

Crashmapper: Visualizing Years of Traffic Collisions in NYC - talos
http://blog.accursedware.com/introducing-nyc-crashmapper/

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salmonellaeater
Obligatory XKCD: [http://xkcd.com/1138/](http://xkcd.com/1138/)

In Seattle a few intersections have been singled out as the most dangerous for
cyclists because of the number of collisions involving cyclists there.
Considering they are also the highest-traffic intersections for bicycles, it
doesn't actually say anything about how dangerous they are per cyclist-trip.

Crashmapper is useless without knowing how many vehicles pass each
intersection per day.

~~~
milliams
However, if you want to use it to know where to focus efforts to save the most
lives it is useful. It's the correct representation for some uses, just not
for all uses.

~~~
jvm
Although even in that case it's important to know both pieces of information.
Past some level of safety, intersections likely hit a floor where no amount of
further investment will actually make them safer.

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brownbat
> Past some level of safety, intersections likely hit a floor where no amount
> of further investment will actually make them safer.

That point is probably called "driverless cars."

~~~
seanmcdirmid
And "driverless cycles" probably also.

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RobotCaleb
I learned that pretty much every corner has crash potential. :)

We ran into a similar problem at my last job. I mapped crash locations in our
game to the map in which they took place. When viewed in aggregate it ended up
turning into more of a map of where people tend to congregate in the game then
where problem spots actually exist.

~~~
undantag
We did something similar and actually ended up finding a confusing hotspot.
Turned out to be a ledge where people could clip through a fence and fall to
their deaths.

~~~
RobotCaleb
That's not to imply it wasn't helpful. Just that once we knocked out all of
the low-hanging fruit the map turned into an indication of where people
played. Remaining crashes weren't related to location or content.

The first pass actually had a nice grid pattern on the map that was where
ambient audio emitters happened to overlap. Something about the transition
between two ambients emitters was falling over.

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pixie_
This is a good example where some color would really help.

There are points with the same color where their collision count is different
by a factor of 10.

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jessriedel
Comment on style: The transparency of the orange heat spots should not fall
below 30% or so, even at the center. Having the heat spots opaque makes the
map difficult to read.

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aggronn
Huh. I worked at a place that had access to data similar to this, but
statewide and in a different state. I wanted to put something like this
together, but i was told the data was very sensitive and that I couldn't get
access to it, since knowing that some intersections are really dangerous opens
up government agencies to lawsuits for not fixing them.

So its interesting to see this here.

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eterm
I like how on error he redirects to the application to serve custom urls
giving a dual meaning to crash mapping.

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Quai
I've done something similar for Oslo, Norway;
[http://trafikk.quai.io/](http://trafikk.quai.io/) (warning: Norwegian text)

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jweir
Great start!

It would be wonderful if you could enter a time span, rather than seeing one
month at a time.

Maybe filter by daylight/nighttime hours?

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danso
It's worth pointing out this historical context mentioned in the OP's Github:

> _Council Member Jessica Lappin got into an animated discussion with Petito
> over traffic crash data. When Lappin asked why NYPD is releasing data in PDF
> form — and only after the council adopted legislation forcing the department
> to do so — Petito replied that the department is "concerned with the
> integrity of the data itself." Petito said NYPD believes data released on a
> spreadsheet could be manipulated by people who want "to make a point of some
> sort." An incredulous Lappin assured Petito that the public only wants to
> analyze the data to improve safety, not use it for "evil."_

This is a persistent problem in public records law: officials who are asked to
provide public data in computer parsable formats but instead, deliver it as
PDFs or worse, as paper printouts.

The reason given by the NYPD is so common a trope that it's hard to say that
they're just technically slow. When you consider that the NYPD has taken
strong criticism for not investigating fatal accidents seriously, it's
reasonable to suspect the NYPD of actively obfuscating when they use the "oh
but they'll alter the spreadsheets!"

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dragonwriter
Digitally-signed spreadsheets are a thing. If concern about altered versions
was the real issue, there are mitigations that don't remove the utility of
having a consumable data format. Its not merely "reasonable to suspect" that
refusal to give usable formats is motivated by desire to make it more
difficult to use the data rather than concern about alterations, it is almost
unreasonable to believe anything else.

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badmadrad
for a second i thought this was mapping ethernet packet collisions and i
thought it was cool but couldn't figure out why we would need a heatmap

