
Is Every Speed Limit Too Low? - ryan_j_naughton
https://priceonomics.com/is-every-speed-limit-too-low/
======
mcfunk
This is a fine analysis if you imagine that every road only ever has cars on
it. But this is not the reality, and speed of cars has a huge impact on the
fatality rates of vulnerable road users when they are hit.

Results show that the average risk of severe injury for a pedestrian struck by
a vehicle reaches 10% at an impact speed of 16 mph, 25% at 23 mph, 50% at 31
mph, 75% at 39 mph, and 90% at 46 mph. The average risk of death for a
pedestrian reaches 10% at an impact speed of 23 mph, 25% at 32 mph, 50% at 42
mph, 75% at 50 mph, and 90% at 58 mph. Risks vary significantly by age. For
example, the average risk of severe injury or death for a 70‐year‐old
pedestrian struck by a car travelling at 25 mph is similar to the risk for a
30‐year‐old pedestrian struck at 35 mph.
[https://www.aaafoundation.org/sites/default/files/2011Pedest...](https://www.aaafoundation.org/sites/default/files/2011PedestrianRiskVsSpeed.pdf)

Please think of everyone on the roads, not just drivers, when making arguments
like these.

~~~
civilian
I agree, let's fucking reduce pedestrian deaths! But you're ignoring the
analysis given in the article-- drivers already don't acknowledge speed
limits. From the article:

> _Luckily, there is some logic to the speed people choose other than the need
> for speed. The speed drivers choose is not based on laws or street signs,
> but the weather, number of intersections, presence of pedestrians and
> curves, and all the other information that factors into the principle, as
> Lt. Megge puts it, that “no one I know who gets into their car wants to
> crash.”_

Rather than speed limits, we need to look at other avenues to reduce
pedestrian traffic deaths. Just shooting from the hip, I think that we could
do more to communicate to drivers the presence of pedestrians, and to make
sure that rural highways and boulevards have shoulders or sidewalks for
pedestrians.

A more complete analysis of pedestrian deaths:
[http://www.popcenter.org/problems/pedestrian_injuries/](http://www.popcenter.org/problems/pedestrian_injuries/)

Here are some useful factoids:

\- _Finally, the more one drinks, the higher the risk of being involved in a
pedestrian-vehicle crash resulting in a fatality. One study found that out of
176 pedestrian fatalities, 86 of those involved pedestrians who had been
drinking, nearly all of whom had BACs of 0.10 percent or more._ \- _In
addition, the same study noted that 71 percent of all fatal pedestrian-vehicle
crashes in the United States in 2000 occurred in urban areas._ \- _Finally,
the majority of pedestrian injuries and fatalities happen to males between the
ages of 25 and 44._

This gives us a pretty targeted demographic! Start a "dangers of the road"
campaign targeted at pedestrians who are men, aged 25-44, drink at night and
who live in rural areas.

~~~
sushisource
Not only that, the article _specifically addresses_ parent comment's concerns:

> “I don’t want to lie to people,” Lt. Megge tells us. It may make parents
> feel better if the speed limit on their street is 25 mph instead of 35 mph,
> but that sign won’t make people drive any slower. Megge prefers speed limits
> that both allow people to drive at a safe speed legally, and that
> realistically reflect traffic speeds. People shouldn’t have a false sense of
> safety around roads, he says.

> If people and politicians do want to reduce road speeds to improve safety,
> or make cities more pedestrian friendly, Megge says “there are a lot of
> other things you can do from an engineering standpoint.” Cities can reduce
> the number of lanes, change the parking situation, create wider bike paths,
> and so on. It’s more expensive, but unlike changing the number on a sign,
> it’s effective.

Read the article before commenting, people.

~~~
sethherr
This is my _huge_ problem with the article - it argues we have no control over
speeding. And then it suggests places that ticket aggressively are behaving
irresponsibly, to the point of villafying a town in Missouri for enforcing its
speeding laws. All while skirting the fact that there is a clear correlation
between higher speeds and higher fatality rates.

Everyone knows a place cops like to hang out, and slows down accordingly.

Why not enforce speed limits more frequently so people obey them? Why suggest
a worse solution (encouraging all drivers to go faster) instead of punishing
more people for driving irresponsibly?

~~~
stellar678
The real way to make people drive a certain speed - is to design a road that
makes people drive that speed.

It's been a really slow process, but bit by bit we are beginning to recover
from the mistake of treating the design of transportation networks as a
technical engineering problem rather than a social design problem.

If you want people to drive 25mph, you have to design a 25mph road. You can't
treat it like an engineering problem and include a "50% safety buffer",
because then you designed a 37.5mph road and that's how fast people will
drive.

~~~
wvenable
What makes a road a 25mph road? One dangerous enough that people don't feel
comfortable driving faster -- how is that a solution?

~~~
mirimir
Yes, basically. You make traffic lanes narrower, with much wider shoulders
that are textured to discourage use. If there are bike lanes, you separate
them with rounded dividers. Trees in the center divider also help. As do
curves, and bumpouts around on-street parking.

~~~
jdavis703
People will just drive over textured bumps, I've seen it. You need to design
the road such that people will damage their vehicle if they drive dangerously
(things like on street parking, concrete bollards, tall curbs etc).

~~~
Animats
Bollards 3, bozos 0. [1]

The Sidney Harbor Tunnel had a serious problem with oversized trucks getting
wedged in the tunnel. Watch a truck drive past two sets of giant flashing
overhead warning signs. They stop only when they reach the final sign at the
tunnel mouth, a water curtain with a giant STOP sign projected on it.[2]

[1]
[https://www.youtube.com/watch?v=i_Cw0QJU8ro](https://www.youtube.com/watch?v=i_Cw0QJU8ro)
[2]
[https://www.youtube.com/watch?v=pRKA7m-tbqM](https://www.youtube.com/watch?v=pRKA7m-tbqM)

~~~
bbcbasic
An earlier bridge for them to crash into will also do the job quite nicely.

To be nice make it out of crumpling noisy material, not concrete.

~~~
masklinn
> An earlier bridge for them to crash into will also do the job quite nicely.

Except for the part where it requires significantly more maintenance to fix up
the bridge and it's incredibly dangerous for drivers following, whether the
truck hard-stops or gets its top sheared off.

~~~
matthewdgreen
Hanging bars seem to solve this problem. Makes a loud terrifying noise when
you hit them, but doesn't leave any permanent damage.

~~~
Animats
Truckers may not notice if the problem is at the rear trailer, as it was in
the video. The water curtain, although unusual, is not expensive. It's just a
sprinkler pipe and a very bright slide projector.

~~~
ascagnel_
Also, it's at the start of a blind curve -- the road design naturally leads
you to slow down as you approach, so stopping short be won't be as much of a
problem.

------
froh42
Over here in Germany a speed limit typically means there's a good reason to
follow it. On the Autobahn we've got places where there is no speed limit at
all (yep, there's places where I can legally go 250 km/h) and on other places
the speed may be set as low as 80 km/h (around 50mph).

A low speed limit typically is enforced with a traffic camera. Additionally
we've go a lot of dynamic speed signs which show a speed limit which fits the
current traffic conditions. (empty road at night - it's turned off. Rush hour
- 80 km/h. Fog - 60 km/h And several steps in between)

Not having a "fixed" all the time limit makes drives accept the speed limit
more easily.

Oh yes, and 85'th percentile. I frequently drive "+15km/h", so I go 95 when
there's 80 allowed because the fine when I get caught that is not too
expensive. (Fines for speeding are lower when you get caught outside city
limits, speeding in a residential zone or in front of a school for example is
one thing I have no tolerance for as well.)

~~~
strictfp
Germany is also the most stressful country to drive in I think. You usually
have three or four lanes - 80 kmph truck lane, 140 kmph standard lane, 200
kmph I'm slightly crazy lane and 250 kmph I'm a loonie lane.

When you accelerate from the 80kmph to the 140kmph you better have a good
engine or you feel stressed like hell slowing everybody else down.

And keeping right all the times just creates a lot of unnecessary dynamics in
traffic flow.

Don't even get me started on congestions when everybody slams their breaks and
hit the warning blinkers.

German traffic is for macho wannabe race drivers.

I rather have US traffic or the traffic in the Netherlands where everybody
just set their cruise control and drive casually.

In the Netherlands they also have trajectory speed checks, so you cannot speed
anywhere from point A to B, since they clock your total time. Works wonders
for getting a nice steady flow on the highway.

My 5 cents anyway.

~~~
arwhatever
I just returned from a 2 week driving trip through Germany and vastly
preferred driving there to driving in the U.S. The "always pass on the left
and never on the right" seemed like it led to more systematic and predictable
behaviors, and also tremendously reduced the competitiveness of the driving
experience as compared to the U.S.

It might all be cultural differences though. I noticed drivers seemed more
attentive and never used their phones (unless completely stopped in traffic
jams), whereas here in the U.S. it is extremely common to have drivers
piddling in the left lane and absolutely oblivious to the goings on around
them.

The only stressor I could see from driving on the autobahn was easily overcome
- before passing someone on the left, just be sure to check really, really far
back towards the horizon to make sure one one is coming.

~~~
saghm
> The "always pass on the left and never on the right" seemed like it led to
> more systematic and predictable behaviors, and also tremendously reduced the
> competitiveness of the driving experience as compared to the U.S.

Isn't that a thing in the U.S. as well? At least where I'm from (the
northeast), passing someone on the right generally gets you a loud honk on the
horn and occasionally a flip-off.

~~~
et-al
The problem with "pass on the left" is that it requires to drivers to
consciously treat the left lane as a passing-only lane. That doesn't happen in
California. The left lane in California is the "let me zone out and ignore all
these cars passing me" lane.

I disagree with strictfp that "staying to the right" creates unnecessary
traffic dynamics. What happens in California is worse. Someone holds up the
left lane, so all the faster cars will pile up on the right lane and try to
sneak in front of the slow car, but inevitably they'll cut someone off and set
off a chain reaction of braking for everyone that was patiently queued up in
the left lane.

(Granted on two-lane I-5 there are some legitimate a reason for this: the
right lane is used heavily by trucks, so the road wears down quicker and
becomes rougher in the right lane than the left. Naturally people gravitate
towards smoother asphalt. And if you just passed a truck a few minutes back
and are gonna pass another one again, why not just stay in this lane?)

~~~
zanny
This only happens on poorly designed roads that cannot handle their traffic
flow. Most people in most places will obey the left passing rule only so long
as there are enough lanes that the traffic fits in lanes - 1 so one can always
be open.

Since the US infrastructure system is a colossal piece of shit, highways built
40 years ago still stand exactly as they were then today having to accommodate
multiple times more traffic than they were ever meant to. This breaks down the
road rules when its bumper to bumper and every lane is backed up.

~~~
niftich
The scenario illustrated in the GP happens because the the rightmost lane is
subject to merging traffic from onramps and offramps, and also tends to be the
lane where trucks and vehicles obeying the speed limit (or both) congregate.

Meanwhile, the leftmost lane attracts people wanting to drive faster than
traffic, the people who just want to get one car ahead, as well as the people
who just want to drive without having to let cars in all the time.

If there's only two lanes -- like on most rural interstates -- and sufficient
volume exists to prevent the left lane from actually clearing out cars, this
creates a tragedy-of-commons situation in the left lane where there's more
empty space in the right lane than in the left. A subset of people will then
use the empty slots in the right lane to try to get ahead, making the
situation even riskier.

But this poster's right; the root cause is not enough lanes to ensure a high
level-of-service.

~~~
mrep
Totally agree, but the US is huge!

It would be much more informational to take into account things like average
number of cars traveling between various locations, number of lanes between
said locations, residential density...

~~~
et-al
Another issue is mobility in America. It's not uncommon for people to move
across the country for work. So cities like Portland or Austin don't expect
the sudden boom in population and increased traffic that entails.

------
mannykannot
One of the consequences of the authorities in the US tacitly accepting normal
traffic to flow at speeds considerably above the posted maxima is that they
could, if they choose to, pull over almost any of the drivers without there
being pesky issue with whether there was a valid reason to do so.

~~~
mighty_atomic_c
And, potentially, pull you over for complying with the speed limit if the
normal rate around you is large. Either way, you could lose.

~~~
danielpatrick
This is a tactic used by authoritarian governments and is a distinct reason
why laws that are poorly enforced are bad laws.

A poorly enforced law provides a tool for executives (the law enforcers) to
legislate (make their own laws) without any say from the real legislators.
It's a loophole of sorts in the US's separation of powers.

Take marijuana. It's illegal to smoke marijuana. It's not illegal to be black.
Yet the selective enforcement of the marijuana law allows authorities in any
given district to shape policy on race without ever having to explicitly put a
law on the books.

This is why the Computer Fraud and Abuse Act is so dangerous. It is broad
enough to be used as a tool to enforce laws that would be too unpopular to
explicitly pass.

It's also why threats from the US government to "ban encryption" should not be
taken idly. You think to yourself, "Certainly they couldn't ban encryption,
nothing would work without it." But they wouldn't enforce it across the board,
only selectively.

~~~
fpgaminer
EDIT: I was wrong. Original comment:

Last I checked, encryption _is_ banned in the U.S., isn't it? So it's already
the case that the government could selectively jail people for using
encryption, as it sees fit.

~~~
thethirdone
Source? AFAIK, encryption has never been illegal in the US. Export of
encryption was, but currently is in a reasonable state.

~~~
fpgaminer
Ah, sorry, forgot the "export" part, you're right.

According to
[https://en.wikipedia.org/wiki/Bernstein_v._United_States](https://en.wikipedia.org/wiki/Bernstein_v._United_States),
the regulations are still in effect. It doesn't say what the U.S. loosened
them to, but they do still exist.

------
ranger207
A big reason that the posted speed limit is only loosely correlated with the
actual speed driven is because the speed people go is not based on the sign,
but rather on the design of the road. There are various standards for traffic
engineering that define various parts of the road based on the speed expected
on them: things like lane widths, curve radii, the presence of fences and
guards, and more. A 35mph road will have a smaller turn radius than a 65mph
highway, for example. These standards have margins built in to them,
obstinately because the standards for faster roads are safer. If, for example,
you need a 200 foot turn radius to avoid skidding at 45mph, then the road will
be designed with a 300 foot turn radius that would prevent skidding at 55mph,
and a 55mph road will have a 400 foot turn radius that would prevent skidding
at 65mph. However, what happens is that people will drive at the speed that's
safe, not the speed that's posted. People will go 55mph around the 300 foot
radius turn that's posted for 45mph.

The solution to this seems to be to make the roads designed for lower speeds,
or to reduce the safety margin, or as other commenters suggest to add traffic
calming measures. I'm pretty sure this would reduce traffic speeds, but I
don't know if it would reduce traffic safety.

~~~
ThrustVectoring
Yup. There's a two-lane road in my hometown that was built and designed for 45
MPH traffic. The rich residents that had trouble pulling out of their
driveways onto that road successfully petitioned to get the speed limit
reduced to 35 MPH - but this does absolutely nothing to change the design of
the existing road. Traffic on that road routinely goes 45-50 MPH on it. If you
go the posted speed limit, it feels like you're crawling along.

~~~
thomastjeffery
Wouldn't it be nice if those "rich residents" focused on _fixing their
driveways_ instead of forcing everyone around them to alter their way of life?

~~~
ThrustVectoring
It's not a problem with their driveways. It's a geographic problem, really,
with lakefront houses in the 100-400ft strip between an arterial road and the
lake. The other side is a steep hill, so you can't make more room, and the
main road has to wind a bunch. You don't have the room to put in collection
streets and make controlled intersections, so you basically just have to make
them wait for a gap and pull out.

And as with pretty much any community that has that much value in their house,
they're huge NIMBYs.

------
phlillip
No. Cars today are _so_ much faster and more powerful than they were only 20
years ago. Here in the UK the speed limit on motorways is 70mph. I learned to
drive in 2000 in a Rover Montego that would cruise fairly well at that speed,
but later my family purchased the very popular VW Golf Mk4 TDi and all of a
sudden we could cruise at 100mph and barely notice it, the level of comfort
and noise insulation was that good. This is a car from 2002. But we are not
better drivers than people from 20 years ago; yet we all drive around in these
vastly overpowered machines. Brakes are better, tyres are better, sure, but
that can bring with it false confidence. Our reaction times are exactly the
same - if not worse thanks to all the modern distractions of technology - yet
there are vastly more vehicles on the road for us to deal with. I drive to the
speed limit everywhere I go, and I constantly have a queue of cars behind me.
If you're in a rush, get up 5 minutes earlier. Plan better. If you like to
drive fast, spend 30 minutes at a local go-kart track.

Cars are like bullets in our hands and should be handled with the utmost of
care.

~~~
manmal
OTOH, a limit of 70mph might be too high for my granny. And 100mph is a joke
for somebody with racing experience. Who do you design for? You are very
responsible and everybody should behave like you; but what if you get
diminishing safety returns when driving lower than 90mph because your reflexes
are good enough? Should you get fined for driving 90 then, and my granny (who
can barely handle city traffic) is not fined for driving 70 while endangering
other people?

Edit: Forgot to add my favorite solution: Add a very high, hard speed limit
(130mph?) on all streets, and let traffic signs serve as recommendations.
Obviously, also limit to walking speed in neighborhoods where kids play in the
streets, or city centers.

~~~
jl6
I hear a lot of people claim they are such good drivers they should be allowed
to drive faster.

I don't trust their self-evaluation of their own skills.

------
enoch_r
On highways, the 85th-percentile rule makes some sense. The evidence seems to
suggest that raising speed limits slightly increases fatality rates, but not
accident rates, and doesn't have _much_ influence on driver speed.

At the other extreme, on neighborhood streets in residential areas, the
rationale for the 85th percentile rule (reducing the speed differential
between cars traveling in the same direction) is absurd: these speed
differentials are _much lower_ and _much less important_ than other speed
differentials. If a car driving down my street at 30mph has trouble dealing
with a car going the same direction at 20mph, it will also have trouble with
the kids playing basketball in the street, or the car headed the opposite
direction without room to pass, or the car backing out of a driveway, or the
bike going 15mph. Conflicts between drivers headed the same direction are a
non-issue on these types of streets.

And there are streets in the middle. A major commercial street in my town is
four very narrow lanes (the right lane is actually less wide than a city bus,
so when a bus is traveling the same direction you must enter the oncoming lane
if you try to pass), with very small blocks, crosswalks at every intersection,
tons of pedestrians and cyclists, tons of cars turning left across traffic,
etc. Should this be set at the 85th percentile speed? Although it's more
debatable, again, I don't think that the speed differential between cars
traveling the same direction is likely to be a major contributor to fatal
accidents here--on a busy urban street like this the danger is much more
likely to arise from the speed differential between pedestrians and cars, a
car turning left and an oncoming car, cyclists and cars, etc.

~~~
notahacker
Not to mention that one of the main reasons for speed limits typically being
30mph or lower in urban areas even where the roads are fairly easy to drive on
is those kids playing basketball in the street or cyclist are _much_ more
likely to survive an impact even if the driver isn't able to anticipate and
avoid it than at 40mph, when they have a 95% chance of being killed (it's 95%
chance of _survival_ at 20mph)

Obviously this applies less to country roads where pedestrians are rarely
encountered, speed limits are well over 40mph and drivers often should be
paying more attention to the bends ahead of them than the notional speed limit
when judging how fast to go anyway.

~~~
panic
As the article says, people won't slow down just because you posted a lower
limit. A better way to protect these children would be to change the design of
the road (this report seems to be a good overview of ways to do this:
[https://www.monash.edu/__data/assets/pdf_file/0007/216727/mu...](https://www.monash.edu/__data/assets/pdf_file/0007/216727/muarc298.pdf)).

~~~
hvidgaard
In the last 20 years Denmark have had focus on doing this in villages along
main roads. Before it was normal to see cars on through the village with
100kmh, now they'll crash if they try to do that, because on entry and exit in
the village there is a chicane.

------
clairity
beyond agreeing with just about everything in the article, a few points to
add/emphasize:

* speed limits are set at the 85th percentile of speeds to minimize speed variance, giving slow drivers a target speed and thereby making them go _faster_ than they might otherwise go (but still at a safe speed).

* larger variances in speeds correlate with both greater traffic and frustration. if highway patrol could enforce just one law, it should be that drivers should move to the right if they are not passing cars on the right. this allows faster cars to clear out of congestion, increasing the overall average speed and throughput for a given section of road. it also reduces overall frustration.

* traffic enforcement as a revenue generator creates a perverse incentive and adversarial relationship largely exacerbated by artificially low speed limits. let's abolish those limits and bad incentives and give the police more time to develop relationships within their community.

* change the term "speed limit" to "safe speed" on signs (along with commensurate fines/laws), because that would have the same normalizing effect on speed variance, while also removing the revenue incentives for police.

* distracted driving is the real killer on the roads, not speed. changing roads to make them more hazardous (like narrower lanes, obstructing sightlines) probably reduces distracted driving more than it reduces speeding (just my conjecture), and thereby lowering accidents. i don't mind narrower lanes and such, but i'd advocate separating cars from bikes and pedestrians as much as possible so that cars can still move at a good clip while providing greater safety for pedestrian and bike traffic.

~~~
Danihan
>while also removing the revenue incentives for police.

Well that will never happen..

------
bryanlarsen
Virtually eliminating road fatalities is quite possible, Sweden has done it.
The low speed limits and infrastructure spending on separated pedestrian &
cyclist paths would never fly in the United States.

[http://www.visionzeroinitiative.com/](http://www.visionzeroinitiative.com/)

~~~
AndrewKemendo
I feel like there should be an internet wide ban on comparing Sweden and
Norway to the US, China, India or Russia or, hell pretty much anywhere.

Obligatory Reference to wit:
[http://www.slate.com/blogs/the_world_/2014/08/29/will_everyo...](http://www.slate.com/blogs/the_world_/2014/08/29/will_everyone_shut_up_already_about_how_the_nordic_countries_top_every_global.html)

~~~
foxbarrington
I was hoping there would be a novel reason to stop comparing Nordic countries
to the rest of the world. Sadly the main points the article makes are: (1)
they are welfare states and that would never be welcome anywhere else and (2)
they have small populations.

So... (1) maybe a welfare state isn't that bad? and (2) that's akin to not
believing in small-scale trials/pilots because they're small.

~~~
AndrewKemendo
I think #2 is the most valid and compelling reason for a host of reasons. The
other thing that is in the article that shouldn't be dismissed the homogeneity
of the population. That goes a long way toward making #1 possible as it's
easier to empathize across a smaller population.

~~~
corybrown
Plenty of US states have small populations, no? Also lots of states are
comparatively homogeneous (Sweden has 19% of population as recent immigrants).

~~~
AndrewKemendo
Sure, so those comparisons are actually more apt! You rarely if ever see them
made however.

Georgia, Michigan, NC and NJ are the closest in size but that's about where it
ends. Michigan probably has the closest demographic homogeneity. However the
existence of the federal government as well as natural resources as a economic
base throws a wrench into any further comparisons.

~~~
corybrown
> natural resources as a economic base

True for Norway, but not any other country in the neighborhood (fine, Scotland
I guess)

------
ja27
The road to my son's high school has a 5 MPH speed limit. Have you ever tried
to drive 5 MPH? My speedometer doesn't register that low. My car goes faster
than that at idle.

~~~
Neliquat
My favorite are the 7.5mph, 14mph, and other odd increments ment to convey
percision, while we just ballpark most slow speed limits. Reminds me of the
guy who set all his meetings at exactly 7 minutes after the hour to convey
promptness.

~~~
brewdad
I read somewhere that the original goal of those oddball speed limits was to
get drivers to notice them and therefore, hopefully, obey them. It's easy to
tune out yet another 25 mph sign, but 23 mph stands out.

~~~
Dylan16807
But why? I understand 25mph just fine. 23mph is only going to distract me.

~~~
Markoff
i think that's the point, so you pay close attention to speed limits instead
of overlooking them if they are everywhere same, of course you can drive at
common lowest denominator and don't be distracted

~~~
Dylan16807
Paying inordinate attention to the limit means not paying as much attention to
driving.

I have never paid too little attention to the speed limit being 25mph. I have
always been very well aware of being in such a residential zone.

------
AStellersSeaCow
FTA: "Fortunately, American roadways are safer than ever, with highway
fatalities at historic lows. Roads can be dangerous, but the perception of
roads getting increasingly dangerous is a false one." ... "Published Jul 23,
2014"

And then: [https://www.nhtsa.gov/press-releases/traffic-fatalities-
shar...](https://www.nhtsa.gov/press-releases/traffic-fatalities-sharply-2015)

~~~
dom0
> American roadways are safer than ever

Well, even then, the US still has somewhere around 3-4 times more deaths on
the roads per capita than other western countries.

~~~
kej
Per capita, or per miles driven? My limited experience is that people in the
U.S. drive a lot more in general, so per mile driven would be a more
meaningful measure of road safety.

~~~
dom0
IIRC it's still like 30-40 % higher when considering distance.

------
davidgay
I have a hard time taking the conclusions seriously when I compare the
situation with Switzerland.

The current Swiss yearly deaths are around 250, a very significant drop from
the typical 1000 I remember growing up in the 80s - [http://www.oecd-
ilibrary.org/docserver/download/7515011ec041...](http://www.oecd-
ilibrary.org/docserver/download/7515011ec041.pdf?expires=1493191296&id=id&accname=guest&checksum=918FF5DCE3816234431A7F71F8965204)
lists a maximum of 1720 in 1971. As the population increased about 25% in the
same period, that's about an 8x drop in per-capita rate.

In the same period, US fatalities dropped from 52000 to 35000
([https://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_i...](https://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_in_U.S._by_year)),
for a per-capita drop of 2.3x (the per-mile drop is 4x, the current Swiss per-
mile rate is 60% of the US one).

In the period I remember:

\- speed limits were reduced in town from 60 to 50km/h, on highways from 100
to 80 km/h and on freeways from 130 to 120 km/h

\- speed limit enforcement became much more pervasive (there's an automated
radar every 10km or so on busy freeways?)

\- cars got safer (this applies everywhere)

\- drunk driving limits were reduced (and people's attitude to driving after
drinking changed substantially)

So suggestions that speed limits are irrelevant and pointing to reduced death
rates in the US as evidence are not very convincing when other countries saw
substantially larger improvements over the same period.

~~~
GuB-42
Is it also possible that the roads themselves became safer? Better signs,
redesign of dangerous intersections, highway bridges and tunnels replacing
mountain passes, barriers, lighting at night, good maintenance, etc...

~~~
scott_karana
It's also possible that drivers has simply been shamed into driving _less_ ,
not more safely.

I'm curious what per-capita driving hours and mileage changes look like over
the same period.

------
iagooar
What is ridiculous is that in many European countries speed limits haven't
changed since the 70's, when cars used to be a lot less safe and driving
education was a joke as compared with today's standards.

You can see that this holds true when looking at some of the Eastern European
countries that only recently got better road infrastructure. E.g in Poland,
the max speed limit at a highway is 140 km/h, whereas countries like France or
Spain keep lower limits (130 & 120 respectively).

I think that today, any highway limit below 140 km/h is just obsolete and
should be revised. Now, I would prosecute harder those who speed in urban
areas, where the risk of hitting pedestrians or cyclist is real.

~~~
tqkxzugoaupvwqr
1\. The speed limit should be tied to average driver reaction times, not the
engine or safety of the car.

2\. Speed limits help maintain a steady flow of traffic.

My father found driving in France terrific because all lanes were limited to
130 km/h. Steady flow, no stress. In Germany, driving on the autobahn is
stressful. The speed difference between the lanes is too big. From my
experience, it is: right lane 100 km/h, middle lane 140 km /h, left lane “Get
out of my way you sucker!!” >180 km/h. Passing someone on the middle lane
means taking the left lane and accelerating as fast as possible because the
next space ship SUV is coming closer at rocket speed. They tailgate you,
sometimes flash lights or use their left blinker to bully you to switch lanes.
Because of that, many people cut into the safety distance of the car they just
barely passed to get rid of the bully.

The speed difference also causes backpropagating traffic jams. To the observer
there is no obvious reason where the slowdown comes from. It was simply
created by people driving too fast compared to the car in front of them,
having to brake, causing the cars behind them to brake, etc.

~~~
lloeki
> 1\. The speed limit should be tied to average driver reaction times, not the
> engine or safety of the car.

Hence why distance to the car in front matters, proportionally to speed, _not_
speed itself as an absolute metric. 180kph is not a definitive tailgating
trigger when people behave. Case in point, in France people regularly tailgate
you too even at 130kph, even more so because they feel safer due to the
comparatively reduced speed.

> The speed difference also causes backpropagating traffic jams. [...] It was
> simply created by people driving too fast compared to the car in front of
> them, having to brake

It was created by people either braking too late and having too much of a
tendency to tailgate you, or jumping out of their lane and sitting there, and
it happens just as much in France. It's a property of reaction time and
distance WRT speed, not speed itself.

> They tailgate you, sometimes flash lights or use their left blinker

I've mostly seen this behaviour when the car either cruises at a reduced speed
on the left lane or irresponsibly takes over when it should have no business
in doing so WRT current traffic: it's just as disrespectful to others to
tailgate someone as it is to take over and block a lane when you're driving at
a locked 140kph to overtake someone at 138kph and there's constant faster
traffic on the left. I've also witnessed people playing vigilante and do this
voluntarily precisely because of the existing speed limit.

My experience is that most issues on the road are a byproduct of terrible
individualistic human behaviour, and setting limits on arbitrary metrics do
not solve that.

------
athenot
If reducing speed is really desired, there are other ways:

\- make roads narrower (either by optical illusion with narrower painted lanes
or physically)

\- reduce stretches of straight road: traffic circles are great at breaking up
a straight line

\- remove all straight lines from highways, making them perpetually in a
slight curve. This is something that has been done in many place in Europe for
newer highways. This breaks up the monotony of being on a straight stretch of
highway and therefore feeling the need to drive faster. As an example, notice
the slight curves in the limited access highway (A5) and compare to the 2-lane
road that runs parallel to it (D605) in segments of straight lines:

[https://www.google.com/maps/place/A5,+France/@48.4802471,2.7...](https://www.google.com/maps/place/A5,+France/@48.4802471,2.7953364,12z/data=!4m5!3m4!1s0x47ee948c507acd09:0x3c978e6c3b47deb9!8m2!3d48.2729269!4d3.8765452)

~~~
wffurr
The bottom line of the article gets it totally backwards: "Raise speed limits,
make roads safer." It should really be "design roads for lower speeds, make
roads safer".

~~~
loeg
They aren't mutually exclusive. Existing roads are wide and straight and have
too-low speed limits. Revamping them to be lower speed roads takes more money
than just fixing the sign.

------
jwagenet
The officer in the article is absolutely right: if communities want to reduce
speeds then they need to do more the number on the sign. I notice the wider
and more open the roadway is, the faster I'll drive. Even if a large bike lane
replaces my lane, that space is still available to take up the slack for
mistakes. Whereas a narrow county road or narrow residential street lined with
cars will certainly slow me down, especially with oncoming traffic.

~~~
rplst8
Agree. One thing I've never understood is why people ever thought it was a
good idea to combine vehicle, foot, and bicycle traffic on essentially the
same roads. Side walks are just another lane.

Communities need to enforce zoning that makes certain areas (malls, downtown,
etc.) pedestrian areas only. Additionally, separate bicycle traffic onto
different paths.

That would probably increase safety quite a bit.

~~~
Zak
How many people are injured or killed annually by motor vehicles traveling on
sidewalks?

~~~
tbihl
I think you meant to put this into a Google search, not a comment.

------
noonespecial
Should it not be very much dependant on the car? A modern car with new tires
can safely go (and stop) much better than a junker from the 70s with no abs,
bald tires and no independent suspension.

~~~
Neliquat
Yup. My car can pull 1.17g on a skidpad, but you pulled me over instead of the
SUV that can barely stay in his lane at legal speeds. A classification system
seems logical. We already have one, trucks often have seperate limits. Why not
one for people with better car, and perhaps a driving skills certification.

~~~
chadgeidel
This makes sense (and I have often advocated for it as well) but I would
imagine enforcement would be ridiculous.

I'd like to see more license classes than "Car, Car with Motorcycle rider, CDL
(over 13 tons), and CDL with Trailer". One could start with a "light weight
class" like moped/motorcycle/small car, then have a progressive system for
"heavy weight cars" (SUV or pickup truck) or "high HP/Ton cars" (Sports car).
These "advanced licenses" would have a higher standard of testing and stiffer
penalties if you are driving a car that meets these higher-spec classes.

~~~
VonGallifrey
We have something like this in Europe. There is a classification between
different vehicle types. There is A,A1 for Motorcycles of different sized
motors; B,BE for cars below 3.5 tones; C,CE,C1,C1E for "cars" above 3.5 tones
and D,DE,D1,D1E for buses. There are also classes like M which are for
Motorcycles caped at 25km/h which can be obtained even at 16. All the other
ones only for 18 and older.

------
tromp
In my experience, the 85th percentile is at the speedlimit + 10-15 mph. It's
as if people have decided they're unlikely to be ticketed by going "only" 10
mph over the limit. I rarely see anyone driving at or below the speed limit.

In Europe I've gotten tickets driving only 5mph over the limit (58 km/h on a
50 road), which would explain why the 85th percentile is closer to the actual
speedlimit there.

~~~
bspn
My wife was born and raised in the Southern US, and whenever we travel on the
interstate system here she assures me that so long as I remain within 15mph of
the posted speed limit I'll never be ticketed. When she first told me her
theory it's fair to say I was a deep sceptic (as a foreign-born LPR), but
nearly a decade on and she hasn't been wrong yet.

I will admit though, she counsels me against following the rule in Virginia
because the cops there don't mess around.

EDIT: I should add that 15mph over the limit is usually "going with the flow".
If the other cars are traveling at 70 then 85 really stands out.

~~~
mikeash
Yeah, absolutely do not follow that rule in Virginia. We have roads where the
speed limit is 70MPH. If you're driving 80MPH or over, it's automatically a
reckless driving charge, which is an actual crime, not just a moving
violation. And if your attention drifts a bit and you accidentally break
90MPH, you'll probably end up in jail.

My usual rule is 5MPH over. I sometimes increase it to 10MPH, but it works
almost everywhere.

~~~
Neliquat
In general:

5 over is safe everywhere in the USA except school zones. 10 is generally safe
in suburban and rural areas. 14 over on highways, unless mitigating situations
exist (bridge, visibility, twisties)

Beware, almost every area has some county or township that abuses their little
patch of highway, and they tend to be well known to locals, but prey on
passers by.

This is not bulletproof, but has been my experince.

~~~
brewdad
This is true but personally I would rather see this shift to something closer
to +10%. Going 35 in a 25 mph residential zone puts anyone not in a car in
significant danger. Going 27 or 28 doesn't change the risk nearly as much.

This rule of thumb still allows for 61 mph on urban freeways and 77 to 83 on
rural interstates.

------
jaclaz
There is another factor (human) that is not taken into consideration about
accidents.

Just like the recent discussion about "troublemakers", 90% to 95% of drivers
are - with different levels of driving competence - OK.

It is the remainining 5%, maybe 10%, that create most of the issues, directly
or indirectly, that is not only speeding, it is often distraction,
aggressivity at the wheel, etc..

One of the reasons why "black boxes" that record driving habits are not as
common as they could or should be, besides of course the usual privacy risks,
is that everyone is afraid if the data that would come out of them.

If all drivers were monitored it would likely come out that a small minority
(the said 5% or so) should simply be deprived of the right to drive any
vehicle (no insurance would ever cover them, as insurance is about risks, not
about certainties) and this would break quite a few "social contracts",
including the unwritten one in which there is a "right to drive" (because our
cities and lives are organized in such a way that a car is needed to commute,
to take kids to school, etc.).

------
tempestn
> If people and politicians do want to reduce road speeds to improve safety,
> or make cities more pedestrian friendly, Megge says “there are a lot of
> other things you can do from an engineering standpoint.” Cities can reduce
> the number of lanes, change the parking situation, create wider bike paths,
> and so on. It’s more expensive, but unlike changing the number on a sign,
> it’s effective.

This paragraph is really key. You want to design the road and the area around
it to encourage an appropriate speed, and then set the speed limit at that
speed (which should work out to the 85th percentile of what people would drive
anyway). IMO most freeways, at least where I'm from, should have higher speed
limits (and are already designed to support them). Some residential streets
should probably have lower ones, but would need design changes to encourage
people to actually drive at an appropriate speed.

------
givemefive
There's a 3 lane (each way) street with traffic lights in my suburban city
that I drive every day. I refuse to go above the speed limit (40mph) while
driving in general but the generally accepted speed is 55mph and there's no
enforcement.

Either they need to raise the limit or enforce it. I'm sick of being the
asshole going too slow.

Also my speed is generally more a function of gas mileage than anything else.
With stop lights littering the route I don't feel that driving 55 is any
faster than 40. It just wastes more gas. So maybe it wouldn't even make sense
to raise it and instead it just needs to be enforced.

~~~
SilasX
You're not bothering anyone if you stay to the right (assuming US) so they can
pass.

~~~
rplst8
I think this needs to be drilled into young drivers heads so the highways of
the future have less morons on them.

In fact, I think it needs to go a step further - ALWAYS stay to the right.
Only move to the other lane to pass or turn left.

~~~
Sargos
Staying out of the passing lane when not passing someone is actually the law
in many states. You must keep right if able.

~~~
ubernostrum
All 50 US states have _some_ type of keep-right law. Whether it's an absolute
"keep right unless actively passing" or a looser "keep right when slower than
other traffic" varies, but all of them have some kind of enforceable keep-
right rule.

~~~
username3
All US traffic laws come from the Uniform Vehicle Code. Keep right rules are
meant for absolutely slow traffic and not for driving the speed limit. The UVC
has keep right exceptions for divided highways with multiple lanes going in
one direction.

Passing left laws were intended for two way streets with one lane in each
direction when the only way to pass is by driving on the lane going the
opposite direction.

~~~
u801e
> Keep right rules are meant for absolutely slow traffic and not for driving
> the speed limit.

Do you have a citation for that? Many state laws use the speed of traffic as a
reference to define slower as opposed to using the posted speed limit as the
reference. If they meant to say only slower than the speed limit, then the
text of the law would be explicit on that point.

------
callesgg
One problem i see here is that what we call the "speed limit" is not simply a
speed limit it is the speed you are suppose to drive at.

~~~
Qantourisc
Yes, this is a problem. I would often drive slower, if there wasn't a speed
limit. Personally I think a recommend and speed limit should exist, (on the
same road/sign).

~~~
iagooar
That's the German approach actually. There is no speed limit on some of the
highways, yet the recommended speed is 130 km/h.

------
iambateman
Genuine question...if we really cared about speeding, couldn't we just put
speed cameras everywhere and issue tickets automatically for people who are
driving too fast?

The randomness of having a human officer grab me (not the other 1,000 people)
off the road for going too fast feels unfair and ineffective.

~~~
jpmattia
> _couldn 't we just put speed cameras everywhere and issue tickets
> automatically for people who are driving too fast?_

There are stretches in DC with exactly that strategy. As a consequence, people
speed and then hit the brakes right before the cameras.

I'd love to know the accident stats right around those stretches.

~~~
gsnedders
Average speed cameras are a solution to that problem and frequently used for
long-running road works on UK motorways.

~~~
Markoff
how do they deal with stopovers? average speed measuring is useful only for
continuous trip and very short distances between measuring points so they
can't be cheated by stops, but I can see how delivery driver with many stops
could easily break speed limits even with average measuring

~~~
gsnedders
They're only done on motorways (~freeway) in general, and there tend to be at
the very least cameras before/after each junction. Any directly on-carriageway
parking places tend to be closed off, hard shoulders are for emergency use
only, and service areas are considered junctions for this.

I don't think I've ever seen anywhere with them with less than, say, half a
mile separation between junctions. At that point, you just get normal speed
cameras.

------
kylehotchkiss
My favorite is when people go 40mph on a 65mph road and nearly cause everybody
else who was previously driving safely and happily to nearly rear end each
other and cause unnecessary brake and tire wear. There ought to be some
sterner punishments for driving too slow as well.

------
mikeash
As usual, the answer to the headline is "no." Probably most freeway speed
limits are too low, and many others, but lots of smaller streets have
appropriate limits, or even ones which are too high.

It's a fun (and annoying) game to observe how people's speed varies compared
to the limit. I almost always go at the limit plus 5MPH unless that would make
me dangerously slow. Sometimes this makes me the fastest car on the road, and
other times the slowest.

There's a road I drive about twice a day where the first half has a 25MPH
limit and the second half is 35MPH. I'm usually a slowpoke on the first half,
building up a queue of cars behind me, and then end up the fastest car around
on the second half. (And to preempt any haters, the 25MPH segment is less than
a mile long, so I'm not severely inconveniencing people.)

Rural interstates here have a 70MPH limit, so I go 75MPH. Most people go
65-70MPH. As you get into the city where I live, the limit drops progressively
to 55MPH, and most people go... 65-70MPH.

~~~
mjevans
My opinion is that most are not too high. Though there are many that may
/technically/ be that way due to the driveways of older houses which are a
legacy from before the rest of the city moved out to the area. Society should
do a better job of encouraging the increase of density and arterial
conversion.

------
fenwick67
"I’ve found that about 10% of drivers truly identify the speed limit sign and
drive at or near that limit"

I really hope this is not the case

~~~
awinter-py
Former FDA chief john nestor was known in DC for setting his cruise control to
55 and parking in the left lane.
[https://en.wikipedia.org/wiki/John_Nestor](https://en.wikipedia.org/wiki/John_Nestor)

Some cops claim that aggressive traffic enforcement leads to knock-on effects
in reducing gun crime:

[https://www.nhtsa.gov/staticfiles/nti/pdf/809689.pdf](https://www.nhtsa.gov/staticfiles/nti/pdf/809689.pdf)

> Gun seizures by police in the target area increased by more than 65 percent,
> while gun crimes declined in the target area by 49 percent

It probably makes sense -- any kind of warrantless search has the potential to
decrease crime.

~~~
wyager
I'm not surprised that someone with a psychopathic desire to inconvenience
people would seek employment in government bureaucracy.

~~~
username3
That "psychopath" was the major force in bringing to light the effects of
Thalidomide in the early 1960s. He stood up to drug companies.

> A plot was hatched, fueled by indignation: "By God, I've paid taxes for a
> long time -- and more than a lot of those trucks." First he consulted with
> the commonwealth attorney's office and other traffic authorities to ensure
> that his plan was legal, that passing on the right was acceptable on
> multilane highways and that traveling over 55, even to pass, was against the
> law.

[https://www.washingtonpost.com/archive/lifestyle/1984/11/21/...](https://www.washingtonpost.com/archive/lifestyle/1984/11/21/john-
nestor-strife-in-the-fast-lane/177dbb31-aeed-499e-8be4-9de519efd37a/)

------
panglott
Maybe police should try enforcing the traffic laws?

I refuse to speed; I think it is immoral. This is because I ride a bicycle
everywhere, and the extent to which people speed on surface streets has an
obvious and tangible effect on my safety. My town has a narrow bridge that
used to be the only way for cyclists to get across the river, where drivers
routinely exceed the 35 mph speed limit by 20 mph or more. It is terrifying,
and people have gotten killed. I wish they would put a speed camera on that
bridge.

The argument that "the speed limit doesn't matter because people will travel
the same speed" only makes sense under the assumption that the only people who
will use the public roads are drivers who feel like they can do whatever they
want. Plenty of drivers feel entitled to run red lights, too, and that causes
more collisions.

~~~
lacker
The point of this article is that often, speeding is _safer_ than obeying the
speed limit. In those cases it seems moral to speed.

~~~
trgn
For drivers, I'm sure. Not for cyclists or pedestrians. Depends on the street
of course.

In general, I think speed limits can be higher on highways, but should be much
lower and actually enforced in town. Fast cars are absolutely terrible for the
safety and comfort of walkers and bikers.

~~~
mannykannot
I _think_ the article was about highways specifically (the arguments do not
really hold up in an urban environment), but I don't think it said so
specifically.

~~~
panglott
Probably, but the title of the article is "Is Every Speed Limit Too Low?"

People seem have a bias towards thinking about speed limits in terms of
interstate travel speeds, which frequently have been raised to 70–80 mph
anyway.

Perhaps this is because most speeding enforcement is on interstates and there
is relatively little enforcement of speed limits on surface streets unless
they are very egregious.

------
jakehilborn
Slightly off topic. If you're interested to see how time saved speeding
actually nets you check out this app I wrote:
[https://jakehilborn.github.io/speedr/](https://jakehilborn.github.io/speedr/)

~~~
Neliquat
I used to time my commute to the second and found that 'timing the lights'
still got me there faster than the day I drove 20 over like an asshole.
Changed my whole driving outlook.

------
turc1656
Reading through a number of the comments, my thoughts on this matter may draw
some ire, but here they are anyway, FWIW.

I would really like to see some consistency applied to how the law is enforced
and written when it comes to traffic safety. What I mean by that is driving is
clearly an inherently dangerous activity given the frequency of traffic
incidents on a per-capita basis compared with just about anything else. Well,
for every other type of inherently dangerous activity we are all forced to
sign wavers basically saying that we understand and accept said risk and we
are willing to take that risk. That acceptance protects mostly everything but
situations involving negligence or gross negligence. I never understood why
driving is treated any differently.

Also, when you look at what traffic law is at its most basic level, it makes
little sense when compared to the rest of the body of law that exists for
everything else. Traffic law exists primarily to increase safety on the roads
and reduce the risk of accidents. Now, statistics do show that enforcing
traffic laws do actually make the roads safer. I acknowledge that up front.
But my issue with them is that the overwhelming majority of traffic citations
are issued for violations that have caused no harm. That is, drivers are cited
and forced to pay a fine simply for increasing the odds of an accident
happening. The accident need not actually have occurred. Nowhere else does
that shit fly. You can't go to court and sue someone for anything without
there being some sort of harm/tort/injury/etc. That's basic law. If someone,
for example, tried to defraud you but you were slick enough to spot it and
stopped it, you can't sue them in court because you didn't actually lose
money.

I'd much rather see a situation where either people accept the risks of the
road and only have limited options like negligence and perhaps a few others -
or, to see cops citing people only when they are deemed the cause of the
accident or the rare cases when someone is driving so insanely on the road
that their driving alone is enough to justify gross negligence (i.e. racing or
doing 50 in a 25 in the rain).

~~~
turc1656
A follow up thought - the article also mentions that revenues generated from
citations are another possible reason for the speed limits being what they are
and speed traps being a known money grab nationwide. This is definitely true,
and pretty much everyone who drives knows this intuitively. The authorities
always like to claim that it is always about safety.

Well, I might believe that if they didn't derive a sizable chunk of revenue
from this enforcement. I think society as a whole might actually believe them
if and only if it became a legal requirement that any and all revenues coming
directly from fines are required to be donated to charity. Then I would be
far, far more likely to actually believe that I'm getting a citation because
the officer truly thinks I did something unsafe and worthy of being fined for.
Since courts typically also assign a court fee if you decide to (or are
required to) show up in court, there would need to be some kind of protection
to prevent them from jacking up the court costs as well.

~~~
u801e
I suggested eliminating fines and court costs associated with a traffic
citation and just rely on license demerit points as the penalty for a traffic
violation. Once a diver accumulates enough demerit points on their license,
it's suspended. If they're caught driving on a suspended license, then they're
arrested and taken to jail pending a hearing.

I strongly suspect that without the possibility of making money from traffic
violations, most law enforcement agencies wouldn't bother doing any
enforcement.

------
web007
> If someone could wave a wand and get every American to drive below 60 mph,
> roads would be safer.

That wand exists - it's called "enforce the law". Increase penalties, or
decrease them if you need a revenue-neutral plan, but enforce that 60MPH is a
limit, not a suggestion.

This article parrots the same concept as most speeding solutions: speed
doesn't kill, only variance in speed is dangerous. That makes perfect sense.
So why increase the possible variance from zero, and why let people complain
about driving at the limit being too slow? If you're above the limit, _you_
are increasing the variance, and _you_ need to slow down.

~~~
Sargos
Your logic while flawed is actually sound if you increase the speed limits to
realistic levels and then enforce them at that point.

Enforcing the limits when they are artificially low helps no one except for
the police.

~~~
dragonwriter
> Enforcing the limits when they are artificially low helps no one except for
> the police.

Sufficient enforcement will, over time, reduce speed variance, which is the
behavioral problem which leads to the conclusion that speed limits are "too
low". So, no, increasing enforcement of limits that are "too low" based on the
variance of speeds produced on those roads given _present_ enforcement
patterns helps safety in the same way as raising speed limits does, by
reducing speed variance. And it does so without increasing the number of
people who are driving faster than is safe for their own abilities because of
traffic pressure.

Now, you might argue that the cost of enforcement or the travel time make it
undesirable.

~~~
Sargos
Did you even read the article? Many speed limits are not based on safety,
which is the entire point of a speed limit. That's where "artificially low"
comes from. 85% of people drive at a safe speed regardless of what the speed
limit is. The speed limit should more closely match that safe speed.

Forcing everyone to drive at a slower speed than what's safe by force does not
actually make the road safer. 100% enforcement of current speed limits would
not actually make things better.

~~~
dragonwriter
> Did you even read the article?

Yes, and I directly addressed it's points. Did you read my post? Because you
don't seem to address what I've said, and you ignore that I've more directly
dealt with the points made in the article than you do in yours.

> 85% of people drive at a safe speed regardless of what the speed limit is.

No, traffic engineers have come to the conclusion that, because speed variance
is a significant source of risk, the safest speed limit (considering auto vs.
auto issues only) is the 85th percentile speed of traffic on the road, which
(at least with patterns of enforcement over the time the rule was found and
since) seems not to vary much based on posted limits, in any case.

That's​ the 85th percentile rule, and it's the single most common rule for
setting speed limits in the US. Its incorporated in federal guidance, its
incorporated in most state laws (though with some exceptions—e.g., school
zones, upper highway speed limits—in virtually all of them).

Given that the 85th percentile speed will rarely fall on exactly a convenient
numbee, you'd expect nearly half of limits to be below that because of
rounding, and add in some conditions which create downward departures in
limited cases, and, sure, as the article body says, most (>50%) are below. But
that's not the headline's "every speed limit".

Not is it clear, as I stated previously, that the 85th percentile rule is
ideal for safety for mixed use. There's considerable global evidence that
lower speed limits are better for that.

------
r0m4n0
I stumbled upon this presentation to local city leadership by the police
department
([https://youtu.be/BJNCCAJUEgM?t=9m36s](https://youtu.be/BJNCCAJUEgM?t=9m36s)).
The commentary by the police contradicts some of these facts from this article
but I would have to assume there is a vested interest in saying "pulling
people over more saves lives." There are likely many variables at play so its
hard to say what truly helps prevent accidents...

------
zw123456
I think Low speed limits are a source of revenue for a lot of cities.

------
takk309
This article makes it sound like 85th percentile speed is the one and only way
speed limits are set. This in not true. Often times, 85th percentile speed is
a starting point. Other metrics that come into play are pace and mode. The
pace of a traffic stream is defined as the 10 mph increment in speed in which
the highest percentage of drivers is observed. Mode is the most commonly
reported speed. Beyond these statistics based measure, roadside environment is
considered. The number of access points per mile, functional classification,
geometry, and traffic volumes are relevant when assigning speed limits.

There is very little benefit to increasing speed limits beyond the 85th
percentile. The capacity of the roadway does not increase because of the
increased headway between vehicles. As vehicles speed up, the distance between
vehicles increases and thus the total number of vehicles that can occupy a
given segment of roadway is decreased. At 30 mph, about 36 vehicles can fit
within a one mile stretch (assuming 3 second following distance, 15 ft long
vehicles and one travel lane). Under the same assumptions only about 16
vehicles would fit in a one mile section at 70 mph. However, slow speeds
everywhere is not reasonable and that is why some measure of central tendency
is used to establish speed limits.

~~~
u801e
> The pace of a traffic stream is defined as the 10 mph increment in speed in
> which the highest percentage of drivers is observed.

Doesn't the upper limit of that usually match the 85th percentile speed of
traffic?

> There is very little benefit to increasing speed limits beyond the 85th
> percentile.

Assuming traffic speeds follow a normal distribution, even those who exceed
the 85th percentile speed don't exceed it by much (more than 5 mph). Beyond
that, we're talking about 97th percentile speed or greater.

> As vehicles speed up, the distance between vehicles increases and thus the
> total number of vehicles that can occupy a given segment of roadway is
> decreased. At 30 mph, about 36 vehicles can fit within a one mile stretch
> (assuming 3 second following distance, 15 ft long vehicles and one travel
> lane). Under the same assumptions only about 16 vehicles would fit in a one
> mile section at 70 mph.

As traffic volume increases, the overall flow speed decreases which should
offset the issues you noted.

------
atemerev
I don't know what is the problem with speed limits in the US.

Here in Switzerland (and throughout Europe), most limits are mostly sane. We
have 120 km/h (75 mph) global highway limit, which you mostly don't want to
ignore (especially in the mountains, which is like almost anywhere). And on
the smaller roads, if it suddenly says e.g. 80 km/h, you better reduce your
speed, otherwise you'll risk not fitting into the turn.

------
ajmurmann
The last few days have been really interesting to me in regards to speed
limits. I grew up in rural Germany moved to the US west coast ten years ago.
However, I've been spending the last week on vacation in rural Ireland. At
first the speed limits here struck me as insane. Super narrow roads where I
was terrified to pass any cars coming my way out of fear of hitting them or
the wall to my left. Yet the speed limit is frequently 100km/h(60mph) and it
only changes in proper villages. If there are just a few houses on the side of
the road it still stays at 100. I was terrified on my first to days if driving
here (the whole driving on the left thing didn't help really either). After a
while I recalled that that's really how it worked in rural Germany as well
when I learned driving. Frequently the speed limit will be really high, much
higher than you could actually drive. However, there is trust that drivers
know how to drive a car safely given the conditions they can observe. Very
interesting and different approach.

------
monktastic1
Wait a minute.

> 85% of drivers drive at or below the speed limit. ... > “I’ve found that
> about 10% of drivers truly identify the speed limit sign and drive at or
> near that limit,” says Megge. Since these are the slowest share of drivers,
> they don’t affect the 85th percentile speed.

If 85% of drivers drive at or below the speed limit, then why are the 10% who
follow the speed limit amongst the slowest of drivers?

~~~
ubernostrum
85% drive at or below _in an ideal 85th-percentile-posted-limit situation_. In
reality, posted limits are rarely even close to the 85th-percentile speed of
traffic.

------
Al-Khwarizmi
“We all speed, yet months and months usually pass between us seeing a crash,”
Lt. Megge tells us when we call to discuss speed limits. “That tells me that
most of us are adequate, safe, reasonable drivers. Speeding and traffic safety
have a small correlation.”

So the standard for acceptability is that you only see a crash (i.e. a tragic
event, often with fatalities) every several months?

According to [https://www.cdc.gov/vitalsigns/motor-vehicle-
safety/](https://www.cdc.gov/vitalsigns/motor-vehicle-safety/) "more than
32,000 people are killed and 2 million are injured each year from motor
vehicle crashes. In 2013, the US crash death rate was more than twice the
average of other high-income countries." With that data, I don't know how a
post that starts by saying this even gets this high in HN.

Car travel is more than one order of magnitude more unsafe than train travel,
and two orders of magnitude more unsafe than plane travel. I think our
grandchildren will wonder how people in our time were so crazy to drive around
so much in cars, just as we now wonder how they were so crazy some decades ago
to watch nuclear tests live or hold asbestos shoving competitions.

As for the argument of the overwhelming majority of people not obeying limits,
I don't know the laws in the US but I suspect it may be relating to not fining
enough. It used to be the same way in Spain until they introduced more fines
the possibility of taking "points" off your license, which you lose for six
months (and it's cumbersome to get back) if you get to zero. Now most people
follow the limit or only drive slightly over it (there is a certain tolerance
level below which there are no fines) and when some years ago it went
temporarily from 120 to 110 km/h in highways, it was very visible how most
people were indeed driving slower.

~~~
hvidgaard
What is even more concerning, we have evidence[0] that raising the speedlimit
results in more fatalities, irrespectable of the 85th percentile.

In Denmark we raised the highway limit from 110kmh to 130kmh on half of all
highway. In the 2 years before and the 2 years after (ignoring the initial 2
months) the number of accidents and injuries on all roads fell roughly -15%.
But on the highways with the new limit, it increased with 14%, and the average
speed barely changed. The parts of the road where the 110kmh limit is saw
significantly less accidents as well, probably because the average speed here
decreased.

But the conclusion is fairly straight forward. The average speed barely
increased, but the number of accidents rose significantly.

[0]
[http://www.vejdirektoratet.dk/DA/viden_og_data/publikationer...](http://www.vejdirektoratet.dk/DA/viden_og_data/publikationer/Lists/Publikationer/Attachments/93/130km_paa_motorveje_rap337.pdf)

------
deanCommie
Everyone bringing up how things are in different countries from Switzerland to
Germany needs to stop it.

There are fundamental differences in the way people in different countries
approach driving and nothing's going to change that.

Swiss and Germans LIKE FOLLOWING RULES. It makes them happy (source: I work
with a lot of both and they will frequently make statements like "Rules exist
for a reason. If everyone just followed them the world would be better for
all." Yes, I jump straight to Hitler with my counterarguments)

Americans do not. To an extreme detriment to their own health and safety (see:
Airbag regulations that assume Americans won't have their seat belt on - a
basic prerequisite to driving for literally everyone else on the planet. See
also: socialized healthcare being "controversial").

------
wyager
Near where I live, there is a split 3-lane-each-way toll road. The speed limit
is 85mph.

Directly on either side of the toll road are the free roads. The only
difference is one fewer lane each way. The speed limit is 60mph.

I do not believe there is enough difference between the two roads to justify a
25mph speed limit difference, except to create an artificial police-enforced
incentive to fork over if you want to be able to drive as fast as you should.

I suspect many speed limits are designed in this way: either mostly arbitrary
or calculated to maximize revenue (for police, toll road operators, etc.).
They are not designed with optimizing driver utility in mind.

There are few things better than when you end up driving in a swarm of
experienced drivers who are willing to safely exceed the speed limit. Safety
(and efficiency!) in numbers.

~~~
rplst8
This is essentially what the DC region has with Virginia's Express lanes,
though the difference here is only 10 MPH.

The waste of space and resources that was required to put those extra lanes
in, and all of the traffic control measures could have EASILY doubled the
number of lanes on the beltway - alleviating traffic for many many years to
come.

Instead, they've just created a false economy around the pricing of
convenience. It's essentially rent seeking by the government.

~~~
aeorgnoieang
> alleviating traffic for many many years to come

This never seems to happen in practice tho, from what I understand. Traffic
always seems to 'magically' expand to match capacity.

~~~
rplst8
Because the highways have never been big enough in the first place.

------
carc1n0gen
I'm of the opinion that most people are just in too much of a hurry. I like to
leave early, take my time and do the limit when possible. I get better fuel
economy that way.

I still find myself speeding up to match the flow when the roads are busy
though.

------
MichaelBurge
> This is why getting slow drivers to stick to the right lane is so important
> to roadway safety

Can you be prosecuted for driving at the speed limit in the fast lane? It
seems like nobody would be legally allowed to use that lane if that were the
case.

~~~
username3
Driving the speed limit in the left lane is legal.

John Nestor tested the law in D.C. He was the major force in bringing to light
the effects of Thalidomide in the early 1960s. He stood up to drug companies.

> A plot was hatched, fueled by indignation: "By God, I've paid taxes for a
> long time -- and more than a lot of those trucks." First he consulted with
> the commonwealth attorney's office and other traffic authorities to ensure
> that his plan was legal, that passing on the right was acceptable on
> multilane highways and that traveling over 55, even to pass, was against the
> law.

[https://www.washingtonpost.com/archive/lifestyle/1984/11/21/...](https://www.washingtonpost.com/archive/lifestyle/1984/11/21/john-
nestor-strife-in-the-fast-lane/177dbb31-aeed-499e-8be4-9de519efd37a/)

------
post_break
There is a 7 lane road where I live, no residential houses on it. Speed limit?
45 mph. Cops sit on the other side of a small bridge and run radar all the
time. It's a joke since everyone does the "safe" speed limit of 55.

------
geggam
Surprised no one linked the Montana Paradox

[https://www.motorists.org/press/montana-no-speed-limit-
safet...](https://www.motorists.org/press/montana-no-speed-limit-safety-
paradox/)

------
godelski
So I've driven around a fair amount of the US. Has anyone noticed that
practically EVERY highway, people drive 70-80 mph. Regardless of the posted
sign. I wonder if anyone knows why it is specifically that range.

~~~
verytrivial
I know this will be unpopular with libertarian streak on HN, but if this is
the case, I think _every_ driver should be fined, or _every_ speed limit
should be raised if safe to do so. People should NOT be picking and choosing
which limits they think apply to them. If you want to drive like a maniac, buy
your own private road. Keep away from me and my family. (I don't mean _you_ in
particular, dear poster!)

~~~
godelski
>>If you want to drive like a maniac...

The whole point of this article was that driving those speeds isn't driving
like a maniac. Because if that is the flow of traffic the maniac thing to do
is drive at the speed limit.

------
peterjlee
In S.Korea, you never see a cop on the highway. They just have speed cameras
on accident prone zones and put up camera warning signs miles ahead so people
actually slow down. It seems pretty effective.

~~~
amlozano
They tried speed cameras with warning signs on the highways in Phoenix,
Arizona. They also had mobile vans with automatic cameras to catch people that
weren't paying attention. The population mostly refused to pay the tickets and
used every legal means available to dispute them, from ignoring the letters
until served to fighting the tickets in court. Some people wore masks so the
photos couldn't prove they were driving. Others did some shenanigans like
registering the car to a cooperation which somehow couldn't get a traffic
ticket (not sure that really worked). Still others installed reflective glass
that would obscure their license plate when the flash went off (though that
was quickly made illegal).

I also believe it came out that the company providing the cameras was getting
a cut of every ticket issued, leading to a tendency towards false positives.
The program wasn't profitable for the state and people complained so much that
the cameras were gone a short time later. I remember most people would slam on
the brakes just before the stationary cameras, cruise through at exactly 64 or
74 mph (the cameras went off at 10 mph above the posted limit) and then
accelerate to whatever speed they wanted. It was way worse than people just
speeding.

Maybe it works well in S. Korea because the incentives aren't so screwed up,
but here in the States "Cameras" mean someone is getting a cut and the people
are getting screwed. The camera's get set up in the best places to get revenue
(downhill when the speed limit changes from 65 mph to 55 mph around a bend so
you don't even see the sign before it's too late).

------
mark_l_watson
It is probably true that following too closely and careless lane changes are
more dangerous than going slightly over the speed limit.

That said, in addition to safety, cars get lower gas mileage at higher speed
(above about 50 mPH). Every time I see someone speed, follow too closely, or
is careless in lane changing, I think "there goes a selfish a$$hole who
doesn't care about the safety of others or the environment." I have never had
a speeding ticket, BTW. People who speed and drive carelessly are self
centered a$$holes.

------
AdamN
Weak article - nothing really about driving on other country's roads (Germany
is an excellent example). In Germany, the autobahn is unlimited speed but in
other areas, it's quite strict and every zone has a speed limit sign and then
when that limit is over, it's the same number with a slash through it (i.e.
the end of that rule). Like everything else, the US has so much to learn.

.... although the yellow stripe between opposite directions of traffic is
something the rest of the world sorely needs.

~~~
0xfeba
...and right on red after a stop!

"The United States' _only_ contribution to the modern world" to paraphrase
Jeremy Clarkson.

------
rand77763
Fucking obviously they are too low. Everyone knows this. Absolutely no one
drives exactly the speed limit. Speed limits are low to increase revenues from
speeding tickets.

------
rtpg
This topic comes up, and people really love the "people don't follow the speed
limit", but I remember seeing a couple studies that were very explicit. Places
raised the speed limit, and fatalities spiked upwards.

People focus on whether the speed limit will be respected and not on what the
full consequences up.

(Right now I can find a couple studies, but they're mostly from... insurance
lobbyists? I feel like the interests are aligned there but lobbyists so...)

~~~
ubernostrum
In a vacuum, the safest speed to be driving is one close to that of other
traffic around you. Outside of some specific situations (sharp curves, ice on
road, etc.), absolute speed does not cause accidents: speed _differential_
causes accidents, and does so in both directions. In other words, a car
traveling significantly faster than surrounding traffic is a danger, but so is
a car traveling significantly _slower_ than surrounding traffic.

The intuitive explanation is to consider that every instance of passing or
being passed is an opportunity for a collision, and increasing the number of
instances (either by being faster and passing many vehicles, or by being
slower and being passed by many vehicles) will inevitably catch up to you the
longer you do it.

Meanwhile, there is a _lot_ of well-done research around this. But several
factors get in the way of doing the ideal thing (which is usually to put the
speed limit either at the design speed of the road segment, or at the 85th
percentile of observed traffic speed). The biggest problem is political forces
causing a road to have a posted limit significantly lower than its design
speed; many people will, unless they're laser-focused on the speedometer, end
up driving around the design speed of the road regardless of posted limit,
because they'll take their cues from the road (width, length of curves, length
of turning and merging lanes, etc.) rather than from infrequently-placed
signs.

------
erodommoc
Of course, this is all based on a single study from the 1960's (Solomon,
David, "Accidents on main rural highways related to speed, driver, and
vehicle"), which has been pretty thoroughly debunked
([http://casr.adelaide.edu.au/ruralspeed/RURALSPEED.PDF](http://casr.adelaide.edu.au/ruralspeed/RURALSPEED.PDF)).

------
linuxhansl
According to
[https://en.wikipedia.org/wiki/List_of_countries_by_traffic-r...](https://en.wikipedia.org/wiki/List_of_countries_by_traffic-
related_death_rate)

Germany: 4.3 deaths/100k inhabitants, 6.8 deaths/100k vehicles.

United States: 10.6 deaths/100k inhabitants, 12.9 deaths/100k vehicles.

~~~
flukus
Deaths per billion vehicle-km:

Germany: 4.9 US: 7.1

I'd say that's a more reasonable measure.

------
derefr
So, given that this is how speeds get set, I'm guessing truly driverless cars
will completely break this paradigm by more rigorously adhering to the posted
limits? (They don't right now, instead following the flow of traffic, but they
might start once an autonomous-car maker gets sued for their algorithm getting
someone a speeding ticket.)

------
exabrial
The biggest problem is following distance... 100mph is safe on the highway if
you have enough distance to safely stop

------
JulianMorrison
I wonder what the impact on this will be when a significant minority of cars
are self-driving and _do_ stick to the speed limits? Unlike humans they won't
be persuaded by what the other drivers are doing - will the human drivers have
to slow to accommodate them?

------
booli
This comment will probably drain in the mountain of comments but:

I had this wonderful experience in the south of Portugal, where they had
traffic lights that would only go on red if you were speeding, and if you
would ignore the red light you would get a fine for it.

I thought it was pretty genius.

------
zten
This is a good article with sensible rationale for raising the speed limit on
freeways. It starts to touch on why local safety advocacy groups push for
lower speed limits, but it only really addresses speed in the context of other
motorized traffic.

------
wffurr
"If every car sets its cruise control at the same speed" I wish cruise control
use was more common on the highway than it appears to me, at least in eastern
Massachusetts. I don't want to play passing games; I just want to leave my
cruise control set at the speed limit.

Instead, many people seem content to do a bad job modulating their speed with
the pedal on hills, and average just under the speed limit instead; or swerve
like a maniac across as many lanes as it takes to get ahead a few car lengths.
It's really frustrating.

~~~
jonknee
Adaptive cruise makes highway driving so much less stressful. You don't even
notice the small changes in speed. It's becoming pretty popular and will soon
be standard on even lower end cars.

~~~
brewdad
My wife's car has ACC. I typically set it for about 6-7 over the limit on the
freeway (about 85% speed here). Every now and then I will suddenly realize
that I'm now going 50. Usually about the time some car flies past my in the
left lane and I'm wishing for some traffic enforcement. Then I see that he was
really only going the speed I planned to go and I've settled in behind a slow
poke.

------
dsfyu404ed
Bookmarked. Not because I don't know all this, but so I have something to cite
to when you jerks forget it all sometime next week...

------
nvarsj
Why not just put speed limiters in cars? I feel like this is a technological
problem that could be solved with enough effort. Install a GPS in every car
that speed limits based on road. Require GPS updates at the yearly MOT/smog
check.

------
amptorn
The speed of light is definitely too low.

------
FussyZeus
I just wish I could get tickets electronically and paid monthly. I'll pay the
stupid fine, just don't pull me over and waste my time.

~~~
jackhack
It's not just the ticket. It's the whole legal machine spinning up and
siphoning a pile of money off of you:court costs, lawyer/legal fees, auto
insurance increases for the next x years. And as you've mentioned, time away
from productive work.

The ticket is only a small part of the actual costs.

And even worse, while this combination-punch can be irritating to middle- and
upper-class folks, it can be financially devastating to someone living on the
edge of sustainability.

But then, somebody has to pay for all those shiny new Police Intercept
cruisers, SUVs, tactical body armor, new weapons & training, drones, robots,
etc. etc. etc.

~~~
FussyZeus
How about a $200/mo subscription plan where I get to go as fast as I want? I'd
get on board with that. :D

~~~
Neliquat
Have you heard the steve jobs approach? Ethically dubious, but very effective.
He just got a new car long enough he could avoid having a real plate so he
could park illegally.

~~~
jackhack
I don't think it was that deep -- I think Jobs was simply being a self-
absorbed asshole in this case.

I've not read of him routinely buying new cars - quite the contrary. In this
case I believe it was a simple disregard for the laws that only applied to
"little people." He couldn't be bothered and didn't care.

Related: He routinely parked his Mercedes (the one without a license plate) in
a reserved Handicapped parking space.

source: Walter Isaacson's Jobs biography, Sculley's book, and Amelio's book on
his time at Apple.

------
microcolonel
85% seems a bit just-so, I would bet they could find a more empirically-sound
number; but a good start I guess.

------
dragonwriter
A perfect example of Betteridges Law (and a very clickbait title): no, _every_
speed limit is not too low.

The article implicitly accepts the conventional 85h percentile rule as
defining correctness, and it's the single most common rule used to set speed
limits in the US. Yes, some are below because of rounding rules, and some are
below because of special safety conditions (in California, in general, these
allow 5mph downward departures), because of specific legislative exceptions
(school zones), or because of state maximums (which mostly affect major
highways, not city streets).

And, outside of restricted-access highways, while the 85th percentile rule may
be ideal _for automotive traffic alone_ , there's a reasonable case that it's
_too high_ for mixed uses. [0]

[0] An example of the argument is here:
[http://la.streetsblog.org/2016/06/15/legal-obstacles-to-
safe...](http://la.streetsblog.org/2016/06/15/legal-obstacles-to-safe-streets-
california-speed-limit-laws/)

~~~
vacri
There's also the issues of roads being _designed_ to be traveled at a certain
speed; the limit needing to suit all traffic, including heavy vehicles; and
the limit needing to be somewhat suitable for poor weather, because some
people don't actually drive to the conditions, especially when the conditions
are marginally poor.

------
mdip
Michiganian here ... I've watched the speed limits increase over the last few
years on all but residential roads and though my take is anecdotal, it's a
fantastic thing as far as I'm concerned.

I used to drive 62 miles round trip to work, worked at home for a bit in
between and am now back to about a 30 mile round-trip commute. Both were split
equally on surface and freeway roads. Back when the speed limits were lower it
was generally expected that most drivers -- during rush hour (assuming one
could reach the speeds) -- would drive 50 MPH in a 40 and around 55 in a 50.
It always surprised me -- every morning and evening on about a 6-mile stretch
of road marked 40 MPH, there wasn't a car driving under 50 (and when that rare
driver arrived, he was often tailgated so hard that traffic safety decreased
considerably for him). Then, out of the blue, almost every road I took to work
was changed to 50 MPH. Surprisingly, people weren't suddenly driving 60 MPH.
I'm now on a similar commute as I was years ago, taking that same road, and
people are consistently driving between 50 and 55 MPH on it.

I love our 85th percentile rule. It makes sense -- that one driver who's
obeying the speed limit is being tail-gated by everyone else, reducing the
distance between him and other cars, which increases accident probability and
the relative severity of the accident since it will happen at a higher speed
due to reduced braking time. When everyone is going about the same speed on
the road, cars tend to be more spaced out and the relative difference in speed
between the two objects colliding affects the severity of the accident.

There's also a lot of misconceptions about how speed is enforced -- at least
in my area -- and what rules exist around speeding. I'm not sure if this is
still the case, but it used to be that you were legally allowed to exceed the
speed limit by 10 MPH on a freeway to overtake a vehicle in the passing lane.
I have family who work in traffic patrol for the county and this topic comes
up regularly. The department they work in encourages targeting people driving
in excess of the speed of traffic, not folks who are keeping up with the speed
of the cars around them. Of course, you _can_ be pulled over in this scenario,
and you _are_ breaking the law[0], but at least in my area, it's not
encouraged. An orderly system is safe, an outlier is unsafe, so they aim for
folks who are driving in the left lane on a freeway in low traffic volumes,
folks going over 20% of the speed of others and exceeding the speed limit,
people jumping solid lines[1] and the huge problem caused by large numbers of
people running red lights and failing to yield right-of-way when turning
left[2].

[0] Both of them will tell you "If I want to pull you over, I can find a
reason". A common one is those plastic covers/dealer advertisements around
license plates or things hanging from a rear-view mirror. Some of the plate
variations are legal (but there are _very_ specific rules and almost all of
them are not -- it's just rarely enforced), but most things hanging from the
rear view mirror are obstructions.

[1] There are many places on the freeways in Michigan where the lane markers
are solid white and for some reason, people don't understand that it's illegal
to change lanes -- that's why they're solid. Aside from safety (they're put in
due to increased blind-spots that make lane changes unsafe), they're often
located in areas where people are entering the freeway and backups occur.
Folks who panic at merging traffic or just don't want to slow down will jump
lanes ... causing a worse backup.

[2] I realized this is going to sound uncommon to folks who don't live here,
so pardon the long explanation. _Easily_ the most common issue on road-ways in
my area is people failing to yield when turning left at an intersection (my
cousin/uncle will tell you this, but if you live here you're either already
aware of the problem, or you aren't realizing you're doing it). Red light
running is also more common here than in most of the country because of the
frequency with which people encounter one-way intersections. It's legal,
everywhere (except NYC and a probably a few other corner cases), to turn
_left_ on red when the road is one-way. Where I live, every road over three
lanes (and many under) are engineered using the "Michigan Left"
([https://en.wikipedia.org/wiki/Michigan_left](https://en.wikipedia.org/wiki/Michigan_left)).
Often, though becoming less common, the "turnaround" is configured so that you
can only turn left onto the same road heading in the opposite direction.
Everything's fine when this is the case. However, it's grown popular to
position these turnaround lanes in places that coincide with large retail
business entrances or moderate traffic side-roads. All bets are off here.
Because people are used to turning left on red in these turn-arounds, they
assume they can also, legally, go straight into the side-road/business on red.
Go ahead and google for signs telling people _not to run red lights_ ... I
couldn't find any. We have _several_ of them on Hall Road in Macomb County.
People are also used to "just going" when it's green, but you can't do that if
the turnaround has traffic entering the road on the other side -- all of that
traffic is turning right and has the right-of-way, just like in any other
intersection -- left _must_ yield unless they have a green arrow. I've been
_honked at_ on more than a few occasions by other drivers for not just plowing
into the intersection, or not running the red to enter a side-street when
traffic is clear but the light is red. Worse, once they put these hybrid side-
street/turnarounds in, it destroys any advantage that the Michigan Left
supposedly provides. It's already at a disadvantage since a portion of the
traffic now has to pass through an intersection twice, but now the advantage
of the "increased flow due to reduced traffic light phases" is overcome by the
backups occurring in _both_ turnarounds bleeding into a lane of traffic and
the sudden pouring in of _new_ traffic -- which has priority over existing
traffic due to right-of-way -- entering in from popular businesses and busier
side-streets (and, yes, a vein is popping out in my forehead now).

------
douche
Yup, the good old federal highway funding, the stick that keeps the states in
line. Also why we have the absurd and harmful drinking age of 21.

~~~
24gttghh
Too low or too high?

~~~
graphitezepp
Far too high. If I recall correctly there is heaps of evidence that lowering
the age decreases alcohol abuse in populations long term.

------
xiphias
This is totally American way of thinking. Just look at other countries, like
Switzerland where the death rate is 3x lower per person: make sure that every
car takes the law seriuously and put drivers who drive 2x faster to prison.

Not seeing a person dying in an accident in the last couple of months is not a
good enough excuse for me. Even the fact that I know 1 person in my life who
died in a car accident means that we should be stricter in law enforcement
with speed limits.

------
rdxm
With traffic fatalities back up at levels not seen in something like a decade
due to inattentive drivers, the last thing we need is more speed.

What we need is autonomous vehicles, because the sad truth is that a very
large portion of the driving population should never have been issued a
license in the first place.

Don't even get me started on the 85th percentile thing. That is a poster child
for lazy engineering and government.

~~~
u801e
> With traffic fatalities back up at levels not seen in something like a
> decade due to inattentive drivers

Do you have a citation for the increase being caused by inattentive drivers?
There could be other factors, such as more people driving instead of flying,
for instance.

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Neliquat
My right foot and sticky tires say yes.

But I do wish everyone would just drive to their abilities rather than some
prescribed upper limit. Our laws made sense back when you still found
carriages on the road. (Sorry Amish).

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et-al
Unfortunately you're asking people to gauge their own driving abilities. And
it's known that most people are overconfident in their abilities.

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Neliquat
Yes, my comment was equally serious and tounge in cheek.

As I mentioned in another comment, I would love to see an advanced driver
certification available. My main gripe with the common driver is their being
unaware of the fundamental shift in car handling above 50mph, countersteering
with loss of traction, and tire condition.

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et-al
I was going to suggest different driver classes as a tongue in cheek solution.
Because Americans would love more rules. ;)

