Time lost by driving fast | Hacker News Reader

Time lost by driving fast

ncbi.nlm.nih.gov

67 pointsshawndumas61 comments

I like the assumption implicit in this study: time spent driving is equivalent to the time spent dead.

The assumption is actually that you'd prefer to spend extra time driving than to correspondingly lower your life expectancy.

They may have taken this into account, but the worse equivalency in my mind is that a second saved today is equivalent to a second decades from now at the end of my life expectancy. It seems like even a conservative discount rate would completely eliminate any perceived time loss.

Computing the discount rate in light of the probability of the singularity or skynet is left as an exercise for the reader.

Not necessarily; I often listen to audiobooks and the like while driving, or sometimes I value it as time to think. I've even consumed several dozen college lectures via MIT and UC Berkeley podcasts.

I find when an audio-book is truly engaging that I don't realize I just drove 20 miles which probably means I wasn't paying as much attention to the road as I should have.

Ah, one of my favourite correlation/causation mix-ups. Proving that increased speed is associated with an increased accident rate is not the same as proving that accidents are caused by speeding (and therefore 'accident rate could be reduced by slowing down').

Personally, I'm more inclined to think that dangerous drivers tend to speed more than safe drivers, hence the correlation, but in any case I'd love to see some evidence either way.

It's not clear whether this applies to urban speeding or highway speeding.

Urban speeding does increase accidents because of the large number of unexpected events in an urban setting (pedestrians, cars driving into intersections, etc).

But the main issue I have with speed limit studies is that seem to make this underlying assumption that everyone follows them. If the core group of accident-causing people drive fast/drunk/etc regardless of the rules, then lowering limits/changing rules must have limited effect.

Underlying all this is the government love of speeding taxes. The only problem is, the marginal return on speeding tax decreases as the tax take goes up. Because people decide to obey the limit, the tax take starts to go down. Thus the conundrum for governments - do they set the fines at a level where people are annoyed but don't mind, or do they increase the fines to the point where revenue steeply drops.

Two very good points. I speed like crazy on an open highway when on my motorcycle, but I accelerate very slow and stick to the speed limit when in the city. Too many bicyclists and pedestrians, not to mention intersections. Speeding on an empty and straight freeway has considerably less consequence.

I definitely agree that the worst 20% of drivers create 80% of accidents (made up numbers), which makes most any speed limit conversation null and void.

Yes, particularly in light of recent articles I've read describing improved safety as a result of increasing potential confusion (removing lane markers, etc.). The theory is that forcing people to pay attention, well, makes them pay more attention.

I'd like to add another possibility beyond what you've noted. Might it be that speed isn't itself more dangerous in that it "causes" accidents, but when an accident occurs and higher velocity is involved, that means more kinetic energy is to be dissipated, and with all that energy in play, the results may be more dire?

I'd also like to see more variables factored out of the data. I'd like to know about someone (like me) who observes other safety rules like seatbelts, proper lane discipline including signaling, safe following distances, etc.

The theory is that forcing people to pay attention, well, makes them pay more attention.

It seems to me that faster speeds may also force people to pay more attention, as each driving decision occurs in a shorter timespan.

As for urban/suburban speeding, the risk factors (pedestrians, children, intersections) are completely different, and increased speeds would clearly increase risk, as well as slow overall traffic flow as fewer cars could successfully turn onto fast-moving streets.

Well, it's a simplification of a very complex system. I can think of at least one intersection where even going 40mph in a 35 zone will at least double your risk of a crash.

I can think of other situations, for example highway driving, where going 80mph in a 65mph zone probably has an only minor effect compared to going 65mph, and depending on traffic could be safer.

I pretty much stopped caring after "computer model". I find it very hard to believe the putative results are above the noise threshold of errors in the model. In fact the cynic in me finds itself a little surprised that that's the best result they managed to gussy up after fiddling with their model's parameters. I also can't help but think that they could kiss further funding goodbye if they reported that driving faster is better.

>>I also can't help but think that they could kiss further funding goodbye if they reported that driving faster is better.

So true...

This seems akin to economists claiming that a 10% chance at $10,000,000 is just as good as a guaranteed $1,000,000 because on average you end up with the same amount of money.

Although it's technically true, any given person is better off choosing the more certain result.

that's my initial gut reaction. Though I should add that my gut reaction has a fairly low success ratio when it comes to statistics.

My problem was the conclusion: "As a nation, drivers in the United States travel slightly too fast and could improve overall life expectancy by decreasing their average speed slightly."

As a nation, drivers in the United States travel at pretty much the average speed. (See: http://en.wikipedia.org/wiki/Speed_limits_by_country) The national comparison seems like a rhetorical device, suggesting American's do something inferior to other countries, therefore we should change to keep up. Instead, you should only conclude that a decrease in speed could increase life expectancy.

> suggesting American's do something inferior to other countries

No, it very clearly is only suggesting that Americans are doing something inferior compared to the ideal.

Perhaps you're right regarding what the comparison is inviting. It might not be suggesting cross-country comparisons, but it's still making a normative statement concerning the ideal. My contention is that it should not do that; it should only focus on the decreased probability of death by reducing speed. Weighting the trade-offs is too objective.

(Edit: Also, it's a Canadian paper.)

A Canadian paper on US data, not enough people actually live in Canada for cars to approach each other on average. (I'm Canadian, but also making fun of the abuse of averages to describe this data).

Try this article: http://ajph.aphapublications.org/cgi/content/full/93/9/1384

Money quote: "While traffic fatalities from 1979 to 2000 declined by 50% in Canada, 46% in Britain, and 48% in Australia, the decline in the United States was only 18%."

What are the absolute rates? Here was a quote I enjoyed from your link that borders on tautology:

My more than 30 years of traffic safety research leaves little doubt that the 2 factors that overwhelmingly determine an individual’s risk in traffic are (1) the individual’s behavior and (2) the behavior of other road users.

Why does the author need over 30 years of research to come to this conclusion?

My anecdotal experience is that almost everyone is oblivious to the second factor. "Yeah I drive over the speed limit/tailgate/drive a motorcycle, but I'm a much better driver than the average idiot so it's not dangerous for me."

Interestingly, most accidents occur below the speed limit and increasing speed limits decrease accidents, because limits are artificially low and thus almost no one heeds them, except for a few people who do who cause accidents because accidents happen when the variability of speed is greatest.

http://sense.bc.ca/disc/disc-09.htm

What speeding does generally is increase the severity of accidents and alarmingly fast (Thanks, Newton!).

Energy levels follow square law and the human body has a rather low ceiling for the amount of energy it can absorb. It makes perfect sense that you're going to see large "averages" especially when the people going most excessively over the limit are the youngest and most inexperienced.

Now consider that young people also want to live in dense urban environments where there are a lot of other cars travelling at variable speeds, what you have is a recipe for high statistical impact accidents with energy levels following a square law with a low ceiling for death.

Lets look at a rather typical case: Young family, two kids, ages (28,28,2,3) they are travelling 10 over rushing to daycare and jobs, they run into an 85 year old grandpa driving 20 under. Everyone dies, so you have 10 over associated with (75-28+75-28+75-2+75-2) or 240 years of life expectancy, now on the other hand you have 20 under associated with -10 years of life expectancy. Lets not even get into who caused the accident according to anyone but a prosecutor.

Do this study on people over 75 and you'll find that old people should drastically increase the speed of their driving. Do this study on 0-10 year olds and you'll find that we shouldn't even be driving at all. The only thing this study says is that young people speed and when they die they have a disproportionate affect on average life span. The rest of it is just asinine statistical interpretations on data that have nothing to with speeding, and everything to do with the fact that the faster you are travelling the more likely you are to die when you crash. If they wanted to make this scientifically valid they should publish a chart showing at what age you should be speeding by how much, because once you're past 2/3rd life expectancy it's advantageous to speed according to this study, but this isn't about science, it's about speed = bad, so they can tax (err.. fine) you for doing it.

It's absolutely idiotic to add those numbers given the age and driving preferences and think that speeding is counter productive. This study is as stupid as a study that says that if Bill Gates moves onto your block that everyone on your block becomes a billionaire. Yes, it works on "average" but everyone knows that you still have to go to work (you may even have to speed to get there on time) in the morning if bill gates moves to your block.

I'd much rather get in an accident going 10 over a 50 zone than 5 under in a 100 zone (especially if it's on coming traffic).

Also, in Montana after a Judge invalidated their speeding laws as unconstitutional the number of accidents dropped.

http://www.hwysafety.com/hwy_montana.htm

I'll take real world data over a computer model any day of the week.

Except for the part about the kinetic energy, your overall argument is poorly supported and seems fatally flawed.

"...accidents happen when the variability of speed is greatest.

http://sense.bc.ca/disc/disc-09.htm "

There is nothing in the collection of short quotes, which you linked to, that supports this assertion. One of the quotes does mention speed variance, but as a possible factor, not as the proven greatest cause of accidents.

Also, your analysis seems to ignore all kinds of accidents except rear-end collisions, which account for a measly 5.4% of fatal crashes in the US (http://en.wikipedia.org/wiki/Epidemiology_of_motor_vehicle_c...). In head-on collisions, run-off-road collisions, collisions with animals, collisions at intersections etc. not only does speed variability play no part, but higher speed is certain to both increase the occurrence probability and aggravate the consequences.

Yes, I agree that raw speed would affect those conditions you mentioned, but it's primarily a misjudging the correct speed effect and not a "speeding" effect. (eg. the correct speed was probably under the limit), therefore driving 1-2KM/h slower the rest of the time would have absolutely no effect. This is why most accidents occur under the speed limit, because people are driving under the limit but too fast for the conditions.

What this study advocates is that we should drive a couple km/h slower ALL the time and what I'm saying is that we should drive faster than the limit almost ALL the time, however when conditions are bad we should drive SIGNIFICANTLY slower than the speed limit.

eg. Driving 5 km/h under the speed limit on the interstate on ice won't help you, but driving 5 km/h on ice on the interstate will. Unless you get hit by someone stupidly going 100 km/h on ice, my personal ice speed record is 140km/h in Idaho, but it took me 4 miles to slow down to 20 km/h.

We don't need to reduce our average speed, we need to reduce our speed greatly in very certain circumstances.

I agree with you that the speed should be much reduced in inclement weather. Other significant hazards can't be predicted as easily: drivers veering into the opposite lane; moose; debris on the road; people running red lights, etc. In all of these cases, driving a bit slower can result in significant reductions for both occurrence rate (extra reaction time) and severity (kinetic energy being proportional to v squared).

The statistic that most accidents occur under the speed limit doesn't say much. (I'm not aware of the study you refer to, but I suspect a good deal of the phenomenon is due to intersection collisions.) What you want is the converse - driving under the speed limit causes most accidents (I doubt it). And even that would not be sufficient: what counts is the number of fatalities, and there are probably fewer deaths in low-speed accidents.

I don't know about typical cases in US, but there typical speeding case with a youngster at the wheel is like this: drives like madman, goes off the road, smashes into a pillar or tree, kills himself, sometimes his passengers too. Age: 18-21. No grandmas involved.

The pro-speed limit argument falls apart as soon as someone says "but accidents are more deadly at 90mph" or "your reaction time is less adequate at 90mph." The problem is that while the statement is true, it's also true any lower limit, anything >0.

> The pro-speed limit argument falls apart as soon as someone says "but accidents are more deadly at 90mph" or "your reaction time is less adequate at 90mph." The problem is that while the statement is true, it's also true any lower limit, anything >0.

1. There is more than one argument for speed limits.

2. Just because it is true at any lower limit does not invalidate the statement. This just means that there needs be a balance between efficiency (higher speeds) and risk of collision (lower speeds). This is regulated, abet subjectively, through speed limits.

3. I doubt that it is true at 'any' lower limit. My guess would be that it is bounded. An accident when you are driving at 5mph is not much less deadly than an accident at 10mph. The chances that you are not the cause of the accident is much higher at lower limits.

one could also argue that the less time you spend thinking about cops, speeding tickets, and slamming on the breaks; the more time you can actually spend driving well.

Your comment is 10 times more intelligent and thought provoking than the article. Thank you.

It really would be interesting to see a more legitimate study on this topic.

Energy levels follow square law and the human body has a rather low ceiling for the amount of energy it can absorb.

Where does that reasoning come from?

IIRC, only fully elastic collisions (no heat dissipation) preserve kinetic energy. Linear momentum is always preserved though. As the name implies, it's not quadratic.

>The kinetic energy of a non-rotating object of mass m traveling at a speed v is mv^2/2, provided v is much less than the speed of light.

http://en.wikipedia.org/wiki/Kinetic_energy

> linear

I don't think that word means what you think it means

I'm sure simple things like not looking in mirrors to just being completely stupid and pulling asshat manoeuvres cause more accidents than speeding

In my time driving, I have never seen accidents caused by excessive speed but all the time by silliness which would have still resulted in an accident if people drove slower.

Methods of speed prevention such as cameras probably cause even more accidents due to last second braking.

What is needed is more education in safety on the road and how to control a vehicle or even in multi-tasking such as being told to navigate by yourself to a destination without being told where it as whilst the driver is still a learner.

When the speed limit was 55 and you happened to be driving in a rural state (ND perhaps), fatigue was a greater danger than anything else. The roads are long and straight and you don't have a huge traffic load. If you covered the driver's speedometer, the driver would naturally be going 75 - 85 on these roads (had several incidents with a couple of friends that demonstrated this). That extra 20 - 30 mph does save quite a lot of time.

I do wonder if the results and conclusions of this study are broken out by rural / urban roads. Or, like many studies I see, do they lump everything together or just not study rural areas.

I've actually been thinking about this a lot (recently started commuting from the East Bay to San Mateo). So it's awesome that others are too. Personally, I did a back of the envelope calculation for speeds. Was trying to estimate the time improvements of 65mph over 55mph v. the likelihood of accident. Suffice it to say, you all can do the math.

But that's not why I comment. I was actually thinking of a startup idea re: driving and accidents. Specifically, a site attached to Google Maps, etc., where people can register comments about where and how they got involved in an accident. If there were a way to feed in police report data, that would be awesome too.

But like the San Mateo bridge. I can see it from my desk. And I can see when it gets slow, and sometimes I'll check sigalert and note that there's been an accident (it seems to me usually at the top of the bridge where it's kind of windy and the furthest left lane has like no shoulder). Or otherwise I've gotten to know where accidents occur on my commute.

So my point is that all the information should be readily available so that people can figure out what are the high risk locations of their commute or trip. I think if you had a simple enough interface that integrated with Google Maps, people would voluntarily start using it. To my knowledge, there doesn't exist such a service. Perhaps I'm overly cautious, but I'd use it.

Would also be useful for people to register where they get their speeding and traffic tickets. As a long time Bay Area resident, I know what stretch of 280 the smokies like to hang out at a lot, and I bet that could be useful information to others, or even others with a satellite navigation program. Would be awesome if your GPS always had a threat level indicator based on accident and ticket likelihoods.

I believe there are radar detectors with a database of speed traps tied to a GPS receiver, but I'm not sure how they are updated. I agree that integration into a navigation system would be very useful, and technologically straightforward.

That would be awesome. You could even go the next step and include a HUD projected on a portion of your windshield...

Integrate it with your speedometer, look ahead on your GPS route, factor in time of day vs. likelihood of presence of law enforcement, take into account accident data and risk based on location and time of day, and rather than a HUD, simply have an ambient dash light that boils it all down and glows related to your risk. Integrate GPS+radar detector+Whispernet (real-time wardriving for speed traps).

I'm sure with the radar detector this would already break laws in about 30 states, but the core idea still would be viable if all you did was integrate crash data to alert people to risks in areas where their perception of risk was off.

If they remake the movie "The Gumball Rally" again in a few years, I'd expect to see this device featured by one of the teams.

And here I was worried that due to special relativity's time dilation, I was blurring by important moments outside my car. Thank goodness they were only talking about getting into crashes.

That was my first thought, too. I was hoping for a mathematical analysis in the difference in speed of aging between fast and slow drivers. The real paper was far more useful and mundane.

Med Decis Making has a Impact Factor of 2.597 while, top journals have Impact Factors >30

Although it is hard to compare impact values across disciplines, I would venture to guess this is not the best journal in the world.

http://www.sagepub.com/journalsProdDesc.nav?prodId=Journal20...

http://en.wikipedia.org/wiki/Impact_factor

I have a crazy idea ...

I'd like to see all drivers tested and graded for driving competency. Just because you can purchase a car and turn a key doesn't mean you aren't a vehicular homicide waiting to happen. Next, require all drivers to display their current driver "grade" on their car like a license plate.

Depending on your driver grade you are allowed to do different things in a vehicle:

Lowest Grade - can't drive on the highway (probably eliminating most fatal highway accidents) - can't drive vehicles over a certain weight (hopefully ruling out most minivans and SUVs) - can't drive high-performance vehicles (hopefully eliminating a lot of machismo stupidity) - can't drive above 65 mph - can't ride motorcycles on public roads (reducing harley and sportbike sales by about a million percent)

Middle Grade - can't enter the fast lane of a highway - can't drive above 75 mph

Highest Grade - can do pretty much whatever the fuck they want

etc

And of course everyone agreeing with you would be in the highest grade.

It seems that the authors of the paper are implicitly suggesting that speed limit should be lowered across the board.

How about we use that time and money and use it towards better driver education. Something more than a 20 questions test and 10 minutes in the car with a tester would be a good start. Maybe some sort of forced driving school?

Then, when everyone's better educated, we can raise the speed limits to reasonable levels and still have less accidents.

Many (hard to say how many) drivers will drive too fast because they are late for something. If you assume that their only goal is to either be on time, not be less late, then speeding makes sense, even in a simulation. Said driver has nothing to lose - they would be late if they didn't speed, crashes also make them late, but at least sometimes they won't crash and will indeed arrive on time.

This doesn't include the time you can lose by being pulled over and sitting around for at least 20 minutes? You could especially lose a lot of time eventually if you have to go to traffic court, or are arrested on an unrelated charge (i.e. drugs, half the reason police actually are interested in stopping people for speeding).

I wonder if drug users compose a higher proportion of speeders than general members of the population. It seems that random stops should be just as successful at finding illicit substances.

I've heard police say that they're suspicious of people driving exactly the speed limit, since it appears they may be trying to be extra careful about getting pulled over.

Just invest more in cars that drive themselves and we can forget all of this stuff. Our grandchildren (hopefully) are going to think we must have been terrified driving around in these big metal beasts surrounded by others doing the same.

Oh yes, by reducing speed, we could maybe reduce the number of accidents and thus reduce the travel time.

BUT - after few years, the drivers will adjust! they will still drive slower, but a little more risky. All the savings will vanish.

What about the extra time I get to live because I got to my destination faster? All evens out in the end, right?

Uh, no, the article is saying precisely that it doesn't all even out in the end: "A approximately 1-km/h (0.6-mph) increase in speed for the average driver yielded a approximately 26-second approximate increase (not decrease) in total expected lost time because the savings from reduced travel time were more than offset by the increased prospect of a crash."

arguments like this are put together for political reasons. someone is looking for more revenue.

ummm, you can't use observational data to draw conclusions like these. period. you can use them to hint at causations and effects of changes, but you absolutely cannot make conclusive statements like those made in this paper. REALLY bad science.

off topic: how this submission got into the 100 points feed?

Their conclusion seems incomplete, or maybe they came up with the conclusion before the study.

Other possible solutions include: increasing driving skill, paying more attention while driving (no sending text messages), etc

If -I- didn't crash, I lost no time. Someone else getting in a crash doesn't increase my travelling average.

It does if you are stuck in traffic waiting for the accident to be cleared.

Not how statistics work...

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