Large Scale Central

St. Paul 7th St. Improvement Arches

Track and Trestles
#1

OK technically not a RR project but it does span a RR. It was actually a highway project. It spanned the St Paul & Duluth Railroad and was completed in 1884. It as the coolest design. It is a skewed stone arch bridge. It is also made in what is called helicoidal design which is a fancy smancy word for spiraled. Apparently makes it strong as hell. You can read about it here but it is a damn neat bridge.

http://en.wikipedia.org/wiki/Seventh_Street_Improvement_Arches

This link is also good and has a pic in the day.

http://saintpaulhistorical.com/items/show/26#.VRmuleGM7W8

Here are some shots I took

Would be a kick to model. I guess it is a mathematical nightmare and the guy who designed it studied math as a hobby and he became famous among his peers for designing this. I would just scribe it into a piece of plastic. Much easier.

#2

Am I seeing what I think I’m seeing? The angles of the inside of the arch follow the angles of the arch itself? All the away around 180 degrees?

That’s sick. I’d love to give it a shot!

#3

John it is crazier than that. They aren’t just angled they are spiraled. and the blocks are trapezoidal and have a concave curve on the bottom. It seriously challenged the stone cutters of the day. I couldn’t get a good enough picture to do it justice. There are good ones online. It is an engineering marvel. He made it into the architecture hall of fame. There is technical data to be had on the net if you search.

#4

Here this shows the spiral.

here is a link to stuff that is technical

http://www.historicbridges.org/bridges/browser/?bridgebrowser=minnesota/7thstreet/#photosvideos

#5

one tunnel is 25 feet wide and the other 35 feet wide as I stepped it off so not exact. they say it is skewed 63 degrees relative to the track.

#6

John here is what you need to read to build it.

http://www.historicbridges.org/minnesota/7thstreet/articles.pdf

#7

And here I thought I over-designed some of my projects. That would give the stone cutters and stone masons fits. I mean, no stone on the inside is level.

#8

David,

Not only are they not level they are not square. Each block is cut with a twist.

This is a nightmare

#9

Devon, yes I got that. Now that I have vertigo, I think its time for a nightcap, then bed.

#10

David Maynard said:

Devon, yes I got that. Now that I have vertigo, I think its time for a nightcap, then bed.

The pictures don’t do it justice. You should have seen the three of us going “how’d they do that.” I sure am not smart enough to figure it out, even wit pictures (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-undecided.gif)

#11

WoW ! Many fantastic things were built back then. Thanks for posting, . . . . :slight_smile: