[harshaw]

Nice research. This is fairly well known in insurance circles. Most auto insurers that do telematics consider hard braking the strongest indicator of risk. One of the things that we do at work (Cambridge Mobile Telematics) is build tools to deal with this risk. We have apps that monitor driving and we play a tone to indicate that a hard braking event was detected. Simply letting people know that they had a hard braking event is an effective mechanism for behavior change (other companies have similar tech)

[advisedwang]

Insurance is thinking about hard braking as an indicator of a driver with riskier behaviour. Google is showing that it can also be an indicator of risky road designs. These actually kind of point in opposite directions in terms of the causes of hard braking. The certainly can be used in different ways.

[JimBlackwood]

They point in opposite directions because they’re not measuring the same things.

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

Insurers measure who is having the most hard braking events.

[tiagod]

Problem with insurance companies measuring risk this way is that local government externalises costs of bad road design to the people who are unfortunate to have to drive there.

[wongarsu]

Makes you wonder why there aren't more insurance companies out there using their data to lobby local governments to fix their road design. They have all the data to find hotspots, and reducing accidents would increase their margin.

Maybe this would require an insurance company to have outsized market share in a specific area so they are the main beneficiary of the improvement

[DoctorOetker]

It should also be generalize to when (for example a specific corner during dusk or dawn), and for insurers what would also be an important factor would be what other cars are nearby at the hard-braking event, it's not exactly productive to flag the chicken in chicken-or-dare scenario's.

[rogerrogerr]

(Though for an insurer, it’s the same thing - whether you’re risky because you’re a bad driver or because you drive on poorly constructed roads or around other poor drivers is inconsequential to them)

[mschuster91]

Yeah well fuck insurers. We are supposed to get spied upon by our cars with their blackboxes, by our insurers, by Google, by national security services of various countries... and what do we get in return? Dinged for other people's bad behavior which we cannot reasonably control. Either you follow the car in front of you very closely and get hard braking events, or other people switch lanes in front of you and in the worst case slowing down during lane change, provoking yet another hard braking event.

Fuck all of that.

[chad_oliver]

Credit scores are universally hated but they make it possible to offer lower interest rates to more people. Without credit scores, fewer people would have access to credit.

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.

[littlestymaar]

> Credit scores are universally hated but they make it possible to offer lower interest rates to more people.

That's probably true in theory, but not in practice, given how high US credit interest rates are compared to European countries for instance.

> Without credit scores, fewer people would have access to credit.

Too many people having access to credit is exactly how we got the worst financial crisis of the century, so it's not really something to brag about… People talk about US public debt a lot, but private debt is even more worrisome.

[cucumber3732842]

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

If user pays is so fair why does anyone who could access credit or liquid assets in excess of their state's minimums have to pay hundreds to thousands per year for auto insurance?

[AlotOfReading]

Most states allow you to go without insurance by fronting the cash. It's called self-insurance. You put up some minimum amount, file a form with the state DMV, and keep the approval certificate in the vehicle like normal.

It's relatively unknown for individuals because most people have no desire to lock up tens or hundreds of thousands of spare dollars just to avoid car insurance. As far as I'm aware it's primarily used by rich collectors who need to insure large collections that don't fit more traditional insurance profiles. Much more useful for businesses.

[chad_oliver]

That's an entirely separate issue, isn't it? In my country (New Zealand) there are no requirements to have auto insurance. If you don't have insurance and you hit a million-dollar car you're gonna be in an awkward situation, but that's a risk you're allowed to take.

Note that you _are_ legally required to pay your annual ACC levies, which fund no-fault cover for injuries. However that doesn't cover property damage.

[shepherdjerred]

So, what's your proposal? What should insurers be doing differently?

[mschuster91]

Operate like they did before they had access to surveillance technology that would have made Gestapo and Stasi blush

[cucumber3732842]

This. If you're nearly "perfectly" pricing risk on an individual level then you defeat the point of insurance which is to pool risk.

If my hypothetical cost over an N decade period is within a fraction of a percent of payouts in that time what do I gain by paying for insurance other than creating a principal-agent problem?

[Sharlin]

Some road designs are risky because they encourage risky behavior. And "risky" is relative. A good driver should recognize risky road segments and drive even more defensively than normally.

[yial]

This is true - but it’s hard even for “good” drivers to always understand especially on roads they might not be familiar with.

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.

[morkalork]

There's some that are purely due to space constraints, favourite pet-peeve example is a highway with an overpass crossing it.

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!

[alex43578]

A driver who frequents risky roads is a concern to insurers, just as a driver who has risky behaviors.

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

[jstanley]

Similarly, a road that is frequently travelled by risky drivers is a risky road!

[kube-system]

This is part of the reason insurers include zip code in their risk profiles.

[buckle8017]

Driving on bad roads is just as bad for insurance as a bad driver is.

[pavel_lishin]

My mom had a device installed in her car to get a discount on her insurance, and she was always upset at the hard braking thing - whenever she did it, it was because another car was doing something unsafe that she couldn't control, like pulling out in front of her.

[avidiax]

Some amount of that is inevitable, but there is another level of defensive driving where you anticipate poor behavior and arrange that it won't cause an accident.

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

[thomasguide]

Without wanting to paint with too broad a brush, I would say in my experience driving in 10x countries, U.S. drivers, being most habituated to spending their lives in cars, drive in the most distracted, least careful way. Especially in places where the typology is the U.S. default of low-density, car-oriented sprawl. Accordingly there are an appaling number of deaths and injuries on the road: 1 in 43,750 people dies each year in the U.K. in automobile accidents vs. 1 in 8,500 in the U.S.A.

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.

[michaelcampbell]

Add to that the relative ease to get a license in the US, and the level of punishment for breaking the laws.

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.

[maest]

Coming from outside the US, I was shocked to see how many drivers were on their phones _while the car is in motion_, scrolling Instagram or similar.

[sigseg1v]

Adding on to this, a common reaction I see to online videos of driving incidents is "why did this person just stop? of course you are going to crash into them. They shouldn't have stopped" and many people agreeing with it. It seems they are blind to the fact that if the following driver was using a safe following distance and speed, they should easily be able to stop, making the incident the fault of the driver following too close, not the one stopping.

[duderific]

I haven't checked on this in a long time, but IIRC, the insurance company will always blame the person in back in a rear-end collision, for just this reason. A rear-end collision should always be avoidable.

[SoftTalker]

Usually but not always. A common insurance scam is to pass a car, cut in just in front of it, then brake hard causing a collision. Dash cams video is a good thing to have to fight this if it happens to you.

[hananova]

No, even then. If a car cuts in front of you, you have at least a few seconds of time to start making space for them, and once they are in front of you, you should immediately make a safe amount of space between you and them.

Yes, in a country where safe driving is not internalized you will inevitable have someone rear-ending you while doing this, but if the options are "accident where you're at fault" and "accident where you're not at fault", pick the latter.

[ip26]

Some degree of road safety depends on predictable behavior. I haven’t seen those videos, but suddenly executing a panic stop on the freeway for no good reason at all increases everyone’s risk, even if the car behind you is following at a safe distance. Obviously the following driver bears the most responsibility, but erratic drivers shouldn’t be held to be morally blameless.

[californical]

> erratic drivers

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.

[tristor]

People act erratically all of the time on the road because they're on their phones while driving instead of paying attention.

[infecto]

People also don’t realize that just because you can does not mean the insurance will side with you 100%.

[geocrasher]

I learned next-level defensive driving by bicycle commuting to work 5.5 miles each way on busy roads in rush hour traffic. On a bicycle you're invisible, and if you expect any less, you're going to get hurt. As it was, I had some very very close calls- at least one of them had the potential to be fatal. Ironically, the only time I ever crashed was my own fault.

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.

[redanddead]

>I learned next-level defensive driving by bicycle commuting to work 5.5 miles each way on busy roads in rush hour traffic

please stop doing that geocrasher

[grog454]

The landing page video's first incident is a car coming from behind and from the right, cutting off the filming car. The filming car didn't react at all when instant (but measured) braking would've been safer to start building a distance buffer.

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.

[ominous_prime]

It certainly makes sense as a proxy for competence across a diverse population for insurance purposes. You have a baseline of hard braking events that a competent driver may encounter under normal circumstances. If a driver routinely exceeds that number, they are either unable to correctly estimate closing distance and reaction times, which makes them higher risk for causing accidents, or they are driving abnormally aggressively, which also makes them a higher risk for causing accidents. If you consistently put yourself in situations where hard braking is required, it doesn't matter what your skill is, you've reduced your safety margins and an accident is statistically more probable. You said it correctly with "would've been safer to start building a distance buffer", that is the proxy the insurance companies want to use for risk assessment.

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.

[grog454]

> You said it correctly with "would've been safer to start building a distance buffer", that is the proxy the insurance companies want to use for risk assessment.

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.

[avidiax]

I assume you are referring to this video: https://www.youtube.com/watch?v=sEpHyMtDcPY

> 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.

[Sohcahtoa82]

> 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.

On any modern car, just push it all the way and let ABS and stability control figure it out, and don't let the vibrating brake pedal spook you into releasing it. That's just ABS doing its thing.

Really though, getting a license is too easy in the USA. We really need to require some sort of car control course, including obstacle avoidance in the rain. Would be really nice too if it included an obstacle avoidance course in two cars: A huge SUV or pick-up truck and a more reasonably sized sedan. So many drivers think they need a huge vehicle to be safe while being completely unaware of how well smaller cars can likely avoid the crashes to begin with. Would probably get really expensive really quickly, though.

[pibaker]

One thing I noticed among dash cam videos is very often the person recording and publishing the video will keep on driving closely behind another car that is clearly driving erratically. Maybe he will honk, but he won't brake or leave any safety distance, and seconds later the idiot's car, which has been behaving weirdly in front of him the whole time, causes him to crash.

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.

[WarmWash]

If you take a seasoned motorcycle rider and put them in one of those dashcam subs, they'll rip their hair out.

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.

[doubled112]

At one point in my life I rode a bicycle 40+ km per day. I see things nobody else seems to and I think that has a lot to do with it. I cannot win the collision.

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.

[dghlsakjg]

Cyclists too.

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.

[matsemann]

Same, I cycle everywhere and almost feels like I've developed a sixth sense for when a driver will do something stupid.

[organsnyder]

I'm definitely a better driver because of bicycling. You gain new skills when you know that you're going to come out the loser in almost every collision.

[cucumber3732842]

If you cycle and it doesn't make you a better driver (and pedestrian) you're probably a bad driver and a bad cyclist.

[dgunay]

Very true. There is a "body language" to driving. I can often predict when someone will change lanes before they ever turn their signal on (if they even do that) by the way their speed changes and they drift a bit in their lane as they shift their eyes to their mirrors.

[RupertSalt]

A seasoned motorcycle rider should be unable to rip out any hair, due to safely wearing a helmet!

[Mawr]

A helmet is priority #100. If your helmet ever comes into play, you've fucked up so bad it'll probably not help you much.

[kube-system]

Drivers often believe that their insurance rates should be based solely on whether they follow driving rules, but the risks to insurance are not isolated to this. Someone can follow every rule perfectly, but if they are involved in an accident they incur costs for their insurance company.

[garaetjjte]

If they are not found at fault then indeed there's no cost for their insurance company?

[kube-system]

A common misconception.

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.

[SoftTalker]

There might be, if the at-fault driver is uninsured and you are carrying uninsured motorist coverage.

[AngryData]

It does cost them just to process the claim because the other guys side is unlikely to completely roll over if there is any chance to reduce the payout. Obviously its not as much as the claims themselves but it also isn't free.

[amanaplanacanal]

Yep. I have a friend that was plowed into from behind while waiting at a red light, twice within a few months time. Two separate intersections. Totaled her car both times. Her insurance rates went up, even though she was clearly not at fault.

[Mawr]

"Not at fault" as far as the law is concerned, is a low bar. If you're one of the last cars in a queue, you should be checking your mirrors for exactly this scenario. Throwing your hands up in the air saying "well the law says I did no wrong!" isn't the way. Unless you like getting into accidents.

Also, having two of the same type of accident twice in such a short time is so improbable, that I'm seriously doubting your friend. I'd say it's way more likely she braked too suddenly or has other bad driving habits that make such accidents more likely than that she got this unlucky.

[infecto]

I hate the warning myself and I use the app the parent is from. I also suspect I am an outlier in not having an accident in 20 years.

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.

[amanaplanacanal]

The lights should be timed so that you don't have to do that if you are driving the posted speed, but I know that's not always true.

[infecto]

No doubt but I think it’s two fold. Lights stink in that so many are setup not for safety so they rip through the yellow quick as possible. Second, I don’t think of these as hard breaking even but I am sure from a data perspective the cutoff is probably correct. Hard invokes a vision of an emergency brake event. These apps really capture any medium to hard brake event.

[jeffbee]

It is not possible to time lights that way over any significant distance in a multi-way fabric of traffic.

[kube-system]

> Simply letting people know that they had a hard braking event is an effective mechanism for behavior change

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.

[timbaboon]

Yep. We work with CMT and we’ve both done extensive testing on this. I think that often people don’t necessarily know what a hard braking event actually means, or how it’s quantified. Giving that realtime feedback helps close that gap in understanding

[mpyne]

When people learn to do things by reacting to inputs, they learn much better when the input comes soon after the action/inaction they are trying to train, rather than long after. When you can tie specific acts as a driver to a later financial penalty it helps you learn to avoid the specific acts, otherwise you'd stuck having to figure out in three weeks when the bill comes around what you were doing on the date the insurance statement flagged as a hard stop.

[dghlsakjg]

Anecdotally: I leave the fuel efficiency display as the instrument cluster display on the hybrid that I drive and it significantly changes both my acceleration and braking behavior.

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.

[bluGill]

Does it matter why? The important part is getting people to change behavior.

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.

[kube-system]

> Does it matter why? The important part is getting people to change behavior.

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

[alwa]

When you modify their braking behavior, is that enough to improve their overall driving behavior? Or do forward collisions and rear-enders make up substantially all of what the driver can control, so training the behaviors to reduce that type of near-miss reduces the driver's overall crash risk? To the point that it's similar to the safest tranche?

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?

[toast0]

Regardless of everything else, forward collisions are most likely to have the driver considered at-fault. Seems like reducing those in your insured population would reduce covered losses more than reducing collisions where your insured may not be at fault.

[Mawr]

> Is it that hard braking events are broadly indicative of surprises of lots of sorts,

Of apparent surprises to the driver. And since actual, factual surprises are extremely rare, if a driver is regularly being surprised, they're a bad driver.

[munificent]

How does one not already know that they had a hard braking event? Surely the jamming their foot on the brake pedal and the rapid deceleration would send an even more obvious signal than playing a chime?

[mecsred]

Obviously people know, but theres no impulse to introspect on why or how. Knowing that someone else knows you had a hard braking event taps in to our social brains to provide a much stronger response to the event. When we know people are watching we're more likely to try and justify our behaviour.

[redanddead]

that is fascinating

[infecto]

Have you used one of these apps before? They capture a lot more than emergency stops, what I would classify as the above normal brake effort but not hard braking. Im sure the data exist to set the cutoff but its a lot more than “jam your foot on the pedal braking”.

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.

[mhb]

What are these apps or devices? Where can I get one?

[infecto]

They are provided by your auto insurance company. A potential privacy nightmare, they track your movement. They also can get you a much lower rate.

[harshaw]

If you don't want to go through your insurance company you can check out an app we built called RoadClub. You get points for safe driving behavior - and you can get the hard brake alerts. Is it a bit annoying? yes. You can't just drive agressively - you need to give space to slow down. I still struggle with it.

[michaelcampbell]

Your faq doesn't mention anything about location data. I'd like to try it, but want to know about that first.

[dghlsakjg]

A lot of people don’t realize that what they consider normal driving is actually aggressive driving by other metrics

[ryandrake]

I know way too many drivers who have exactly two modes: Full brakes and full accelerator. Like, they'll see someone in front of them, slam the gas pedal, and then when they get too close, slam the brakes to slow down. No in between. And they don't even know they're terrible drivers since they've always driven this way.

[zahlman]

> We have apps that monitor driving and we play a tone to indicate that a hard braking event was detected. Simply letting people know that they had a hard braking event is an effective mechanism for behavior change (other companies have similar tech)

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

[infecto]

Because their definition of hard is not a slam on the pedal braking. It’s definitely out of the normal stopping but it’s not as hard as you might imagine. I could easily see people not realizing this.