
Why do we keep designing streets for speed? - gscott
https://www.strongtowns.org/journal/2018/1/25/speed-kills-so-why-do-we-keep-designing-for-it
======
lsh123
Speed limits in US highways had been introduced in 70s to save gas during the
crisis. Let’s all agree it had nothing to do with safety.

The claim that 30% of incidents are caused by speeding are also questionable.
Few years back I was rear ended by someone talking on the phone. The officer
wrote speeding as the cause of incident. When I asked about it, he replied
that the safe speed in this case was zero. Just wander how many of these 30%
are the same.

P.S. I rarely actually go above the speed of the traffic flow. I think it is
the safest to drive at the same speed as others even if it is above speed
limit. On the other hand, drivers in the left lane going 60 mph when everyone
else is doing 85 mph are the real danger on the road.

~~~
KozmoNau7
I've found it much more relaxing to just drive the speed limit, keep to the
right as much as possible and to be a courteous driver in general.

I let the traffic flow around me, instead of trying to keep up with everyone.
When I'm driving, I relax and try not to stress about getting to my
destination as quickly as possible.

YMMV of course, as I'm in Europe and driving habits do differ a lot.

I think inattentiveness and impatience are the biggest killers in traffic. I
don't really care if people are going 10 over, as long as they're not
harassing other people.

~~~
int_19h
Hereabouts, if you drive in the right lane, you'll be stuck behind someone
going 5-10 mph slower than the posted limit.

(For what it's worth, it can also happen in the leftmost lane, just not quite
as often.)

~~~
KozmoNau7
And then you overtake those people, when an appropriate gap appears. Or you
exercise patience and wait.

~~~
int_19h
Or you could just move one lane to the left...

------
tallpapab
Interesting article. One can easily notice that most folks seem to treat the
speed limit as a minimum speed rather than a maximum speed. It's not just
designers designing for speed. They do so because of market demand. That
demand is boosted by advertising - both overt and culturally pervasive
imagery. Buckle up folks. Try not to speed. You're really not saving much, if
any, time. Also minimize left turns and lane changes. When you do turn (or
change lanes) always use your turn indicator. When cars are robots they can do
these things. The worry it that freedom loving consumers will still choose
thrills over safety and this may stunt the adoption of robocars.

~~~
bsder
Ah, yet another Strong Towns anti-car screed of "let's make all roads so damn
slow nobody can actually get anywhere" without any discussion of the
_downside_ of what they propose.

I've lived in "Cannah get theyah from heah" Boston. I can assure you that
slow, safe, crappy, narrow, winding roads suck as bad as you think.

Or try going from Braddock to Penn Hills in Pittsburgh, PA. Nice and slow and
infuriating. There's a reason why a whole bunch of people decided "You know,
that nice empty area west of Pittsburgh with roads that actually let you get
from A to B is very enticing."

> One can easily notice that most folks seem to treat the speed limit as a
> minimum speed rather than a maximum speed.

I disagree. People simply _IGNORE_ the speed limit and drive at what they
consider to be a safe speed.

Part of the problem is that there are political forces ( _cough_ police
budgets) that encourage stupidly low speed limits. If all roads were set at
the appropriate speed (something like 85% of traffic, IIRC, but there is an
actual engineering number), suddenly "speeding" becomes an actual traffic
safety issue.

And, in fact, ignoring a speed limit is a rational decision when everybody
else would be going 10-20mph faster than you. Absolute speed means more damage
when a accident occurs, but _relative_ speed differentials mean more
_accidents_ occur.

~~~
Piskvorrr
Didn't read? That 85% _mantra_ is mentioned. Yes, it's an engineering
principle...designed for rural roads. Blindly applying that to all other road
types is not engineering, that's cargo cult.

~~~
snowpanda
Can someone please explain the 85% thing to me? I've read both the comments
and article and still don't fully understand what it is. Maybe I'm stupid.

~~~
TeMPOraL
Not 85%, but 85th percentile, apparently.

[https://metrocount.com/downloads/flyers/Speed_analysis_1.pdf](https://metrocount.com/downloads/flyers/Speed_analysis_1.pdf)

I'm not a traffic engineer so I'd love an explanation, because on the first
look, it seems absurd to apply this measure to determining speed limits, as a)
85th percentile will keep creeping up with each iteration of such speed limit
adjustment, and b) the whole rationale seems to depend on "wisdom of the
crowds", i.e. trusting greedy optimization to find the right balance in the
system that needs to be optimized _globally_.

~~~
u801e
> a) 85th percentile will keep creeping up with each iteration of such speed
> limit adjustment,

That doesn't actually occur. In 1997, West Virginia raised its speed limits
from 55 to 65 mph on limited access 4 lane divided highways. The 85th
percentile speed incrased from 62 mph to 66.5 mph. The compliance level with
the speed limit went from 15% to nearly 85%. On interstate highways, the speed
limit increased from 65 mph to 70 mph. The 85th percentile speed increased
from 70 mph to 71.6 mph. The compliance rate went from 50% to about 70%.

In both cases, the compliance rate went up (in one case, substantially). Also,
the Martin Parker study [1] also says that lowering and raising speed limits
do not substantially affect actual traffic speeds.

[1] [https://www.ibiblio.org/rdu/sl-
irrel/index.html](https://www.ibiblio.org/rdu/sl-irrel/index.html)

------
boznz
Quite an interesting article.

My beef is also with car manufacturers. I have a bog standard 2015 Mazda 3.
The speedometer reads up to 260KMH, the national speed limit in the country is
100KMH, who the fuck are they designing these things for?

~~~
perl4ever
I have some thoughts on why this is the case.

First, speed limits vary from place to place and manufacturers don't need to
change the speedometer for each one. For instance, in the US, there are places
where the limit is as high as 137KMH, and it used to be unlimited in places. I
don't know what Germany is like these days.

Also, the Mazda3 is said to have a governed top speed of 190KMH* so the
speedometer reading up to 260 is a red herring with respect to actual
performance.

Finally, a high top speed is a side effect of having the acceleration that
consumers would like.

*It's a governed speed in order to preserve the tires, but it's unlikely it would make 260KMH even without the governor; maybe 200-220KMH at best - see [https://en.wikipedia.org/wiki/Mazda3](https://en.wikipedia.org/wiki/Mazda3)

~~~
robin_reala
Top speed doesn’t directly correspond with acceleration, as weight plays a
factor as well. To pick a slightly extreme example, Caterham’s Seven 160 will
accelerate from 0-60mph in 6.9s yet tops out at 100mph, due to a sub-500kg
weight and an 80bhp engine:
[http://uk.caterhamcars.com/cars/seven-160](http://uk.caterhamcars.com/cars/seven-160)

~~~
perl4ever
Implicitly I was referring to a given car model, which isn't going to have
that much variation in weight.

------
closeparen
>However, a majority of the severe injury and fatal collisions are
preventable, so they are not accidents

100% of transportation-related incidents are preventable, full stop. You can
always stay home. Beyond that, it's a question of how we balance a number of
factors such as risk and quality of life.

~~~
frobozz
Also, where does the author get the idea that preventable is an antonym of
accidental?

Just because someone failed to take certain steps to prevent an accident, it
doesn't mean that they deliberately caused the accident.

~~~
amputect
I've got a guess as to what the author is talking about, because gun owners
have a similar thing. In the case of guns, it's "there's no such thing as an
accidental discharge, only a negligent one".

By this reading, the author is probably saying that unless your car
malfunctions and prevents you from stopping or steering, or there is some
equivalent fluke happening (a deer darts out in front of you and you
physically can't stop in time), then "accidents" are caused by negligence (not
checking lanes when changing, playing with the radio, not looking for
pedestrians) or malfeasance (unsafe passing, driving at an unsafe speed for
the conditions, drunk driving).

I have mixed feelings about this, but I've been driving a while and I've seen
a lot of truly stupid and/or mean spirited and/or reckless behavior that could
quite predictably result in a collision, but it'd be a stretch to call the sad
and obvious outcome an 'accident'.

~~~
frobozz
It then goes on to say

> What is your state or city doing to address this safety issue and prevent
> severe injuries and fatalities?

So the negligent party is implied not to be the individual driver who is not
giving due care and attention, but the road designer or maintainer for not
making the road safer.

I agree that crashes often occur due to the direct negligence of a road user,
but when it comes to the state, there are a lot of tradeoffs and calculations
to make. They are not responsible for each individual accident, but for the
overall outcome of road use in general. It's erroneous to say the state is
negligent for (e.g) funding emergency services to improve outcomes after a
range of incidents both on and off the road, vs. Road safety measures. If £X
of extra ambulance and fire funding prevents Y road-related deaths and Z other
deaths, whilst that same sum on road safety measures only prevents those Y
road deaths, then cure may be better than prevention.

------
Animats
Japan runs with somewhat lower speed limits.

The article is heavy on Celebration, FL, which was built by Disney, but has
fallen on hard times. It's deliberately retro idealized 1950s America, and
entirely privatized. That's a very unusual community.

The optimal speed for maximum traffic flow is around 35mph. Faster than that,
and the cars space out further and throughput decreases. Slower than that, and
not enough cars per second are passing. Metering signals are designed to
throttle entry to the freeway to keep speed around 35mph.

~~~
mikekchar
Living in Japan, I'm not sure I would say that the slower speeds make things
safer (can't say one way or another). However, it _definitely_ changes the way
you think about geography.

I spent about 12 years of my adult life living in Ottawa Canada and about 8
years living in Japan (with the balance being in the UK). In Ottawa, I would
not think twice about driving 20-30 km to hang out with my friend after work.
When all is said and done, it's under an hour of driving for a round trip. But
in Japan, 30 km away might as well be on the other side of the moon for me
most days. From where I live, the nearest "big" city (of 700K people) is 25
km. To drive there would take over an hour each way. The bus fare is over $20
US, round trip (and takes 3 hours round trip).

I stay in my town. I walk to the izakaya (neighbourhood pub). I walk to the
super market. I walk to the hardware store. I walk everywhere -- anything I
would want to go to is less than 2 km away.

Not everybody lives the way I do, but enough people do that each town has it's
own flavour. It has it's own special foods and shops. I can ride my bike 5 km
to the next town over _and it 's different than the town I live in_. I can go
another 5 km and _that town is also different_.

Compared to Canada, it's night an day. In Canada, it would take me 5 km just
to get out of my housing subdivision. Walking to the grocery store is a crazy
thought unless you just happened to live next to a grocery story. Don't get me
wrong -- Ottawa is a great place, but you really need to live in the older
areas to get much flavour. The rest is cookie cutter subdivisions,
interspersed with malls.

Having said that, I'm not sure if it's reasonable to expect to transplant a
non-car culture into NA. The vast majority of my friends in Canada dream of
owning a home with enough land that they never have to see their neighbours.
They don't _wan 't_ a neighbourhood where they walk everywhere. They want a
kind of island and they really don't mind driving from island to island. It's
not for me, but I can definitely understand the appeal.

~~~
mantas
> They don't wan't a neighbourhood where they walk everywhere. They want a
> kind of island and they really don't mind driving from island to island.
> It's not for me, but I can definitely understand the appeal.

That's interesting. Sometimes it feels like "modern city" advocates are super
extrovert narcissists who want everyone to live in crammed spaces with many
people around. And then optimise for that. They're willing to sacrifice space
for their needs

Yet many people legitimately want to live sparsely and are willing to
sacrifice other things for space.

~~~
mikekchar
That might be a kind of extreme position, but I think you're right that they
would be looking for slightly higher population densities in general. In Japan
it's kind of forced on people because the country is so mountainous. You only
have so much flat space to work with and you have to balance the needs of
living, farming and manufacturing. People who want to live all by themselves
can move up into the mountains where you are basically surrounded by nature.

For me, I live in a small town. There are about 20K people in this area,
although the official city is quite a bit bigger (it encompasses 3 towns and
the intervening mountains for efficient administration purposes). I live in an
apartment building, but that building is literally in the middle of a rice
field. The whole town is a mix of farms, tea fields, manufacturing plants
(including some very famous ones, even though we are in the middle of nowhere)
and houses. Even though a lot of people refer to this town as being sh*t rural
(literal translation -- kuso inaka), it actually has a population density of a
typical suburban neighbourhood in North America. Even with that population
density, I can walk for 20 minutes or so and be in a nature preserve where
nobody lives.

This is pretty typical here. Farms are small. People live in towns and
villages that are fairly tightly packed and surrounded by mountains. Even in
fairly large cities (say around 700K or so), it won't take you more than about
15 minute of walking from the inner city to hit your first farm.

I know a lot of people love big city life, but I'm not one of those people. I
like living in a neighbourhood that is self contained and has a local flavour.
I like knowing my neighbours and seeing them daily as they walk or bike to
work (again fairly unique Japanese culture -- most people never change jobs,
so they can easily live near their workplace). Even more, I like travelling
and exploring my surroundings because there is something interesting in every
nook and cranny. Ironically, the difficulty in travel and the geographical
separation of towns makes it possible to to "travel" 10 km and be a tourist.

I personally think that the people advocating the "modern city" are on the
right track, even if I don't always agree on everything. However, I can
understand why it is a hard sell in Canada and the US (I shouldn't lump in
Mexico here, because I know nothing about it).

~~~
mantas
It's a hard sell not only in Canada or US, quite a bit of Europe has more than
enough space as well. "Modern city" is good you want to optimise for dense
living and certain lifestyles. Yet it fails for quite a few people and then
quite a bit of it doesn't make sense. I guess the solution would be to design
cities to allow both kinds of people to leave at peace. Personally I like
German model. Dense urban centers with liveable country side. Looks like both
kinds of people are pretty happy and they can sustain quite a lot of
population too.

------
icc97
It's not just speed it's the distance that you keep. If everyone kept to the 3
seconds rule, which basically applies at any speed we'd all be safer. Further
you simply increase that when there's ice and rain.

France has broken white stripes along side their motorway with gaps every 4
seconds travelling at 80 mph. It's beautifully simple and saves on paint too.

~~~
tehlike
One of the most important rule we tend to forget.

Distance and less variance in traffic speed.

------
mlazos
The one issue I have with the article is that the author doesn’t mention
specifics about designing streets to lower the speed. Is the implied
suggestion to make roads terribly curved so it’s really hard to drive fast?
That seems to have it’s own drawbacks. I was surprised the author didn’t
mention that many cities have intersections designed so that cars trying to
turn right with a green light often intersect with a crosswalk that is also
green for pedestrians. That seems more amiable to redesign rather than the
grid road designs favored in most cities.

~~~
sparrc
I believe the author is advocating for "traffic calming" measures, which are a
fairly standardized set of measures that urban planners and developers use to
slow down traffic on streets to make them safer. See
[https://en.wikipedia.org/wiki/Traffic_calming](https://en.wikipedia.org/wiki/Traffic_calming)

------
kaplun
... because speed is... fun? :-)

------
mathgeek
> a majority of the severe injury and fatal collisions are preventable, so
> they are not accidents

They are indeed accidents, using the definition which implies unexpectedness
(rather than the definition which implies chance).

------
jwatte
Because wasting time on transpiration also kills, small slices of lost life in
parallel.

Traffic had long hanging fruit for saving lives for sure -- mandatory daytime
running lights come to mind as a zero cost improvement -- but the speed
equation is not generally simple.

~~~
KozmoNau7
>Because wasting time on transpiration also kills, small slices of lost life
in parallel.

So you're willing to put other people at risk, for an immeasurable gain to
yourself?

Maybe you should take public transport more, where you can actually do
something else while being transported?

~~~
dang
> _So you 're_

Comments here need to follow the HN guideline which asks: "Please respond to
the strongest plausible interpretation of what someone says, not a weaker one
that's easier to criticize."

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

~~~
KozmoNau7
Based on my experience with other people, both in and out of traffic, that
_is_ the most plausible interpretation.

~~~
dang
That's not what the guideline is asking for. If it were, it would be a no-op,
since that would be asking for one's first interpretation, and we get that
anyway.

~~~
KozmoNau7
"Assume good faith" is a tall order, when you have to deal with people
everyday.

------
Mo3
Inadequate drivers kill, not the speed.

~~~
KozmoNau7
Inadequate drivers go too fast for their own skills.

Adequate drivers know that speed does kill, or at least makes accidents much
worse. They are not overconfident fools.

 _Good_ drivers know the rules of the road and follow them, they know when to
bend them, and when _not_ to bend them.

Speeding isn't worth it, you gain a minute here or there, that's it.

------
CamperBob2
It's a shame that statistics don't back up this hoary old saying. Turns out
that modeling drivers as if they were ideal gas particles doesn't give you the
numbers you expect.

Meanwhile, lack of respect for traffic laws due to inappropriately-low speed
limits arguably does get people killed.

~~~
TeMPOraL
> _Meanwhile, lack of respect for traffic laws due to inappropriately-low
> speed limits arguably does get people killed._

This is one area where I believe we need to treat the "lack of respect" part,
i.e. beat the people into submission. Because it's not reasonable to optimize
speed limits for what a driver feels should be appropriate - a driver takes
into account his own position and situation only, while optimizing traffic is
a much larger-scale exercise.

(Also, frankly, it's the speed that kills. If either the pedestrian or you
were dumb enough to get into crash at 50km/h, you'd get into an _even harder_
crash at 100km/h. I cringe when I hear drivers wanting to raise speed limits
on the roads that have foot traffic crossing it, children playing on the
sidewalks, etc.)

~~~
mantas
German autobahn traffic would like a word with you. Drivers over there are
pretty good to find out their reasonable speed. There's a ton of respect
between drivers too. Probably the most respectful driving culture I drove at.

~~~
konschubert
Aside from the fact that the parent was talking about city streets, not
freeways...

I find Autobahn driving very stressful. Crossing the border into Switzerland,
which has a general speed limit, traveling becomes much more enjoyable.

~~~
mantas
I was talking about his general sentiment that people don’t consider others
and have to be beaten into submission.

Out of countries I drive at, Germany is least stressful. Especially because
drivers seem to be very considerate of others. Including, if not more, on
unlimited autobahn sections.

Haven’t driven in Switzerland yet though.

~~~
TeMPOraL
> _I was talking about his general sentiment that people don’t consider others
> and have to be beaten into submission._

It's not that they don't consider others (though there are plenty of angry
drivers out there). It's that they're _assuming_ they know better than traffic
engineers and legislators. That assumption is full of hubris, and _even if_
sometimes correct, it makes it more difficult for people setting the limits to
do global optimization. But yes, ultimately it is - maybe unintentionally -
not considering other users of the road system.

~~~
CamperBob2
_It 's that they're assuming they know better than traffic engineers and
legislators_

I think it's very safe to say I know better than legislators who've never been
within hundreds of miles of the road I'm driving on.

It may not be as safe to say I know better than the engineers, but the
engineers' opinions are of very little interest to the legislators.

