[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.

[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)

[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.

[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.

[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

[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.

[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.

[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.

[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.

[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.

[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.

[dghlsakjg]

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

[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.