Is Every Speed Limit Too Low? - <AUTHOR> https://priceonomics.com/is-every-speed-limit-too-low/ <comment><USER4> 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.

<comment><USER5> 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.

<comment><USER6> 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.

<comment><USER7> 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?

<comment><USER8> 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.

<comment><USER9> What makes a road a 25mph road? One dangerous enough that people don't feel comfortable driving faster -- how is that a solution?

<comment><USER10> 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.

<comment><USER11> 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).

<comment><USER12> 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)

<comment><USER13> 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.

<comment><USER14> > 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.

<comment><USER15> Hanging bars seem to solve this problem. Makes a loud terrifying noise when you hit them, but doesn't leave any permanent damage.

<comment><USER12> 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.

<comment><USER16> 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.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER17> 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.)

<comment><USER18> 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.

<comment><USER19> 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.

<comment><USER20> > 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.

<comment> 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?)

<comment><USER21> 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.

<comment><USER22> 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.

<comment><USER23> 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...

<comment> 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.

</comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER24> 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.

<comment><USER25> And, potentially, pull you over for complying with the speed limit if the normal rate around you is large. Either way, you could lose.

<comment><USER26> 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.

<comment><USER27> 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.

<comment><USER28> Source? AFAIK, encryption has never been illegal in the US. Export of encryption was, but currently is in a reasonable state.

<comment><USER27> 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.

</comment></comment></comment></comment></comment></comment><comment><USER29> 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.

<comment><USER30> 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.

<comment><USER31> 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?

<comment><USER30> 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.

</comment></comment></comment></comment><comment><USER32> 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 - <USER2> 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.

<comment><USER33> 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.

<comment><USER34> 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.

</comment></comment></comment><comment><USER35> 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.

<comment><USER36> 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.

<comment><USER37> 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)).

<comment><USER38> 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.

</comment></comment></comment></comment><comment><USER39> 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.

<comment><USER40> >while also removing the revenue incentives for police.

Well that will never happen..

</comment></comment><comment><USER41> 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/)

<comment><USER42> 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)

<comment><USER43> 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.

<comment><USER42> 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.

<comment><USER44> Plenty of US states have small populations, no? Also lots of states are comparatively homogeneous (Sweden has 19% of population as recent immigrants).

<comment><USER42> 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.

<comment><USER44> > natural resources as a economic base

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

</comment></comment></comment></comment></comment></comment></comment><comment><USER45> 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.

<comment><USER46> 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.

<comment><USER47> 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.

<comment><USER48> But why? I understand 25mph just fine. 23mph is only going to distract me.

<comment><USER49> 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

<comment><USER48> 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.

</comment></comment></comment></comment></comment></comment><comment><USER50> 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)

<comment><USER51> > 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.

<comment><USER52> 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.

<comment><USER51> IIRC it's still like 30-40 % higher when considering distance.

</comment></comment></comment></comment><comment><USER53> 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.

<comment> 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...

<comment><USER54> 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.

</comment></comment></comment><comment><USER55> 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.

<comment><USER56> 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.

<comment><USER57> > 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.

</comment></comment></comment><comment><USER58> 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,+email@example.com,2.7...](https://www.google.com/maps/place/A5,+firstname.lastname@example.com,2.7953364,12z/data=!4m5!3m4!1s0x47ee948c507acd09:0x3c978e6c3b47deb9!8m2!3d48.2729269!4d3.8765452)

<comment><USER59> 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".

<comment><USER60> 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.

</comment></comment></comment><comment><USER61> 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.

<comment><USER62> 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.

<comment><USER63> How many people are injured or killed annually by motor vehicles traveling on sidewalks?

<comment><USER64> I think you meant to put this into a Google search, not a comment.

</comment></comment></comment></comment><comment><USER65> 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.

<comment><USER46> 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.

<comment><USER66> 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.

<comment><USER67> 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.

</comment></comment></comment></comment><comment><USER68> 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.

<comment><USER69> 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.

<comment><USER70> 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.

<comment><USER46> 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.

<comment><USER47> 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.

</comment></comment></comment></comment></comment><comment><USER71> 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.).

</comment><comment><USER72> > 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.

</comment><comment><USER73> 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.

<comment><USER74> You're not bothering anyone if you stay to the right (assuming US) so they can pass.

<comment><USER62> 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.

<comment><USER75> Staying out of the passing lane when not passing someone is actually the law in many states. You must keep right if able.

<comment><USER76> 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.

<comment><USER77> 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.

<comment><USER78> > 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.

</comment></comment></comment></comment></comment></comment></comment><comment><USER79> 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.

<comment><USER80> 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).

<comment><USER55> That's the German approach actually. There is no speed limit on some of the highways, yet the recommended speed is 130 km/h.

</comment></comment></comment><comment><USER81> 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.

<comment><USER82> > _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.

<comment><USER83> Average speed cameras are a solution to that problem and frequently used for long-running road works on UK motorways.

<comment><USER49> 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

<comment><USER83> 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.

</comment></comment></comment></comment></comment><comment><USER84> 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.

</comment><comment><USER70> 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.

<comment><USER85> 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.

</comment></comment><comment><USER86> "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

<comment> 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.

<comment><USER87> I'm not surprised that someone with a psychopathic desire to inconvenience people would seek employment in government bureaucracy.

<comment><USER77> 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/)

</comment></comment></comment></comment><comment><USER88> 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.

<comment><USER89> The point of this article is that often, speeding is _safer_ than obeying the speed limit. In those cases it seems moral to speed.

<comment><USER90> 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.

<comment><USER24> 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.

<comment><USER88> 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.

</comment></comment></comment></comment></comment><comment><USER91> 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/)

<comment><USER46> 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.

</comment></comment><comment><USER92> 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).

<comment><USER92> 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.

<comment><USER78> 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.

</comment></comment></comment><comment><USER93> > 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.

<comment><USER75> 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.

<comment><USER94> > 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.

<comment><USER75> 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.

<comment><USER94> > 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.

</comment></comment></comment></comment></comment><comment><USER95> 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...

</comment><comment><USER96> I think Low speed limits are a source of revenue for a lot of cities.

</comment><comment><USER97> 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.

<comment><USER78> > 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.

</comment></comment><comment><USER98> 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.

</comment><comment><USER99> 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.

</comment><comment><USER100> 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?

<comment><USER76> 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.

</comment></comment><comment> 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.

<comment><USER38> 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)

</comment></comment><comment><USER101> 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 - <USER3> basic prerequisite to driving for literally everyone else on the planet. See also: socialized healthcare being "controversial").

</comment><comment><USER87> 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.

<comment><USER62> 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.

<comment><USER102> > 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.

<comment><USER62> Because the highways have never been big enough in the first place.

</comment></comment></comment></comment><comment><USER103> 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.

</comment><comment><USER104> > 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.

<comment><USER77> 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/)

</comment></comment><comment><USER105> 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.

</comment><comment><USER106> 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/)

</comment><comment><USER107> 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.

<comment><USER108> 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!)

<comment><USER107> >>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.

</comment></comment></comment><comment><USER109> 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.

<comment><USER110> 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).

</comment></comment><comment><USER111> 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.

</comment><comment><USER112> 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.

<comment><USER113> ...and right on red after a stop!

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

</comment></comment><comment><USER114> 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.

</comment><comment><USER115> 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...)

<comment><USER76> 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.

</comment></comment><comment><USER116> 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)).

</comment><comment><USER117> 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.

<comment><USER118> Deaths per billion vehicle-km:

Germany: 4.9 US: 7.1

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

</comment></comment><comment><USER119> 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.)

</comment><comment><USER120> The biggest problem is following distance... 100mph is safe on the highway if you have enough distance to safely stop

</comment><comment><USER121> 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?

</comment><comment><USER122> 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.

</comment><comment><USER123> 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.

</comment><comment><USER59> "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.

<comment><USER124> 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.

<comment><USER47> 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.

</comment></comment></comment><comment><USER125> 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...

</comment><comment><USER126> 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.

</comment><comment><USER127> The speed of light is definitely too low.

</comment><comment><USER128> 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.

<comment><USER129> 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.

<comment><USER128> 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

<comment><USER46> 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.

<comment><USER129> 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.

</comment></comment></comment></comment></comment><comment><USER130> 85% seems a bit just-so, I would bet they could find a more empirically-sound number; but a good start I guess.

</comment><comment><USER94> 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/)

<comment><USER131> 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.

</comment></comment><comment><USER132> 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).

</comment><comment><USER133> 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.

<comment><USER134> Too low or too high?

<comment><USER135> Far too high. If I recall correctly there is heaps of evidence that lowering the age decreases alcohol abuse in populations long term.

</comment></comment></comment><comment><USER136> 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.

</comment><comment><USER137> 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.

<comment><USER78> > 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.

</comment></comment><comment><USER46> 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).

<comment> 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.

<comment><USER46> 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.

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


The secret world of microwave networks - <AUTHOR> http://arstechnica.com/information-technology/2016/11/private-microwave-networks-financial-hft/ <comment><USER2> [https://sniperinmahwah.wordpress.com/](https://sniperinmahwah.wordpress.com/) is the best resource I've ever seen for learning about these networks and the rationale behind their construction.

</comment><comment><USER3> Previous discussion: [https://news.ycombinator.com/item?id=12862789](https://news.ycombinator.com/item?id=12862789)</comment>