[HN Gopher] Hard-braking events as indicators of road segment cr...
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Hard-braking events as indicators of road segment crash risk
Author : aleyan
Score : 162 points
Date : 2026-02-09 17:09 UTC (5 hours ago)
(HTM) web link (research.google)
(TXT) w3m dump (research.google)
| harshaw wrote:
| 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)
| pavel_lishin wrote:
| 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 wrote:
| 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
| grog454 wrote:
| 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 wrote:
| 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 wrote:
| > 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 wrote:
| 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.
| sigseg1v wrote:
| 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 wrote:
| 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 wrote:
| 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.
| infecto wrote:
| People also don't realize that just because you can does
| not mean the insurance will side with you 100%.
| ip26 wrote:
| 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 wrote:
| > 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.
| thomasguide wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| pibaker wrote:
| 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 wrote:
| 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 wrote:
| If they are not found at fault then indeed there's no cost
| for their insurance company?
| AngryData wrote:
| 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 wrote:
| 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.
| SoftTalker wrote:
| There might be, if the at-fault driver is uninsured and
| you are carrying uninsured motorist coverage.
| kube-system wrote:
| 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.
| infecto wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| It is not possible to time lights that way over any
| significant distance in a multi-way fabric of traffic.
| WarmWash wrote:
| 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 wrote:
| A seasoned motorcycle rider should be unable to rip out any
| hair, due to safely wearing a helmet!
| organsnyder wrote:
| 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.
| doubled112 wrote:
| 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 wrote:
| 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 wrote:
| Same, I cycle everywhere and almost feels like I've
| developed a sixth sense for when a driver will do
| something stupid.
| kube-system wrote:
| > 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 wrote:
| 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 wrote:
| 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 wrote:
| > 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 wrote:
| 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 wrote:
| 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 wrote:
| > 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 wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| Similarly, a road that is frequently travelled by risky
| drivers is a risky road!
| kube-system wrote:
| This is part of the reason insurers include zip code in
| their risk profiles.
| rogerrogerr wrote:
| (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 wrote:
| 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 wrote:
| 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.
| Sharlin wrote:
| 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 wrote:
| 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 wrote:
| 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!
| buckle8017 wrote:
| Driving on bad roads is just as bad for insurance as a bad
| driver is.
| JimBlackwood wrote:
| 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.
| alwa wrote:
| 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 wrote:
| 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.
| munificent wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| What are these apps or devices? Where can I get one?
| infecto wrote:
| 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 wrote:
| 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 wrote:
| Your faq doesn't mention anything about location data.
| I'd like to try it, but want to know about that first.
| dghlsakjg wrote:
| A lot of people don't realize that what they consider normal
| driving is actually aggressive driving by other metrics
| ryandrake wrote:
| 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.
| drewda wrote:
| What is the actual use of this?
|
| This research team used Google's first-party location data to
| identify San Jose's Interstate 880/US 101 interchange as a site
| with statistically extreme amounts of hard braking by Android
| Auto users.
|
| But you don't need machine learning to know that... San Jose
| Mercury News readers voted that exact location as the worst
| interchange in the entire Bay Area in a 2018 reader poll [1]
|
| It's not a lack of knowledge by Caltrans or Santa Clara County's
| congestion management agency that is keeping that interchange as-
| is. Rather, it's the physical constraints of a nearby airport (so
| no room for flyovers), a nearby river (so probably no tunneling),
| and surrounding private landowners and train tracks.
|
| Leaving aside the specifics of the 880/101 interchange, the
| Google blog post suggests that they'll use this worst-case
| scenario on a limited access freeway to inform their future
| machine-learning analyses of other roads around the country,
| including ones where presumably there are also pedestrians and
| cyclists.
|
| No doubt some state departments of transportation will line up to
| buy these new "insights" from Google (forgetting that they
| actually already buy similar products from TomTom, Inrix,
| StreetLight, et al.) [2]
|
| While I genuinely see the value in data-informed decision making
| for transportation and urban planning, it's not a lack of data
| that's causing problems at this particular freeway intersection.
| This blog post is an underbaked advertisement.
|
| [1] https://www.mercurynews.com/2018/04/13/101-880-ranks-as-
| bay-...
|
| [2] https://www.tomtom.com/products/traffic-stats/
| https://inrix.com/products/ai-traffic/
| https://www.streetlightdata.com/traffic-planning/
| pixl97 wrote:
| >No doubt some state departments of transportation will line up
| to buy these new "insights" from Google (forgetting that they
| actually already buy similar products from TomTom, Inrix,
| StreetLight, et al.) [2]
|
| 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.
| drewda wrote:
| Yeah, Google and Apple do probably have much more first-party
| probe data of passenger vehicles. But it really depends on
| the type of traffic data product. For some use-cases, it's
| more than sufficient for the vendor to buy probe data from
| specific types of fleet vehicles (like work trucks).
|
| 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.
| pishpash wrote:
| It does look much more like a revenue play. The data already
| exists, but not from the conglomorates and not as uniformly
| formatted.
| amanaplanacanal wrote:
| Caltrans could lower the speed at that interchange, and use
| traffic calming to actually get people to drive slower. Good
| traffic engineering can still make a difference even with the
| existing physical limitations.
| pishpash wrote:
| Indeed why would you even need this or a poll? The crash
| statistics already exist. What's the purpose of a proxy
| predictor unless the label is something too low signal to
| detect but may become a big issue later. The only such case is
| a new road that recently opened.
| pishpash wrote:
| On the interchange in question, they can always redo how the
| merge is designed in the same space. There is no excuse for
| that.
| jeffbee wrote:
| Absolutely nothing in this research suggests machine learning.
| All this is saying is that the hard braking events are
| associated with dangerous road segments that are well-known by
| other measures (in this case, reported crash rates).
| csours wrote:
| Actual use: autonomous vehicles know to be "more careful" here,
| perhaps to do "Jersey left" turns - right turn and U-Turn or
| other risk compensation strategies.
|
| 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.
| unbalancedevh wrote:
| > What is the actual use of this?
|
| 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.
| leetrout wrote:
| Not surprising but it is nice to have these data streams to
| explore locations that could potentially be remediated. I think
| anyone who drives interstates in metro areas would agree
| cloverleaf interchange are generally terrible with any
| significant traffic. Add in the general proclivity to drive much
| higher than the posted speed limit and these become dangerous due
| to the speed differentials and we've known this for 50 years.
|
| "A 1974 study by Hall and Dickinson showed that speed differences
| contributed to crashes, primarily rear end and lane change
| collisions"
|
| Hall, J. W. and L. V. Dickinson. An Operational Evaluation of
| Truck Speeds on Interstate Highways, Department of Civil
| Engineering, University of Maryland, February, 1974.
| engelo_b wrote:
| this google research is a fascinating pivot from the usual
| driver-centric data we look at in insurance risk modeling.
| usually we use hard braking as a proxy for how safe an individual
| driver is. but using it to identify specific road segments or
| intersections with bad geometry is huge. it basically flips the
| script from individual liability to infrastructure-level risk
| assessment.
| infecto wrote:
| This is definitely pie in the sky but I dream of a future where
| you have so many autonomous vehicles all the road that we can
| not only collect this data but also incentivize the slow
| turning wheels of government to fix it.
| engelo_b wrote:
| yeah the interesting part is that the carriers already have
| most of this data from telematics apps, it's just sitting in
| corporate silos.
|
| 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.
| pishpash wrote:
| Ok but where is the public Maps overlay for this? Is it
| available?
| engelo_b wrote:
| i'd love to see a safety heatmap layer, but the legal hurdles
| are probably massive. the second google puts a high risk
| badge on a specific road segment they open themselves up to
| lawsuits from local businesses or property owners claiming
| the algorithm is nuking their traffic or property value. it's
| probably going to stay in the hands of traffic engineers and
| underwriters for a long time.
| jeffbee wrote:
| Google is offering this as part of the geospatial platform
| that they market to governments for huge $$$ so I don't think
| you are going to get it for free any time soon. Maybe limited
| access if you have an Earth Engine developer account?
| chaps wrote:
| Like another poster said, this is very well known already. It's
| one of the reasons why municipalities purchase this data from
| data brokers.
| presidentender wrote:
| I got one of those dongles from my insurance company that plugged
| into the ODB2 port and reported my driving habits.
|
| I was a bad driver. It would frequently beep at me to let me know
| that I had braked too hard. I was mystified. "What should I have
| done differently," I'd think, as I raged at the objective machine
| that judged me so.
|
| The next time my brother came to visit, he called mom. "Oh, and
| presidentender is a good driver now." I didn't put the pieces
| together right away, but it turned out that the dongle had
| actually trained me, like a dog's shock collar.
|
| The reason for my too-frequent hard-braking events wasn't speed,
| although that would be a contributing factor. It was a lack of
| appropriate following distance. Because I'd follow the drivers in
| front of me too closely I'd have to brake hard if they did... Or
| if they drive normally and happened to have a turn coming up.
|
| Over the period I had the insurance spy box in my truck I learned
| without thinking about it to increase my following distance,
| which meant that riding with me as a passenger was more
| comfortable and it beeped less often. Of course since I'd been so
| naughty early during the evaluation they didn't decrease my
| rates, but I think the training probably did make me
| statistically less likely to crash.
| xnx wrote:
| Thanks for sharing. I'm genuinely impressed to hear someone
| publicly share a story of growing self awareness and
| improvement.
| socalgal2 wrote:
| I'm always surprised at the number of people that follow too
| closely.
|
| This always stuck with me
|
| https://www.youtube.com/watch?v=iJFOTSYJrtw&t=466s
| HoldOnAMinute wrote:
| Is there any vehicle that uses it's sensors to make a gentle
| suggestion about following distance?
|
| 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?
| SoftTalker wrote:
| A lot of them do. My wife's VW beeps an alert if you're too
| close to the car ahead of you. It might be that it only
| activates above a certain speed.
|
| 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.
| ARandomerDude wrote:
| > Why hasn't gamification of safe driving habits been built
| directly into the car itself before now?
|
| 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.
| yial wrote:
| I concur with you regarding gamification. When I am aware
| of the gamification it fills me with exhaustion to
| annoyance to extreme frustration. This is especially true
| of things that I want to use for one purpose.
|
| 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.
| ErroneousBosh wrote:
| I drove one of our Kia Niro EVs that we have at work
| recently, and it started warning me to take a break about
| fifteen minutes into the drive.
|
| 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.
| dietr1ch wrote:
| One of the few things I really don't like about my Subbie is
| that it tries to help braking.
|
| 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.
| rconti wrote:
| Is it one of those cars that alters the brake boost
| depending on circumstances?
|
| 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.
| vablings wrote:
| My wife's VW will show the following distance and if you are
| too close a small icon is displayed on the dash. I believe
| its warning you that if there is emergency breaking required
| for the car it will not be able to stop in time.
|
| 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
| girvo wrote:
| My Cupra Born does this; it has a little line that it draws
| on a "road" with the car in front, and you have to put the
| car in front of the line to be safe. Its quite a fun little
| system haha, works well on me!
| jjice wrote:
| I have a friend who would also follow too closely to the cars
| in front and got one of these. Her rates went up and she
| eventually got into an accident (no injuries to anyone) because
| she would follow too closely and still break too hard.
|
| Now she still has the machine, still follows too closely, and
| still breaks too hard in her new car...
|
| Good it worked for you though!
| yial wrote:
| A cousin of mine is abysmal to drive with as a passenger. He
| follows too closely to the car in front of him, regardless of
| lane / speed. He will slow down, follow closely, and then
| aggressively pass. Repeating ad nauseam.
|
| No smooth maintaining of speed and nice passes as able
| without slowing down.
|
| Surprisingly, his accidents have mostly seemed to involve gas
| pumps, barriers, and other obstacles at low speed.
| toxik wrote:
| This is left lane driving policy. I am like this, and I was
| not at first. What makes you drive like this is rush hour
| traffic. "Move up the lane or move out of the lane" is the
| sentiment, basically. As others have noted, it is
| essentially an adversarial process. If you drive nice,
| people cut in front and you're unable to drive nice to both
| those behind you and in front.
| sagarm wrote:
| Letting them "cut in front" is good driving.
| mountain_peak wrote:
| Maintaining a safe following distance is incredibly challenging
| on busy freeways where hard braking is often 'required'. Most
| people have likely found themselves in this situation: vehicle
| changes lanes in front of you; 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.
|
| 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.
| amanaplanacanal wrote:
| Does it really matter though? Is the end result just a couple
| of minutes later in a 30 minute commute? Or does it actually
| make a large difference in travel time?
| mountain_peak wrote:
| It used to be more of an issue when I was younger. Now that
| I'm older and more 'seasoned' (plus reflexes do slow down),
| I'm far more patient and have no issue maintaining a
| healthy following distance. I think the statistics reflect
| this in age vs. accident rate as well.
|
| 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.
| Noumenon72 wrote:
| For your commute to take 4/3 the time, you would have to
| be averaging 3/4 the speed -- going 45 in a 60. That
| doesn't make sense because even going 55 would mean
| traffic pulled away from you rather than you having to
| drop back from it. Going 55/60ths the speed means you
| arrive in 60/55ths the time, or an extra 4 minutes on a
| 45 minute commute.
| yial wrote:
| It doesn't - but people don't necessarily make rational
| choices regarding speed and driving. There's a tendency to
| de personalize other drivers.
|
| 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.
| badc0ffee wrote:
| > (5 mph increase over a 10 hour drive can cut off 50
| minutes)
|
| 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.
| yial wrote:
| I would argue I can still say it /can/ cut off 50
| minutes.
|
| 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. )
| alexose wrote:
| > A slight increase in average speed really only makes a
| significant difference over long drives.
|
| 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...
| avidiax wrote:
| > Is the end result just a couple of minutes later in a 30
| minute commute?
|
| 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.
| cucumber3732842 wrote:
| I have been doing the same commute at the same time for the
| better part of a decade. At this point I can look at my
| watch and tell if I'm ahead of schedule or behind schedule
| and infer what the compounding effect will be later in my
| commute.
|
| 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.
| yial wrote:
| 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.
| VladVladikoff wrote:
| 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.
| yial wrote:
| 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.
| girvo wrote:
| 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!
| fredophile wrote:
| Where I live travelling at that speed will get you passed
| by every cop and state trooper driving on the same road.
| A lot comes down to local norms and enforcement.
| its_magic wrote:
| In Alabama on the interstates and highways the rule of
| thumb is: "8 you're great, 9 you're mine."
| michaelt wrote:
| _> 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.
| bcrosby95 wrote:
| 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.
| vardalab wrote:
| 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.
| yial wrote:
| 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
| Noumenon72 wrote:
| 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.
| yial wrote:
| 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
| ).
| ChuckMcM wrote:
| Okay I'm thinking of a very Shenzen kind of gizmo for your
| car that projects a bright red laser "keep out" box on the
| road in front of your car which is adjusted in size for your
| current speed.
| NitpickLawyer wrote:
| We have something like that in eu with road markings. Both
| for clear weather and fog/rain. They mark some of the lines
| differently, and tell you how many lines you should have
| between you and the car in front. I think they were first
| trialed and then printed in several places.
| ChuckMcM wrote:
| Cool. But I'm thinking this box floats in front of your
| car on the road in real time. See you're driving and
| ahead of you on the road is this box. At night it might
| interfere with your night vision, might have to workshop
| that a bit.
| ErroneousBosh wrote:
| There's a couple of bits of motorway in England with
| that, I'm pretty sure the M6 and the M1. There are white
| chevrons painted on the road and you keep two of them
| between you and the car in front.
|
| Also "Keep Two Chevrons Apart" is going to be the name of
| my specialist Citroen breaker's yard.
| rootusrootus wrote:
| I think a lot of people would just consider that a
| challenge.
|
| On the occasion when I am towing our travel trailer, it is
| really incredible how unsafe that makes other drivers act
| around me. They will jam themselves in front of me at all
| costs, with no consideration for physics.
| daringrain32781 wrote:
| I see this happen to semi trucks on the highway. People
| interpret big open space as a place to merge. As you say,
| people have no consideration for why there might be a
| large space in front of a semi. A 50k lb+ truck hitting
| the back of a ~4k lb vehicle is not pretty.
| ChuckMcM wrote:
| See for a truck it could say "DEATH ZONE KEEP CLEAR"
| which would be accurate. Given that it's projected it
| could rotate through various languages too.
| dheera wrote:
| There was a bike light that projects a bike lane onto the
| road, not sure why they are not more popular.
| antisthenes wrote:
| Can't wait to get blinded by lasers when cars are going
| over bumps and speed humps.
|
| I know you were probably writing tongue in cheek, but that
| is one of those "solutions" that doesn't stop bad actors
| and makes good actors more miserable than usual.
| duped wrote:
| Why does this require "hard" braking? If another car cuts in
| front of you just decelerate gently. You don't brake and wait
| until the gap is big enough (also if this is stop-and-go
| traffic, you should be trying to avoid braking at all)
| mountain_peak wrote:
| My original observation wasn't worded as well as it could
| have been. I meant in situations where hard braking could
| be required on a moment's notice for no particular reason
| (e.g. Chicago freeways where everyone is doing 70 mph
| bumper-to-bumper and decreases to 10 mph all of a sudden).
|
| Indeed, when someone changes lanes in front of me, I gently
| let off the accelerator, but as someone else noticed, that
| can enrage drivers behind me (I don't take it personally),
| and I'm definitely traveling fast enough to remain in the
| middle lanes.
| sagarm wrote:
| If you think highway driving requires hard braking, you're a
| bad driver.
| appreciatorBus wrote:
| Yes. If people are constantly moving into your appropriate
| head way this is doubtless annoying but the correct
| response is allow yourself to decelerate slowly to re-open
| that space again, repeat as many times as necessary, even
| if it means a bunch of agros end up in front of you. Better
| for them to be in front where you can see them, than behind
| or to the side, were you can't.
| mlyle wrote:
| Yah. There's something that feels unjust about it -- the
| perception that the people cutting are getting something
| over on you -- that causes us to want to behave badly.
|
| 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.
| cmurf wrote:
| They are likely getting more frequent brake pad
| replacements.
|
| 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.
| its_magic wrote:
| If you added a missile launcher to your vehicle, it could
| become ritualistic combat again.
| ryandrake wrote:
| Society would have a lot fewer car accidents if we,
| collectively, could get over that "Oh no someone dared to
| _get in front of me!_ " feeling.
| bell-cot wrote:
| Or stuck on a highway with bad drivers. My local paper's
| current "bleeds => leads" story is about a head-on highway
| crash, between a big pickup truck and a wrong-way driver.
| Less that 4 hours after being posted, that story has
| already slipped off the front page.
| refulgentis wrote:
| I'm not sure the article, the article being off the front
| page now, or driving with bad drivers has anything to do
| with it.
|
| 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.
| OkayPhysicist wrote:
| "local drunk dies by misadventure" is a really, really
| boring news article.
| dekhn wrote:
| I just had to hard brake a few days ago. A driver a couple
| lanes over on 101 slammed on their breaks, rotated 90
| degrees, and came to rest across a couple lanes (one of
| which was mine). Fortunately, I was alert, driving the
| speed limit, and in the right-most lane, with nobody
| following me close. The whole thing happened in less than 5
| seconds.
| CamperBob2 wrote:
| It doesn't normally _require_ hard braking, but when
| automated emergency braking decides to slam on the brakes
| at random for no reason in my own car, everybody behind me
| will share my resulting insurance rate increase.
|
| It's almost as if the purpose of the system is what it
| does.
| BigTTYGothGF wrote:
| If you do it on the regular, or even occasionally, sure,
| but emergencies are emergencies.
| kube-system wrote:
| If you think people are going to cut in front of you, provide
| a safety cushion large enough to account for that. Aggressive
| drivers almost universally will consume the forward part of
| the space cushion you leave. At most you will simply need to
| lift the accelerator to maintain space. The only time someone
| cutting in front of you should require hard braking is if
| they also brake hard.
|
| 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.
| MostlyStable wrote:
| I'm not sure it's that negligible. Mythbusters found that
| weaving in and out of traffic could save between 5 and
| _twenty-five_ percent. Now A) Mythbusters did an experiment
| with an N of like 4 or something, along a single commute in
| the Bay Area, so it 's basically anecdote and I'd love a
| better source if one existed, but it is at the very least
| proof-by-existence that larger impacts on travel time _can_
| happen. And their non-weaving person was, if I recall from
| the video, not constantly decelerating to keep a buffer.
|
| 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.
| streetfighter64 wrote:
| 25% of time saved corresponds to increasing your average
| speed by 1/(1-0.25)=33%, for example from 45 to 60.
| cucumber3732842 wrote:
| Letting a large fraction of the freeway cut in front of you
| will turn normal drivers behind you aggressive, or at least
| aggressive enough to go around you. There's a balance to be
| struck.
| olyjohn wrote:
| [delayed]
| bluGill wrote:
| False. I've done it many times - when you open up space two
| cars jump in, but the rest don't and so the space remains.
| But you notice those two cars and think it means more than it
| does.
| OptionOfT wrote:
| > North America
|
| 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.
| gwbas1c wrote:
| I'm one of the faster drivers and I maintain a safe distance.
| (I usually have the most distance in rush hour.) It's very
| easy with adaptive cruise control or the other self-driving
| technologies that are on the market.
|
| 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?
| thewebguyd wrote:
| > and you're expected to keep up with the flow of traffic.
|
| 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.
| sershe wrote:
| The most frustrated people are those behind you, and if I was
| id soon be another person merging in front of you. If people
| are constantly merging in front of you, either everyone is
| going too fast or you are going too slow :)
| Gravityloss wrote:
| I live in a place that has harsh winter conditions with ice,
| gravel and the occasional loose tire stud flying into
| people's windshields, warranting frequent expensive
| replacements.
|
| 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.
| stevage wrote:
| Wow, I didn't know that was a thing. Been driving nearly 30
| years, and never had a windshield chip.
| its_magic wrote:
| Do you have a wood surface nearby? I would recommend
| giving it a good knock.
| its_magic wrote:
| Another trick that works is just to let the windshield get
| cracked once. Then it will be immune to further rock
| strikes.
|
| #trustmebro
| bloomingeek wrote:
| Tailgating is against the law. Tailgating causes hard
| braking.
|
| 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.
| rconti wrote:
| Even that can be tricky, with the indecisive behavior
| people use when merging.
| tadfisher wrote:
| That one's easy: leave space in front of you for those
| merging onto the highway.
|
| 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.
| HPsquared wrote:
| James May calls this "Christian motoring". Golden Rule
| etc
| dekhn wrote:
| While leaving space is nice, the person on the highway
| already typically has right-of-way.
| cucumber3732842 wrote:
| >I was never honked at, even by the crazy semi truck
| drivers.
|
| 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.
| its_magic wrote:
| In the Atlanta area I've experienced a few times people
| FLYING up on me in the right hand lane while I'm cruising
| along at a conservative, gas sipping 55 MPH in my old
| truck, blaring their horn at me like I'm some kind of
| maniac.
|
| I don't want to live on this planet anymore.
| duncangh wrote:
| Driving and living in Atlanta after living in Charleston
| and Raleigh felt like transitioning from a modern
| cooperative society to an island of cannibals. The amount
| of aggression needed to change lanes largely regardless
| of attempts to signal good faith and politeness is
| baffling. Driving is a fascinating ritual with vastly
| differing norms across regions. It would be interesting
| to learn if anthropologists have studied this
| rconti wrote:
| I find it quite easy to hold/manage a tight space that people
| won't cut into, and don't have to brake hard, because I look
| ahead.
|
| To be sure, it's more mentally taxing to hold a tight gap, so
| it's not something you want to do all the time, but it's
| fine.
| trgn wrote:
| > another car sees a gap and changes lanes in front of you.
|
| 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.
| Sohcahtoa82 wrote:
| > vehicle changes lanes in front of you;
|
| 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.
| MisterTea wrote:
| Safe following is super important. Few years back about a month
| after I bought a new car I was driving to work keeping a larger
| than normal gap thanks to a bit of "new car" anxiety. I was in
| the left lane, keeping pace with a cluster of three cars ahead
| of me, two of them tailgating. I don't know what happened but
| within seconds the middle car swerved, side swiped a car in the
| middle lane then rear ended the lead car while the trailing car
| rear ended them. Four cars smashed up right in front of me. I
| was fine because I had plenty of time to slow down and pull
| onto the shoulder to clear the chaos.
| wffurr wrote:
| Just like Lightning McQueen:
| https://www.youtube.com/watch?v=AvhFjVj7k44
| hiq wrote:
| As a passenger, I really notice the difference, and I wish more
| drivers (including professionals) would learn as you did. It
| probably saves energy as well, especially when driving in
| cities, although I guess it's marginal.
| dietr1ch wrote:
| I don't think it's marginal since accelerating the car needs
| way more energy than fighting loses due to wind and tyre
| resistance.
|
| 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.
| coredog64 wrote:
| Back when I had a Prius, I made a conscious effort to avoid
| using the brake pedal during the highway portion of my
| commute. It made a small difference to fuel economy, but
| treating it as a game reduced the frustration with stop&go
| traffic.
| daringrain32781 wrote:
| I was recently driving a friend and hit a mile-long backup at a
| freeway exit. At some point in the lineup, a car abruptly cut
| in front of me to merge into the line. The friend asked "why'd
| you let them in" - but I didn't let them in on purpose, I was
| just maintaining a reasonable following distance which people
| seem to interpret as "hey cut in here for free"
| dietr1ch wrote:
| The balance between safe following distance and letting
| people cut in varies a lot by city. Maybe he learnt to drive
| elsewhere?
|
| 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.
| bluGill wrote:
| It is called the zipper merge. You were in the wrong for
| waiting in the stophed lane and the other person right for
| passing all you thinking you are better.
| rationalist wrote:
| I'm pretty sure the other person is not talking about a
| 2-to-1 lane merge.
|
| Calling that person an idiot for your misunderstanding is
| not cool.
| johnmaguire wrote:
| On the other hand, at age 20, with very high premiums, I got
| one of these devices which never beeped except on a few too-
| short exit ramps on highways in my city. The choice on these
| exits is to slow down traffic on the highway, or endure a "hard
| stop" by braking immediately when you are on the ramp, and
| coming to a full stop at the stop sign.
|
| Just a few of these was enough that my "discount" was only a
| few dollars. I regret giving Progressive my driving data.
| ip26 wrote:
| I had a somewhat similar experience - as I recall, most beeps
| happened as a result of a few stop lights with too-short
| yellows (e.g. the light changes yellow and you, even though
| you are below the speed limit, either panic stop or run the
| red light)
|
| 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.
| marcosdumay wrote:
| If there's no extra exit lane, the right choice is to slow
| down traffic on the highway.
|
| What will happen if there's some oil spill or brake failure
| at the point you think you should break hard?
| johnmaguire wrote:
| The exit ramp is not sufficiently short as to be unable to
| stop safely, even with my old 2001 Toyota Corolla. It is
| however sufficiently short that you cannot stop without
| recording a 'hard brake' on the Progressive Snapshot
| device.
|
| 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.
| Gud wrote:
| I can only speak for Europe, but driving too closely to the
| driver in front is unfortunately how 90% of drivers drive.
|
| Unless it's in Netherlands, where it's 100%.
| dheera wrote:
| > It was a lack of appropriate following distance.
|
| Not in my case. I keep plenty of following distance, 9 times
| out of 10 my hard braking is because some idiot cuts into that
| following distance and brake-checks me.
| darkteflon wrote:
| People here in Tokyo follow at obscenely tight distance on the
| freeways and motorways. Drives me crazy. Don't have the data,
| but having driven here for over 20 years, I'd venture that
| short following distances must be one of the main causes of
| accidents on these types of roads. People are otherwise
| generally cautious and attentive drivers. When I've expressed
| frustration about it to locals in the past, the response is
| often "but if you leave more space, people will cut in!" To
| which I respond, "okay, and?!" I feel like a single big media
| campaign to improve following distances could result in a big
| improvement. So frustrating.
| camel_gopher wrote:
| The problem with increasing your following distance though is
| now you get other drivers cutting in, and you're back to where
| you started
| bluGill wrote:
| Only two, then people who maintain their lane are there and
| there is space.
| MeteorMarc wrote:
| If you have to brake hard, it is still important to not brake
| harder than necessary, to give the cars behind you the best
| possible chance to react in time.
| iamflimflam1 wrote:
| As one of my friends put it - driving in the US is like being
| in Whacky Races.
| SLWW wrote:
| While i find everything about this post thoroughly dystopian; I
| will state that I don't break harshly, just about ever, my car
| still has it's original breakpads (they still have some life,
| about a cm and a half to two) and it had 107k on the odo. Never
| been in an accident outside of getting break-checked by an
| insurance scammer when I was 19, and a head on when i was
| stopped at a stop sign.
|
| Although I keep a varying follow distance, if there is an open
| lane immediately adjacent to me, I don't care if i'm tailing
| someone a bit, but if I'm boxed then you better believe it's 6+
| car distance.
| kqr wrote:
| Not only are you less likely to crash -- you're less likely to
| cause a crash ten cars behind you.
|
| This diagram changed how I think about following distance:
| https://entropicthoughts.com/keep-a-safe-following-distance
| taeric wrote:
| Kudos on you for acknowledging that your behavior changed! It
| is depressing how many people online are convinced that the
| emergency braking systems are too aggressive. The best is the
| cohort that insist these systems will be what causes accidents.
| dmix wrote:
| My only ticket and accident I've been in was because an Uber
| SUV hard braked at the end of a highway offramp at night time
| when the light was green, the car in front of me hit it, then I
| hit that car despite braking hard + my cars autobreaking radar.
| I was charged with following too close even though I didn't
| cause the accident. Damaged the car pretty badly. There was
| also a pregnant lady in the Uber that caused it.
| Someone1234 wrote:
| This type of research is highly valuable but too rare; this is
| generally because of how we view Road Accidents at a core level:
|
| - Road Accidents: "A driver caused this, let's determine who, and
| find them at fault."
|
| - With Air Accidents: "The system caused this, let's determine
| which elements came together that ultimately lead to this event."
|
| The first is essentially simplifying a complex series of events
| into something black and white. Easy to digest. We'll then keep
| doing it over and over again because we never changed the
| circumstances.
|
| The second approach is holistic, for example even if the pilot
| made a mistake, why did they make a mistake, and what can we do
| to prevent that mistake (e.g. training, culture, etc)? But maybe
| other elements also played a part like mechanical, software,
| airport lightning, communications, etc.
|
| I bet everyone reading this knows of a road near them that is an
| accident hotspot and I bet they can explain WHY it is. I
| certainly do/can, and I see cops with crashed cars there on a
| weekly basis. Zero changes have been made to the conditions.
| rootusrootus wrote:
| An issue of volume, I would guess. If my quickly gathered stats
| are accurate, there are on the order of 100K commercial flights
| every day, and 1B drives. So road accidents are expected to be
| more numerous, and they usually have less impact than an
| airliner going down. Also - the NTSB _does_ indeed investigate
| car accidents on occasion, and when they do, they definitely
| include systemic analysis.
| trgn wrote:
| much easier too investigate and solve though. a few lines of
| paint here, a bollard there.
| cbruns wrote:
| How long until my insurance company can figure out my commute
| route and adjust my rates based on the collective risk of the
| segments?
| HoldOnAMinute wrote:
| Or it could suggest a less risky route and offer you a discount
| in exchange for taking that route instead.
| pishpash wrote:
| Why can't Gooapple suggest this today?
| olliepro wrote:
| There's a section of I-15 in Utah's Salt Lake County which
| reliably has a crash on weekdays at 6pm. It was unfortunately at
| a pinch point in the mountains with no good alternate route...
| very annoying.
|
| In a similar way that Google Maps shows eco routes, it'd be fun
| for them to show "safest" routes which avoid areas with common
| crashes. (Not always possible, but valuable knowledge when it
| is.)
| barbazoo wrote:
| When we worked at a p2p car sharing company it was well
| understood what a treasure trove that past accelerometer data was
| as good input to frequency prediction of a claim resulting from a
| particular rental.
| OneOffAsk wrote:
| Aim to make the road laminar. Every time you hard brake, you're
| causing the milk jug to glug, making a ripple of entropy as
| momentum turns to heat from your brakes and those behind you,
| sometimes in perpetuity. I learned this while doing a 1.5hr daily
| commute in a Subaru with a clapped out manual transmission. I
| wanted to conserve energy shifting, but realized I was now
| participating in large choreographed dance of "smooth" with other
| drivers who already knew this. There are many of us. And we all
| glare at the driver blinking their red lights on the interstate
| indicating that they're loud and proud of introducing turbulence
| to an otherwise peaceful system.
| delichon wrote:
| I'd love to have a danger heat map displayed on a HUD while
| driving. Say a default green banner that goes red near a hot spot
| or even animates near a current hazard. Mostly it could use these
| same stats, but then be strident if anything unpredictable is
| detected nearby.
| stevage wrote:
| Me too, that's a great idea. Or just incorporated into the
| satnav, better than getting the warning for an upcoming speed
| camera.
| benlivengood wrote:
| I'm really curious what their data looks like at the various
| racetracks and circuits. Fun fact; most raceways have accurate
| street-level indicators (including that they are one-way, but
| sadly they are not the best racing line) on most online maps, and
| my car did complain to me in its weekly report about a lot of
| hard turns, quick acceleration, and hard braking with helpful
| pins on e.g. Laguna Seca or Thunderhill corners.
|
| In theory, the most dangerous turns would probably have higher
| variance on hard braking data.
| roflchoppa wrote:
| Dude the fucking 101S/808S connector is atrocious on so many
| levels.
| adrianmonk wrote:
| OK, now that you have this data, give me a "prefer safer routes"
| option in Google Maps navigation!
|
| While you're at it, give me an option to avoid unprotected left
| turns and to avoid making a left turn across a busy road where
| cross traffic does not stop. (But only during heavy traffic; it's
| fine when nobody is on the road.) Not only are these more
| dangerous, they're also more stressful and they also introduce
| annoying variation into my travel time.
| stevage wrote:
| I think Lyft already does this for their driver navigation.
| kazinator wrote:
| Hard braking could be detected externally; you can tell when
| vehicles are braking hard from the deceleration and suspension
| effects, without any surveillance equipment installed in them.
|
| That's not gonna be something Google would research, of course,
| due to next to no alignment with their interests.
| rconti wrote:
| This is a great use of this technology. In aggregate, these hard
| braking events _do_ tell us about road design issues. They also
| tell us about problematic drivers, in aggregate.
|
| I'll never use one of these dongles, though, because I don't want
| my every move second-guessed. There's nothing _inherently_
| dangerous about isolated hard braking or cornering or
| acceleration events. It all depends on context. Am I braking hard
| to avoid an obstacle or mistake by another driver? Is there
| someone behind me that's likely to rear-end me, or am I in the
| middle of a highway in the desert? Did I just replace my brake
| pads and I'm bedding in the new pads?
|
| I don't want to have to worry about whether I've used up my
| invisible quota before the algorithm decides I should be moved
| into a more expensive insurance bracket.
| oxag3n wrote:
| Too bad there's no map with such indicators, I'd definitely use
| it for my route planning, especially in unknown area. I usually
| know pretty well dangerous parts if I drive there frequently.
|
| In unknown roads/highways I can predict hard bumps/gaps by seeing
| dark oil spots in the middle of each lane.
| jmkd wrote:
| Against inferential statistics: https://hdl.handle.net/2381/37564
|
| PDF download: https://iase-
| pub.org/ojs/SERJ/article/download/215/119/726
| BurningFrog wrote:
| I for one am very glad manual driving is being phased out!
| luxpir wrote:
| Wait, what do they teach in North America? Never heard the term
| "following distance" before now. Sounds misleading.
|
| In Britain at least we call it "braking distance" and you're
| supposed to leave 2 seconds at least between you and the person
| in front. Count it off a lamp post/sign etc.
|
| In certain at-risk areas they use chevrons on the road and signs
| telling you to keep at least 2 chevrons between you and the car
| in front.
|
| People definitely always get into my braking distance in slower
| moving traffic, so that happens here too of course. But when
| things are moving well I likely push the limit and am generally
| moving faster than most others: going by GPS speed vs speedo,
| pushing a little into the discretionary and unofficial +10%
| guidance etc. And weirdly enough I do this for safety and fuel
| economy.
|
| I generally prefer to avoid other vehicles as much as possible in
| all situations. But I was a motorbike rider in my youth. Once a
| defensive driver...
|
| From that perspective, following distance sounds way more like a
| gap I want to close up than braking distance does.
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