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Nice research. This is fairly well known in insurance circles. Most auto insurers that do telematics consider hard braking the strongest indicator of risk. On

• pavel_lishin 8mo ago
  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 8mo ago
    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 https://www.youtube.com/@IdiotsInCars1
    • grog454 8mo ago
      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 8mo ago
        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 8mo ago
          > 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 8mo ago
            I assume you are referring to this video: https://www.youtube.com/watch?v=sEpHyMtDcPY 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.
    • sigseg1v 8mo ago
      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 8mo ago
        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 8mo ago
          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 8mo ago
            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.
            • IanCal 8mo ago
              I think you’re misunderstanding, the person pulling in front is not giving you seconds to make space - they are deliberately trying to crash into you.
      • 8mo ago
    • thomasguide 8mo ago
      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.
      • maest 8mo ago
        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.
      • michaelcampbell 8mo ago
        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.
    • geocrasher 8mo ago
      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 8mo ago
        >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
    • pibaker 8mo ago
      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.
  • kube-system 8mo ago
    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 8mo ago
      If they are not found at fault then indeed there's no cost for their insurance company?
      • AngryData 8mo ago
        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 8mo ago
          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 8mo ago
            "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.
      • 8mo ago
  • infecto 8mo ago
    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 8mo ago
      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 8mo ago
        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 8mo ago
        It is not possible to time lights that way over any significant distance in a multi-way fabric of traffic.
  • WarmWash 8mo ago
    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.
    • RupertSalt 8mo ago
      A seasoned motorcycle rider should be unable to rip out any hair, due to safely wearing a helmet!
      • Mawr 8mo ago
        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.
    • organsnyder 8mo ago
      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 8mo ago
        If you cycle and it doesn't make you a better driver (and pedestrian) you're probably a bad driver and a bad cyclist.
    • doubled112 8mo ago
      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.
• kube-system 8mo ago
  > 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 8mo ago
    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
  • bluGill 8mo ago
    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 8mo ago
      > 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.
  • dghlsakjg 8mo ago
    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.
  • mpyne 8mo ago
    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.
• zahlman 8mo ago
  > 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 8mo ago
    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.
• advisedwang 8mo ago
  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.
  • alex43578 8mo ago
    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 8mo ago
      Similarly, a road that is frequently travelled by risky drivers is a risky road!
      • kube-system 8mo ago
        This is part of the reason insurers include zip code in their risk profiles.
  • rogerrogerr 8mo ago
    (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 8mo ago
      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.
• alwa 8mo ago
  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 8mo ago
    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 8mo ago
    > 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 8mo ago
  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 8mo ago
    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 8mo ago
      that is fascinating
  • infecto 8mo ago
    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 8mo ago
      What are these apps or devices? Where can I get one?
      • infecto 8mo ago
        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.
        • 8mo ago