3 votes

MRL - Clark Fork River Bridge No. 3


Photo taken by Garrett Boon in April 2011


BH Photo #196927


Street View 


Bridge over Clark Fork River on Montana RailLink
Sanders County, Montana
Built 1908, Reinforced date unknown
- Burlington Northern Railroad (BN)
- Montana Rail Link (MRL)
- Northern Pacific Railroad (NP)
Length of largest span: 166.0 ft.
Total length: 452.0 ft.
Deck width: 18.0 ft.
Approximate latitude, longitude
+47.32178, -114.89216   (decimal degrees)
47°19'18" N, 114°53'32" W   (degrees°minutes'seconds")
Approximate UTM coordinates
11/659281/5243077 (zone/easting/northing)
Quadrangle map:
Keystone Peak
2566 ft. above sea level
Inventory number
BH 45430 (Bridgehunter.com ID)

Update Log 

  • April 5, 2018: New photos from Richard Doody
  • March 21, 2018: Updated by John Marvig: Added Build Date from NP Bridge Book
  • June 2, 2017: Updated by Christopher Finigan: Added categories "Pin-connected", "Riveted"
  • October 8, 2013: Updated by Luke Harden: Added categories "Railroad", "Montana Rail Link"
  • April 8, 2011: New photos from Garrett Boon
  • May 31, 2010: Added by Craig Philpott



MRL - Clark Fork River Bridge No. 3
Posted August 20, 2015, by Nathan Holth (webmaster [at] historicbridges [dot] org)

Tim, its based off a patented supplemental arch system invented by Jai Kim as shown here http://www.google.com/patents/US4691399

MRL - Clark Fork River Bridge No. 3
Posted August 20, 2015, by Tim Nordstrom (tim [dot] nordstrom [at] comcast [dot] net)

Thanks for the photos.

It could be called a Pratt Deck Truss with Bow-String retro-fit.

Clark Fork Railroad Bridge #2
Posted October 8, 2013, by Jim Lueken (lueken [at] bellsouth [dot] net)

These 'supplemental' arch members were a very clever way to add strength and capacity to the original trusses while keeping the original members intact. Congrats to those reponsible!

Clark Fork Railroad Bridge #2
Posted April 9, 2011, by Anthony Dillon (spansaver [at] hotmail [dot] com)

Yup.....that's what I would call it Craig.

I wish the Madison Railroad in Southern Indiana would do this to their deck trusses instead of demolishing them.

Clark Fork Railroad Bridge #2
Posted April 8, 2011, by Craig Philpott (cphilpott [at] puc [dot] edu)

Interesting modification and mixture of forms. So now, what type of span is this? Pratt Thru Truss with supplemental Arch?

Clark Fork Railroad Bridge #2
Posted April 8, 2011, by Garrett Boon

You will notice some changes in the recent photos I took and the Google Stree View. They've been working on this bridge adding an arch in the truss.