse control will follow that distance mostly on its own between 30-100mph

The only people who cut too close to me are driving recklessly.

That being said: If you're in the mode where people are constantly changing lanes in front of you, think a bit about how you're driving: On the freeway you're supposed to stay to the right except to pass, and you're expected to keep up with the flow of traffic. Are you going slow in the left lane? Are you driving too slow? Are you camping in the right lane by a busy interchange?

I recently pulled my travel trailer from OK to Charleston, SC and back. I never drive over 65 MPH for safety and MPG reasons. I always stay in the right hand, slow lane except if I have to take a left lane exit. Since I was always driving slower then everyone else, not once did I have to hard brake. Tailgating is a choice and a dangerous one.

I was never honked at, even by the crazy semi truck drivers.

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.

Somebody on the radio said that "just set the adaptive cruise control to max distance and your windshield will last way longer". It does feel overprotective at times, especially in slow and dense traffic, but I think there's a nice point in general.

What will happen if there's some oil spill or brake failure at the point you think you should break hard?

I am so glad it hasn't. Data point of one, but gamification now has the opposite effect on me: it's such a well-worn pattern that it just annoys me. It was great when it was novel. I wonder how many others feel the same but without sampling it's hard to know.

I'm all in for traction control and to some extent ABS, but braking hard and upsetting the car's balance when you don't need it is dangerous.

Calling that person an idiot for your misunderstanding is not cool.

In the rural case, the offramp will branch off first and the on ramp will be after the overpass and the drivers taking each never meet.

In the space constrained case, theres one extra lane that serves both, where the drivers taking the on-ramp cross paths with those taking the off ramp. This configuration is absolutely cursed!

Example: open space on either side of the road, tends to encourage people to drive faster.

Closing that space (whether by buildings, shrubbery, etc ) will slow the speed.

But I will say there are also “obvious” bad designs - the rare far to short on ramp to merge, where drivers don’t understand how to adjust.

Or the one I most frequently encounter are “blind spots” created by the speed of an intersecting road, where a mirror may be attached to a pole / tree, or a sign reminding people to look left right left, or even instructing where cars should be beyond for a safe pull out.

I know of one intersection near me that both has markers on the road(don’t pull out if cars are at or beyond this marker), and a reminder about looking, but still has a high frequency of accidents.

Much of being a good driver is just awareness.

One time my light turns green, I don't go. As my wife asks what I'm waiting for, a pickup blows the light. We weren't the first car at that light, and years later she still talks about how there's no way I could know. Well, I didn't get us t-boned at 80 so I must have done something right.

But now even when in a car, I retain that "I'm invisible" mentality, which makes me much more aware of what other drivers are doing, and much more skeptical of their ability to make good decisions. This has saved me several times.

I realize this may come off as victim blaming, but I feel you should have an obligation to not endanger yourself even if by the laws of the road you are technically in the right. I would rather get cut off by and idiot and be at my destination thirty seconds later than having to deal with car repairs even when it is legally speaking not my fault.

Yeah, if you want to do that, it would be helpful to know whether a financial incentive is required for the effect or not.

It’s still out of the norm braking for my style of driver but from what I see on the road, people drive aggressively like this. Especially in the US.

I do both and I am constantly surprised at the lack of situational awareness of drivers when I’m a passenger in their cars.

I think truckers probably get the same thing too.

Fuck all of that.

Inb4 deaths per mile driven, I'd argue higher VMT in the U.S.A. only proves the point - too many cars being driven too much because of silly land use. High VMT is acutally a symptom of a dangerous mobility system as much as a cause.

One thing HPDE taught me is that most people under brake in dangerous situations because they simply don't know the limit of their vehicle nor the sensitivity range of the brake pedal.

The hard braking heuristic makes sense when estimating risk of road segments, but not as a proxy for driver competence.

It's almost as if the purpose of the system is what it does.

This is very state dependent, if we are talking about legality.

In WA state, for example, there is no "flow of traffic" law or similar. The limit is the limit, and any excess of the speed limit is illegal regardless of what all other drivers are doing. So even if the right/slow lane is going 100MPH through the 70MPH zone, you are legally expected to still go 70.

Thankfully we do have laws against left lane camping, but I rarely see it enforced.

#trustmebro

I can easily shave 10% off my commute by lane changing to avoid the lanes where turn lane traffic tends to back up into the travel lanes, ramp traffic and "problem people". I test the null hypothesis several times a month by carrying bulky topheavy cargo that precludes a bunch of lane changing without more effort than I want to put in.

I don't think there's much to be gained by simply lane changing to chase fleeting gaps in traffic. The wins and losses will probably mostly cancel out.

Obviously the calculus changes at rush hour when the exit ramp (and highway) begin to back up. And in those cases, yes, of course the correct answer is to slow down before the ramp, even if it means impeding traffic. (Or take the next exit.)

Just for fun, there's also a very short entrance ramp onto a 65mph highway in this city, which requires you to accelerate uphill from a stop sign with a very limited runway (~200 ft.) This entrance has been responsible for far more accidents and crashes than the exit I initially described.

That drives me nuts. When you put x amount of force into the brake pedal, you should know you're going to get y amount of deceleration. Don't double the brake boost just because you decided it's an emergency due to some opaque criteria.

More like a few seconds.

Every car that merges in front of you only costs you their following distance. If the average following distance is 1 second, then you are simply 1 second slower than you'd have otherwise been. So unless this is happening continuously every 30 seconds on your 30 minute commute, you will lose less than a minute.

The "but if I kept reasonable following distance, people will keep merging in front of me and I'll lose time" excuse is pretty thin given this analysis.

And an insurance claim can easily eat 40 hours of time between the insurance companies, other lawyers, buying a new car, medical appointments and recovery. That's 19,200 minutes you won't get back, or about 52 years of driving 1 minute slower each day.

Slow is smooth and smooth is fast.

And from personal experience in some places, keeping such a buffer, in some traffic conditions would just literally be impossible. There are sometimes enough aggressive drivers such that they can just consume it faster than one would be able to create it. It is simply not always the case that you have sole power to create and keep the recommended buffer size (although very often it is and you can).

I keep a decent buffer whenever I am able, but at some point, you have to bow to road conditions.

Because you were towing a camper and "slow and in the right lane" fits people's mental model of how recreational/nonprofessional heavy traffic or otherwise "handicapped" vehicles ought to behave.

When you have problems is when you behave to a standard beneath what other people expect from whatever kind of traffic you are.

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.

A slight increase in average speed really only makes a significant difference over long drives. (5 mph increase over a 10 hour drive can cut off 50 minutes).

Otherwise we are talking about small differences in efficiency.

(I would be very open to another opinion here.).

My opinions are formed by nearly ~2 million miles driven at this point, two different driving courses, and the motorcycle safety course.

One thing I truly think that’s overlooked is how reduced road noise in the vehicle cabin can both reduce driver fatigue, but also frustration in traffic.

I also think some of the car sensors (Subaru especially) that are trying to make you safer are notoriously bad.

I also find the random “coffee break” notice on Subarus frustrating.

My personal examples: “eyes on the road” - triggered frequently by one pair of sunglasses I have, looking left to check blind spot, checking mirrors, etc.

“Hands on the steering wheel” - triggered occasionally on long drives when I have been giving input, but very light input.

Unfortunately, sometimes over a 45 minute freeway commute, dropping back repeatedly means arriving 15 minutes or more later. Again, no big deal now, but it was somehow unacceptable when I was younger.

Similarly, people often don't like it when insurers track and score their driving. However, this allows insurers to offer lower insurance fees to more people by _not_ offering lower insurance fees (or instead charging higher fees) to people that are driving in a risky manner. This does of course assume a competitive market for insurance but I think in most countries that's a reasonable assumption.

There's nothing fairer than user-pays, especially when users can choose to pay less by changing their behavior.

I (an American) was on holiday and Switzerland and was explained the process of getting your license back if you lose it. It is a big disincentive to driving badly and putting yourself at risk of that, to be sure.

First, the insurance company incurs costs just processing the claim. If things escalate with the other party, they may even incur legal and court costs.

Additionally, there are some costs that are incurred regardless of fault -- like personal injury protection.

Even defining "who was at fault" is a complicated situation. A lot of people presume that it is as simple as: whoever the police issues a citation to at the scene is 100% at fault. But that's not the way things actually work. The way liability is assigned depends on the state, but in a comparative negligence state you could be proportionately liable for as little as one percent of the fault of the accident. Maybe someone else ran a red light, you entered the intersection on green, and hit them. You could end up sharing some of the cost for that, if it is found that you could have avoided the accident but decided not to.

And even after all of this, if the other party runs out of money, doesn't have insurance, or runs away at the scene, your insurance company is stuck paying the costs under their uninsured/underinsurred motorist coverage.

35 years without an accident on my record isn't because I'm a magnificent driver, it's because I always try to leave a way out for when something unexpected happens, because the unexpected _does_ happen.

The fact that some people may have the skill to drive more aggressively means nothing in the aggregate as far as insurance companies are concerned. If you are skilled enough to drive in that manner, you are skilled enough to avoid it as well. It's simply statistics.

The article stuff definitely doesn't.

Driving with bad drivers should incentivize you to follow less closely and require less hard braking, not more.

There's a motte where some poor fellow is always maintaining the car-length-for-every-10-mph rule and yet keeps being passed inside that distance by innumerable bad drivers the fellow is surrounded by.

I pity that fellow.

He has an excuse.

He also isn't observably real in any of my 21 years of driving in Buffalo, Boston, and Los Angeles.

I feel harsh for saying this, I am only saying it because A) this subthread is specifically about there isn't an excuse B) this stuff involves our lives. Thus, this is an appropriate venue because the people in the venue know what to expect, and poking at someone's thoughts on it may help them immeasurably.

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 ).

Yes! I feel like I can't shout this loud enough. In addition to maintaining a safe driving distance, just leave a little earlier. The stuff I've seen people do in order to save 20 seconds boggles the mind.

Unfortunately, I think commuters fall into a gamification mindset. They're trying to set a new lap record each day, and you can see the results just by driving (or walking) during rush hour...

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

I'd barely left the yard, certainly hadn't made it across town.

It went off when I actually did stop for a coffee, but went on again 15 minutes after I left the car park.

I have to say its various combinations of bings and bongs and beeps were about the most distracting thing I've ever experienced in a vehicle.

So much of road etiquette boils down to leaving adequate space so others can maneuver around you. Trying to optimize your travel by destroying any gaps as soon as they appear actually has the opposite effect.

But even if 2 dozen people go around you and creep into that following space, you've been cost like 45 seconds at worst. Better not to play the game.

I don't want to live on this planet anymore.

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.

You can't really say that without knowing the starting speed, or alternatively the distance. All you can say is that a 5 mph increase over a 10 hour drive with get you 50 miles farther.

People don’t usually act erratically for no reason. Maybe they suddenly stop because they see a deer sprinting towards the road off in the distance, and the person behind them didn’t see it. There are tons of reasons that look like they “erratically stop”, which are actually genuine safe behavior that the other may not know about.

However, on the rare occasion I've found myself going slowly in the right lane, it's stunning how incompetent most people are at merging. It's like they don't even consider looking for an opening in traffic, matching the freeway speed, etc. They just lumber in front of you at 43mph, and maybe, if you're lucky, look in their mirrors after they've already caused you to slow for them.

Sometimes I think it's just people's reflexive scarcity mindset that tells them "that spot must not be that desirable or someone would be in it."

Regarding the broader topic of hitting your brakes, I find that I can commute 20 miles in stop and go traffic and only tap my brakes a couple of times. Helps to pace yourself behind the car 3 cars ahead of you instead of the guy right in front of you.

Then use it? Mandate reaction speed tests or other driving mechanics competency evaluation (not road sign comprehension) and watch insurance margins explode.

The driver in my example did poorly and scored top marks in the heuristic.

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

If you do a comparison of a 600 mile trip at 60 vs 55 you’re pretty close.

But yes, to be pedantic and more exact, you are spot on that it will get you 50 miles closer.

But in real world examples,

If you’re traveling 700 miles.

65 vs 70, 70 will reduce your time by 43 minutes.

So in certain scenarios, 5 mph difference must be able to save you 50 minutes ! ;)

(I do understand your point, and you’re correct. I’m just poking fun at it- my point with the mph difference is because 50 miles doesn’t have the same translation for most people at 50 minutes, but is a more accurate data approach. )

Not a significant cost. But they sure as shit aren't getting what they think they're getting. Meaningfully farther ahead.

I now see it all as a risk assessment rather than as ritualistic combat.

> building a distance buffer", that is the proxy the insurance companies want to use for risk assessment.

The cam car did not need to have a hard braking event (HBE) to start building distance.

Even if they did, the insurance companies are looking for a pattern of HBEs to assess risk. I agree that there is a theoretical high-risk driver that never has a HBE because they always try to maneuver instead of breaking. There are other heuristics for this (high lateral acceleration, high jerk). And the ultimate heuristic: failing to avoid accidents, thus having a claim history.