2013 Chicagoland Bike Map is distorted

While waiting for the snow to melt, I've been looking at my new Chicagoland Bike Map from the Active Transportation Alliance.

What was the ATA thinking?  They have published a map that is badly distorted, not drawn to scale.  The purported scale is 1" on the map equals 1.5 miles on the ground. That scale holds true for the North-South dimension, but not for the East-West dimension.  

Take any known mile and a half distance in a north-south direction, say Addison to Lawrence.  That measures 1" on the map.  Now pick a known mile and a half distance in an east-west direction.  Say Kedzie to Damen.  That measures almost  1-5/8" on the map.  

And it's like that everywhere.  Take a known mile square.  Say from Lincoln-Belmont-Ashland to Lincoln-Fullerton-Halsted.  Belmont to Fullerton is a mile, Ashland to Halsted is a mile.  On any other map, Lincoln Ave. between these two points is a 45 degree angle.  Not on this map.  The Belmont-Ashland-Fullerton-Halsted square is a rectangle with a ratio of 8:5 instead of 1:1.

What bizarre kind of map projection is this?  Did the ATA cartographers have to yield to the ATA graphic designers, who decided to junk the aspect ratio to fit the planned size of the map?

This should not have happened.

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Permalink Reply by Steve Cohen on March 7, 2014 at 9:33am

Yes, I can confirm that from my days as a Chicago cabbie.  800 to a mile is golden on the Northside, on the South Side south of 31st and everywhere East-West.

S said:



Mike Zumwalt said:

What's with all the measuring?

The grid is every 800 in numbers equals a mile and every destination has an address.

That's not true.  Madison to 31st has some odd numberings, e.g. Roosevelt is a mile south of Madison but is 1200 S.   But in general 800 to a mile is accurate and as far as I know, it's accurate in the east-west direction. 

Permalink Reply by Active Transportation Alliance on March 7, 2014 at 9:48am

Thanks for bringing this problem to our attention. We didn’t realize it until now, but we see the map was somehow stretched in the east-west directions, which resulted in a distortion of the scale.

It looks like an error was introduced at some point in the process of handling the map files. We’re truly sorry for the error.

We’re looking into it and trying to pinpoint where the problem occurred so that it won’t happen again. Until we discover exactly where it occurred, we can only guess that it was introduced into one of the many versions this map underwent.

There’s a huge amount of work that goes into creating a new edition of Active Trans’ Chicagoland Bike Map, so any error like this is a big disappointment for us.

One of our goals for this map was to enhance information about regional routes and connections. We’ve had a lot of good feedback on the map in the past year on these features and others. We still think the map is very useful in helping people get around the region via bike.

Again, we’re very sorry for the error and want to assure you that we’re looking into the problem.

Regards,

Ted Villaire

Active Trans, director of communications

Permalink Reply by Andrew Bedno on March 7, 2014 at 9:56am

Sorry Steve, I meant truthy as in credible, believable, and I'd hoped a PDF would exhibit the same problem.

Permalink Reply by Steve Cohen on March 7, 2014 at 10:00am

np

Andrew Bedno said:

Sorry Steve, I meant truthy as in credible, believable, and I'd hoped a PDF would exhibit the same problem.

Permalink Reply by Steve Cohen on March 7, 2014 at 10:06am

Thanks, Ted, for stepping up and admitting the mistake.

I will say that apart from this I like the map and its design in terms of color, etc.  It's quite easy to read.  I also like the improved paper stock.  

But this sort of error is hard for me (as a map geek) to accept.  And actually, even my original posting was a little in error.  The actual skew is more like 11:8 rather than 8:5 and Kedzie-Damen is more like 1-3/8" rather than 1-5/8"


Active Transportation Alliance said:

Thanks for bringing this problem to our attention. We didn’t realize it until now, but we see the map was somehow stretched in the east-west directions, which resulted in a distortion of the scale.

...

Regards,

Ted Villaire

Active Trans, director of communications

Permalink Reply by Mike Zumwalt on March 7, 2014 at 6:50pm

I still don't get it. If I'm planning a ride,drive or trip it's simple math it shouldn't involve a ruler. 

I'm at Halsted and North and need to go to Damen and Division. 2000-800 is 1200 so a mile and a half west. 1600-1200 is 400 so a half mile south.

I did most of my learnin' in Detroit and suburbs where they name roads after miles from the city even though the angle streets are actually further in distance than 8,9,10 miles...

Steve Cohen said:

What's with all the measuring?

Any map I've ever seen uses the same scale in both dimensions. Anyone trying to use this map and its purported scale to plot the distance of a ride will not get accurate results unless the route is strictly north-south. It may not be the most important thing in the world, but must all our technology continue to make us stupider by the minute?

I'm not sure this even qualifies as a "map". "Map-like graphic" would be more accurate. But it's sold as a map.
Permalink Reply by Joe Guzzardo on March 7, 2014 at 9:20pm

In layman's terms, this is a result of the relativistic effects of the spin of the Earth on its axis when superimposed orthogonally against the dilation of force vectors along the medial plane of rotation in the vortex of a Zeitgeist saturated gravitational field, nominally modulated for statistical differentials, of course. Happens all the time. I could get into the technical details but it would probably go over your head. Trust me, the truthiness is out there.

Steve Cohen said:

Actually, it's the map that's truthy.  :-)

Permalink Reply by Skip Montanaro 0mi on March 8, 2014 at 3:01am

peter moormann said:

Personally I love old maps.

Way off-topic, but my wife uses old maps as decoupage material on various bits of furniture and household accessories:

https://www.etsy.com/shop/OneYellowDoor

Bringing it back on-topic, to my knowledge she's never checked them for scale. :-)

Permalink Reply by Joe Guzzardo on March 9, 2014 at 5:10am

I spoke with a professor of geography once about the Piri Reis map. He said the map showed very accurate details of the Antarctic coast that lied below the ice glaciers in existence at the time. The map was drawn with knowledge not available at the time, which led to claims of extra-terrestrial origin. He had no explanation for this enigma. This a real life X Files type of mystery.

 
Skip Montanaro 12mi said:

peter moormann said:

Personally I love old maps.

Way off-topic, but my wife uses old maps as decoupage material on various bits of furniture and household accessories:

https://www.etsy.com/shop/OneYellowDoor

Bringing it back on-topic, to my knowledge she's never checked them for scale. :-)

Permalink Reply by Bill P on March 9, 2014 at 2:07pm

I applaud the effort, but think the objective was flawed.  Including so much area on single sheet was not necessary, and resulted in something physically much too large to be practical.  With a reduced scale (even if it were correct) for the dense area of the city where the detail is most important, I find it much less useful than prior editions.

Permalink Reply by Mike Schwab on March 10, 2014 at 12:19pm

COS(41 degrees) is .75.  So if it was set for 1 degree N/S = 1 degree E/W you would get E/W stretched by that percent.
 
Active Transportation Alliance said:

Thanks for bringing this problem to our attention. We didn’t realize it until now, but we see the map was somehow stretched in the east-west directions, which resulted in a distortion of the scale.

It looks like an error was introduced at some point in the process of handling the map files. We’re truly sorry for the error.

We’re looking into it and trying to pinpoint where the problem occurred so that it won’t happen again. Until we discover exactly where it occurred, we can only guess that it was introduced into one of the many versions this map underwent.

There’s a huge amount of work that goes into creating a new edition of Active Trans’ Chicagoland Bike Map, so any error like this is a big disappointment for us.

One of our goals for this map was to enhance information about regional routes and connections. We’ve had a lot of good feedback on the map in the past year on these features and others. We still think the map is very useful in helping people get around the region via bike.

Again, we’re very sorry for the error and want to assure you that we’re looking into the problem.

Regards,

Ted Villaire

Active Trans, director of communications

Permalink Reply by Mike Schwab on March 11, 2014 at 7:31am

I found this is called a cylindrical projection.

Mike Schwab said:

COS(41 degrees) is .75.  So if it was set for 1 degree N/S = 1 degree E/W you would get E/W stretched by that percent.
 

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