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.
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.
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.
All of the people tailgating are contributing to the congestion.
The train of tought goes something like this. You want to get to your destination quickly as just like everyone else and are doing everything correctly, but the assholes exploit that safety distance as a gap available for them to switch into and repeatedly forcing you to break to maintain a safe distance. Oh and the even less rational people think everyone overtaking them has stolen their rat race position.
Leaving a keeping a safe distance feels unsafe since other drivers will squeeze into it. Subjectively it feels safer to close the distance, but the numbers don't lie. Tailgating kills.
It's especially not people trying to get off the highway because then they leave and you can catch back up to where you originally were.
Putting my armchair psychoanalyst hat on: I think American society embeds a need to be the "winner", and are you winning if end up behind another driver who's contending for "your" spot?
If you've driven elsewhere for a while, you start noticing subtle driver differences, such as drivers who want to merge into your (slower) lane never braking to merge behind you and always accelerating to do so, even when you're at the tail end of a vehicle chain in your lane.
This ensures that
a) I do not cut anyone off accidentally, and minimize the amount of stress in my immediate part of the universe
b) I will (most likely) have plenty of room behind me after I change lanes, reducing chances of anyone else running up on me
c) If there's noticeable traffic, the time I spend signaling and waiting for the person to move slightly ahead of me gives plenty of warning to the people _behind_ them that I'm about to enter the lane.
Ultimately, yes, of course in principle you're right, when I change lanes, I enter the lane in front of someone.... but I _can_ control whether I enter as far as possible ahead of them.
It doesn't even have to be real. There's huge room for miscommunication. Unpredictable movements and perceived aggression, or unwillingness to be considerate to other drivers on the road, there's a whole wealth of information being processed, regardless of how little is actually real.
Now add the total lack of accountability for the driver's emotional state (don't you love yelling at other drivers, completely free of judgement?), and you can see how things spiral into road rage so relatively easily, even if everyone involved is normally a pretty chill, rational person.
If you're tailgating or brake-checking, or being inattentive and sloppy, you're basically threatening people's lives with a few tons of high speed metal, even if you don't intend that at all.
Ideally, the rules of the road are meant to reinforce a mutual understanding of the game being played. Behavior occurring when expected, proper signaling, observing limits, and making the effort to communicate where possible is a signal that you and the other driver are both operating by the same set of rules, giving you both confidence that neither of you are going to be a danger.
I've seen little "cute" exceptions where locals develop a subculture of dangerous assumptions and then get aggravated when someone from out of town doesn't immediately get it. There are other areas where aggression and what amounts to flagrant disrespect are the norm, so you've always gotta be adaptive, but ideally you get people conspicuously following the same set of rules as a sort of game theoretic optimal strategy for driving.
It's almost as if the purpose of the system is what it does.
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.
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.
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.
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.
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.
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.
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?
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.
As far as I can tell it's pure selfishness and competitiveness. Their desire isn't to cooperate and arrive it's to take from others for their own gain.
Also "Only pass in the left lane" only makes sense when the lanes aren't significantly full. The guy in the left lane wants to do 90mph but the average speed of traffic is <55mph. Should I move over just because I'm doing 55 (despite wanting to do 65) and they want to do 90? They can only do 90 if there's a cascading group of drivers in front of them who defer their own desires to the desire of the most aggressive. Seems obvious to me that moving over to let them pass is not the right move.
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.
The 401 is my favourite with eighteen lanes, four for the inner express lanes, and five for the collector lanes.
https://en.wikipedia.org/wiki/Ontario_Highway_401#/media/Fil...
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.
#trustmebro
#science
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.
A slight increase in average speed really only makes a significant difference over long drives. (5 mph increase over a 10 hour drive can cut off 50 minutes).
Otherwise we are talking about small differences in efficiency.
(I would be very open to another opinion here.).
My opinions are formed by nearly ~2 million miles driven at this point, two different driving courses, and the motorcycle safety course.
One thing I truly think that’s overlooked is how reduced road noise in the vehicle cabin can both reduce driver fatigue, but also frustration in traffic.
I 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.
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.
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.
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.
I just put adaptive cruise control on max distance and call it a day, gives me 4/5s to react, and also it starts beeping hard if intervention is required.
It has saved my bacon a couple of times.
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.
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.
People only take your lane if you are in the fastest lane. If you are in any slower lane, people tend to jump in and then leave and I have no problem with people who do that.
You can also keep a gap in the fastest lane but you need to keep track of other cars on the road. You’ll observe that most cars rarely leave their lane. People who tend to leave their lane keep smaller gaps in front of them. Use that knowledge. There are many more factors than just that but if you start observing everyone drive, your little simulation in your head will start putting other drivers into buckets.
I had a slow realization that I could just let people jump in. My goal is to maintain a constant speed and never have to hit the brakes, and I can usually still do that regardless of whether people jump line.
But yes, the principle of it is incredibly aggravating ("that space is for safety, not YOU, green Acura!!!") but I actually kinda like the practice of trying to be zen about it. I mostly get through a long trip at the same rate :)
I looked up an image catalog, and it seems that if an Acura's going to be green, it is likely to be an NS-X, which are fairly exotic as Acuras go.
I owned a black Integra for a while. If any had been green in those days, I would've definitely noticed! And, I definitely would've yielded the right-of-way to them, just so I could gawk and stare!
Usually if you maintain the slightly slower speed you had to maintain a safe following distance it doesn't matter, as the distance will either increase or they'll leave for another lane. You have to get used to drivers doing messy things in front of you, but at a safe distance. When doing this you are in fact helping the traffic becoming more fluid.
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.
It’s not hard to do. It’s only frustrating if you let it be. It really barely slows you down at all.
Really? All you have to do is lift your right foot very gently until you have the expected spacing again, no need to sudden changes of speed and if you have traffic aware cruise control it will be done for you. My old Tesla S does it pretty well. I keep it set to three second spacing and when someone cuts in front my car just gently slows down until the spacing is correct again; it doesn't brake unless the car that cuts in is very close.
For the sake of argument, assume you follow the "three second rule" and that the other driver is slightly aggressive and enters closer to the front of your safety buffer. You are now down to a two second safety buffer so rebuilding it back to three seconds costs you an extra second of travel time.
In practice this happens to me about a dozen times a day. It sometimes feels frustrating, as if each of these drivers is stealing another second I could have been playing with my kids! But ultimately it's worth spending the extra seconds to slightly increase the odds that I arrive home each day to play with them at all.
E.g.
- Switzerland and (somewhat surprisingly) UK: pretty good, people doing idiotic shit is rare enough that I'll usually comment on it if there's another person is in the car. If someone is riding my ass I'll make the effort to try and shake them off.
- Italy and Spain: horrifying, impossible to relax at all on the highway, having someone 2 car lengths off your rear bumper is the default condition.
- France and USA: somewhere in the middle where there are a lot of idiots but they are still the minority.
Subjectively, the USA feels much more sketchy because the rules are so much looser around overtaking.
This diagram changed how I think about following distance: https://entropicthoughts.com/keep-a-safe-following-distance
When the characteristics meet (when the lines overlap), you get a shock wave. Or, in the current context, a traffic collision.
Just a few of these was enough that my "discount" was only a few dollars. I regret giving Progressive my driving data.
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.
What will happen if there's some oil spill or brake failure at the point you think you should break hard?
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.
The incentives just don't line up.
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?
It also shows how close you are to the car Infront in "car length" units with a nice big indicator and the adaptive cruse control will follow that distance mostly on its own between 30-100mph
(the irony of looking at a meter on the dash to duplicate a piece of information I should be very clearly seeing out of the windscreen was not lost on me, though)
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.
Instead of pretending to shift responsibility to the car, how about people do training every so often instead? Maybe every ten years for an hour or two.
The amount of work a young person has to do here to be able to obtain a "full license" takes literal years and multiple tests.
But then nothing for the rest of their life despite advances in technology (in and out of the car) and changed traffic conditions...
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.
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.
I am so glad it hasn't. Data point of one, but gamification now has the opposite effect on me: it's such a well-worn pattern that it just annoys me. It was great when it was novel. I wonder how many others feel the same but without sampling it's hard to know.
I 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.
Unless it’s in Netherlands, where it’s 100%.
[0] https://www.npr.org/2018/06/12/619109741/clicker-training-fo...
1) Maintain a safe distances so you touch the brake as little as possible
2) Follow so close to the other car that you draft behind them (not recommended!)
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.
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!
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.
At the same time, passing on regular intercity road can have the risk reduced (up to a point) by making the passing quicker, by spending less time in the oncoming traffic lane ("aggressive passing"). It certainly does not help with comfort, though.
So perhaps your cousin is a very attentive driver who drives aggressively? That might still only make him an "average" driver (I've had such drivers almost get others in an accident in front of me), but I think it's a balance that needs to be struck, otherwise most would tune out and not be ready for emergencies.
This always stuck with me
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.
Best trick for managing this is to "drive through" the car in front of you. That is, judge your following distance based not on the car in front of you, but on the car in front of THEM.
And you don't have to "drive through" all the way down the road - it only takes one car/one level of abstraction for this approach to yield really great benefits, try it if you don't believe me.
She said the only time that the data and the rates do not match is after an accident. After an accident, the rates go up, however drivers are more careful and are statistically less likely to have an accident.
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.
Calling that person an idiot for your misunderstanding is not cool.
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.
This perfectly illustrates this broken mental model that leads to endless frustration.
Unless you put the car in reverse, you are still making forward progress. If someone merges in front of you at 30mph then you traveled hundreds of feet towards your destination in the time it took them to do that. Chill out.
- 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.
Why was their license not canceled beforehand?
Did they not get caught? If so, why? Likely other drivers have noticed the bad driving behavior. If so, why did they not report it? If they did report it, did the reports get ignored? Is there even a system and process in place for such reporting?
If they got caught, was there hesitation to revoke their license? If so, why? A potential factor would be driving in an area where you have to drive to get anywhere, which is common in the US. Why has it not been addressed that you have to drive, even if your driving habits are bad?
If bad driving behavior is too hard to punish, why? If regulations do not allow adequate punishment of bad driving behavior, why have these regulations not been changed? If evidence is missing, what evidence would that be, and how could it be collected?
If the driver was drunk, what would have been the alternative to driving? Is there adequate public transportation for drunks to get home? "adequate" depends on the drinking culture in the area where that happened.
If the driver was untrained, why were they allowed to drive? You wrote about canceling their license, so they did get a license. How was that possible without training? Does the process for handing out licenses have to be changed? Is frequent re-training necessary (more data is needed for that; if that data isn't avilable, why not?)
Obligatory link to the CAST handbook in case you want to follow that line of thinking: http://sunnyday.mit.edu/CAST-Handbook.pdf
"Crash" not "accident":
What I would really like in a car is not only my current speed, but the relative speed to the car ahead of me. Given my car has cameras and other sensors for cruise control and other features this ought to already be possible.
This is the natural response of tapping the brakes for any slowdown: people naturally over compensating and chain reactions happening behind them. This video shows how stop and go traffic forms and snowballs with no real impetus beyond mis estimated follow distance.
I always pull away at the same speed as the car in front of me and maintain the same distance as when we were stopped. It is very easy to do and completely eliminates traffic build up if multiple people do it at the same time.
This is the same reason that we have amber lights on traffic lights, so that the drivers have time to get into gear and start pulling away so that when the light goes green they are imediately travelling through it, causing no excess traffic build up at the lights. Again unfortunately people dont concentrate when they are stopped at lights and so you have the situation where they see the light go green and then proceed to start changing into gear and remove the handbrake. By the time they are moving through the green light, they have already taken 10-20 seconds of green light time, eating well into the time alotted for cars to be travelling across the junction.
The only thing which will solve this is driverless cars, meaning that the cars can all talk to each other and move at the same time like a chain. I welcome this advancement to elimante human error in driving and get rid of traffic jams for good.
If drivers are using a 2 second following distance, commonly taught in driving school, then max throughput is simply
1 car / 2 sec
This assumption is untrue at very low speeds, particularly when it takes longer than 2 seconds for a car to pass a point. For instance if we assume cars are 4m long, then with an interval of 2 seconds the cars would be touching at 4.47mph
The assumption is also untrue at very high speeds. You'll want a larger gap. That's partly because at such high speeds the ability of a vehicle to decelerate differs - if a vehicle with good brakes does an emergency stop and the car behind it has a respectable 2 second gap but has worse brakes then they can end up colliding. It's also partly because a 2 second gap at very high speeds means the car in front is further away, and that can cause a greater delay before the driver realises what is happening. As a third reason a greater margin needs to be used at very high speeds simply because the consequences of a crash are that much greater and should therefore be avoided even more than at lower speeds.
Therefore there is a kind of U-shaped curve in the "safe" following interval, and consequently a speed at which safe throughput is maximised.
That's why variable speed limits have been introduced in various places. For instance, in the UK which normally has a 70mph speed limit on motorways, in very high traffic conditions this can be lowered using electronic signs to increase the safe throughput of the road. It's commonly reduced to 50mph, though it does get lowered further in sections approaching a queue of vehicles that has actually stopped.
There's also the issue of speed oscillations. With a high speed limit and vehicles following too closely, a little variation in speed in one vehicle can turn into a larger variation in the following vehicles, causing a backwards-travelling wave of braking (sometimes to an absolute halt) and speeding up again. Lowering the speed limit reduces this.
If you want 4 sec gap at higher speeds that's fine, the formula is speed-independent for throughput, not speed-independent for following distance. If you want 4 seconds at high speed then use 4 sec instead of 2 sec (i.e. 1 car/ 4 sec)
>There's also the issue of speed oscillations. With a high speed limit and vehicles following too closely, a little variation in speed in one vehicle can turn into a larger variation in the following vehicles, causing a backwards-travelling wave of braking (sometimes to an absolute halt) and speeding up again. Lowering the speed limit reduces this.
"Lowering the speed limit reduces oscillations." Exactly, that is my whole point, that (again, locally analyzed) you can ignore the waves, and instead look only at the following distance of the slowest car in the lane, to determine throughput of the road behind that car. Your idea of "lowering the speed limit" to eliminate waves is the same net effect on throughput as observing that the throughput cannot exceed that given by the longest-following car on the road.
That postulate breaks down as soon as you move away from a laminar traffic assumption and include distracted drivers, lane changes, and weather influences. Which is why the wave theory model is important to understand the propagation of perturbations and their effect on maximum throughput.
> The throughput of a (full, i.e. rush-hour) road has nothing to do with speeds of people driving, and everything to do with following distance.
And yet, in the limit case of a bumper-to-bumper situation (or, in fluid dynamics parlance, an incompressible flow), the variable determining the change in mass flow-rate is the velocity of the medium. Mimetically, we could also look at ants. To ease congestion in a bumper-to-bumper situation, they accelerate.
Also you then just leave a bigger gap in front of you for somebody to jump into, forcing you to break more and go further back to maintain your distance. This in turn just winds up the drivers behind you who end up overtaking you. All this chaos becasue you think you are helping by 'reducing compression'.
In heavy traffic I much prefer to quickly catch the car in front up and then sit stationary with my engine off. Much more efficient and less polluting than spending the whole time with your ewngine on managing gaps and braking distances at low speeds.
What? Your travel time does not get longer, and if the traffic is merely slow then this "leaving your engine running for more of the time" is nonsense. Even if it's stop and go and you have a car that kills the engine every time you come to a dead stop, that will use more gas because you're making inefficient use of the electrical system (charging and discharging the battery more than you should have to).
> Also you then just leave a bigger gap in front of you for somebody to jump into,
Sure, so as earlier you have to pay attention and not allow that.
> In heavy traffic I much prefer to quickly catch the car in front up and then sit stationary with my engine off. Much more efficient
Doubt.
And besides doubting your claim about efficiency, you're doing exactly that which most helps the pressure wave endure, and thus you're causing more delays for more people, and more people to have to brake hard, and more engine stop/start cycles, all of which means more pollution overall not less, etc.
You really have to think systemically.
What you are refering to is the well known phenomenon of traffic waves or phantom jams. The UK has all but eliminated them with variable speed limits without the need to make every leave half a mile gap between each car.
https://nationalhighways.co.uk/road-safety/variable-speed-li...
However purposely making the cars behind you break more and causing more compression further back just so that you can avoid the compression in front of you is madness.
Google is measuring where on the road most hard braking events happen.
Insurers measure who is having the most hard braking events.
Fuck all of that.
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.
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!
The cause of hard braking isn’t mutually exclusive: bad driving or bad road design.
Have a look at a few dash cam accident videos [1]. There are many maladaptive patterns of behavior, but a frequent one that the average good driver can improve on is limiting speed on two occasions: when approaching a blind spot, and when passing stopped or slow traffic.
That second one gets lots of otherwise good drivers. They seem to think that by limiting their speed vs slow/stopped traffic they'd be encouraging people to dart in front of them. Which is somewhat true. But with limited speed, that's an avoidable or less injurious accident. By gunning it past stopped traffic, you make the accident unavoidable and more serious.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Yeah, if you want to do that, it would be helpful to know whether a financial incentive is required for the effect or not.
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?
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.
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.
... How do people not notice that they are braking hard?
I'm personally someone who is less worried about "privacy" for this sort of data. But I know lots of other people feel differently.
To me, this is a great example of the "greater good" for data sharing. But it is also a great example of responsible use of data.
So much so that I would argue that google (et al) should be compelled to make the data publicly available.
They have enough money, let's make society better.
I spend most of my time in California, have lived in SoCal and NorCal, and I spend a fair chunk of time driving around Virginia. My guess is that there's something fishy with the Virginia data being reported. Because if there is anyplace on earth with an insane number of controlled access roads, it's gotta be NVA/DC metro area (or the Tri-Border Area as I like to call it).
Also, they need to either update the caption for Figure 4, or move the plots to correspond with the caption. Clearly the Virginia data is on top (or the code is wrong, which seems exceedingly unlikely).
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/
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.
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.
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.
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.
>Also, crashes are statistically rare events on arterial and local roads, so it can take years to accumulate sufficient data to establish a valid safety profile for a specific road segment.
That is exactly what this article is about.
> 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.
The most recent budget estimate is $1bn for any changes to this interchange
Static hazards deserve physical signage and/or remediation.
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.)
In unknown roads/highways I can predict hard bumps/gaps by seeing dark oil spots in the middle of each lane.
In theory, the most dangerous turns would probably have higher variance on hard braking data.
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.
I have to hope that the actuaries at the insurance company are well aware of that. Tuned correctly, the algorithm should not unfairly penalize you.
I am reminded of my mother-in-law. She has very few at fault accidents in her decades of driving. And yet she has been involved in a statistically unlikely number of major wrecks. She would say that she is a safe driver, because she is not found at fault. I think it more likely that she is an unsafe driver who creates situations where accidents are more likely to occur but in a way that will not peg her as the underlying cause. Her rates should go up. As should yours, if you are experiencing a very abnormal number of hard-braking events even though you can ascribe every one of them to something outside of your control. Because the implication is that something about your driving habit is increased risk.
Enough events should show clusters where potholes likely exist. You would think cities would love that kind of data.
"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.
PDF download: https://iase-pub.org/ojs/SERJ/article/download/215/119/726
There's even no need to get the real names! To anonymously load person's risk coefficient, it's enough to ask to log in using Google account when buying insurance.
A negative binomial regression fit on observational data cannot establish that a statistical relationship is causal.
That's not gonna be something Google would research, of course, due to next to no alignment with their interests.
Can the quantity and length of tire marks on tarmac be used as a proxy for HBEs?
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.
1. I'm on a race track or back road enjoying curves 2. Some asshole did something stupid in front of me.
I agree that hard braking is an accurate metric for road segment crash risk, but what I find upsetting is that insurance companies that use vehicle data treat /all/ hard braking equally. In reality, the risk is caused not by every person who hard brakes, but by the first person in a line of cars that hard brakes.
More on #2 above is that my observation has been MOST of the time, the braking was COMPLETELY unnecessary. Often the person hard braking that starts the chain has absolutely nothing in front of them to the horizon and is probably on their phone watching TikTok, suddenly looked up and realized they were driving and braked as a spooking reaction. This happens, observably, so often that there are active conspiracies on the Internet that the government hires people to drive like assholes to cause traffic. Obviously that's complete bunk, but my observation here is certainly not unique.
Rather than spying on everyone using our vehicle data to charge us ever more money (I've had zero at-fault accidents in nearly 30 years of driving, but my rates only go up), maybe we should enforce attentiveness on the road and start punishing those who are left-lane hogs (causing many lane changes, which are also risky), on their phone, or drunk. It's really obscene these days driving on American roads, it seems like everyone drives markedly worse since the pandemic /and/ enforcement has gone to nothing. The only time I see people get pulled over now is in speedtrap small towns.
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.
Indeed, that is the usual definition in the US for following distance. Along with a typical example of how to determine it for yourself.
We usually use the term braking distance to describe the distance that would be required to stop the car based on current conditions and speed. This is not necessarily going to be the same as the following distance.
> It would have to be further than braking distance to be at least as safe?
Other way around. Following distance can be less, because the guy you are following cannot stop instantly unless he hits an immovable object or gets into a head-on crash. If he panic stops, then as long as your car performs similarly in braking you just need to have enough distance to allow for your own reaction time.
AFAIK braking distance for most cars is around 5 seconds at highway speed. Few people routinely set their following distance that long.
Following distance is the rule that you should leave a 2 second gap in front of you. That is often less distance than the braking distance.
You should be always able to see that your braking distance is or will be clear, and that sets the maximum speed you should drive at as you approach areas with reduced visibility, like corners or the brow of a hill. You must learn braking distances for the driving test.
eventually got me to this: https://arxiv.org/abs/2409.15561 maybe interesting for someone whos privacy focused.