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First Carver Railroad Bridge

Photos 

First Carver Railroad Bridge

Photo taken from Carver Historical Sociaty

View this photo at pegnsean.net

BH Photo #242335

Map 

Description 

The first bridge built at this location in 1871, replaced in 1898

Facts 

Overview
Lost through truss bridge over Minnesota River on Former Minneapolis & St. Louis Railway
Location
Carver, Carver County, Minnesota, and Scott County, Minnesota
Status
Replaced by a new bridge
History
Built 1871 for the M&STL
Railroad
- Minneapolis & St. Louis Railway (M&StL; MSTL)
Design
Wooden Through truss with Pony Truss approaches
Dimensions
Length of largest span: 270.0 ft.
Approximate latitude, longitude
+44.76281, -93.62147   (decimal degrees)
44°45'46" N, 93°37'17" W   (degrees°minutes'seconds")
Approximate UTM coordinates
15/450817/4956789 (zone/easting/northing)
Quadrangle map:
Shakopee
Inventory number
BH 54257 (Bridgehunter.com ID)

Update Log 

  • September 24, 2018: New photo from Douglas Butler
  • November 1, 2012: Added by John Marvig

Related Bridges 

Sources 

  • John Marvig - marvigj27 [at] gmail [dot] com
  • Douglas Butler

Comments 

First Carver Railroad Bridge
Posted November 4, 2012, by Will Truax (Bridgewright [at] gmail [dot] com)

At first when I saw these yesterday, I thought it not improbable that this was a variant of McCallum's "Inflexible Arched Truss" with McCallum doing most of his work before during and after the war for Railroads, and with him partner or principal in a number of bridge companies which marketed almost exclusively to them.

Then a close look with magnification suggested there were rods and not wooden tensile members at the panel points, suggesting this was yes a Curved Top Chord Howe Knowing a bit about Wooden RR Howe's I thought this more than a little odd. It makes little sense for a one off of modest span, the added cost of the pattern making for the cast angle blocks just didn't add up...

Turns out it was not a one off, and with it being a Swing Span, chord length was controlled not by circumstance of channel width, but by necessity and design, and the patterns were likely used enough times to recoup the substantial cost of investment.

There is a brief history cited here - http://tiny.cc/hp68mw - which suggests another copy was built earlier the same year, and a really fine side view shot of the swing span.

First Carver Railroad Bridge
Posted November 3, 2012, by John Marvig (johnmarvig [at] chaska [dot] net)

To say the least, it was very interesting. The Carver historical society has a lot of photos of it that I hope to eventually receive copies of.

The bridge at Ft. Snelling was built by Milwaukee Road, and this bridge was Minneapolis & St. Louis. My understanding is that there was a similar design on the Milwaukee Roads crossing of the Minnesota River at Chaska when that bridge was first built in 1871.

The approaches are Howe, and the historian told me that, and I listed them correctly.

This bridge ranks among the ones I wish I could have seen...

First Carver Railroad Bridge
Posted November 3, 2012, by Matt Lohry

I just saw a photo in a book of the virtually identical Ft. Snelling swing bridge shown in its open position, and from what I can see, that bridge's main span appears to be a double-intersection Warren truss--I only say this because it seems to me that in order to be classified a Howe (or an "inverted" Pratt, relating to the earlier discussion regarding the Old Salt River Swing Bridge in Kentucky :)), the diagonal members in one direction would be doubled-up or reinforced, but that does not appear to be the case here. All of the diagonals are the same dimensions, and they are arranged in the double-intersection Warren configuration. I agree with Fmiser that the approaches are definitely Howe trusses.

First Carver Railroad Bridge
Posted November 3, 2012, by Fmiser (fmiser [at] gmail [dot] com)

Curious!

> Tony Dillon wrote:

> The only thing I can think of made of wood might be a tied arch of some type. The tied arch was basically the equivalent to a bowstring truss, but made from wood.

I'm going to get picky here. First, a tied arch is not limited to wood. All arches transfer vertical load to horizontal force at the arch springings. On a plain arch, this force is transferred to the abutment and typically the ground. A tied arch uses a tension member along the springing line to connect the two arch springings and thus balance the outward horizontal forces. Often the deck is suspended from the arch with tension members. I see tied arch bridges built mostly from steel.

A bowstring truss is a truss. While it looks a lot like a suspended deck tied arch, the bowstring truss diagonals are under tension, but the verticals are under _compression_ load. It behaves like a Parker truss, but with a continuous curve rather than a segmented, polygon top chord.

Subtle differences, and I am being picky. *smiles*

As for this bridge? The approach looks like a Howe truss. The arching span is obscured by the angle, so it's not clear what it is. From the shadows, it appears the diagonals are arranged like a Howe, but with a curved top chord. It also looks like it can't be a tied arch because the lower chord is below the springing line if the top chord were an arch - meaning it would'n work well as a tie. So maybe it's a Parker-like treatment of a Howe truss.

First Carver Railroad Bridge
Posted November 2, 2012, by John Marvig (johnmarvig [at] chaska [dot] net)

Perhaps a better side view is seen here

First Carver Railroad Bridge
Posted November 2, 2012, by Tony Dillon (spansaver [at] hotmail [dot] com)

The only thing I can think of made of wood might be a tied arch of some type. The tied arch was basically the equivalent to a bowstring truss, but made from wood. Unlike a Burr Arch that was used in conjunction with a multiple kingpost truss, the tied arch could stand alone. I am familiar with a few that were built in Ohio, but they were of older vintage having been built in the 1820's-30's.

It was definitely a unique structure!

First Carver Railroad Bridge
Posted November 1, 2012, by John Marvig (johnmarvig [at] chaska [dot] net)

Truss type anyone?