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GRNW - Clearwater River Bridge


BG&CM - Clearwater Bridge


Photo taken by Douglas Butler


BH Photo #286254


Street View 


This now inoperative swing bridge consists of two Whipple-Pratt side spans joined together by a center tower, with overhead tension ties to support the side spans when the bridge was swung.

Per the below referenced NP bridge book, the swing span is a 238' through Pin Connected Truss(TPCT) installed in 1916. It is flanked by a pair of 75' through Plate Girders(TPG), with a 6-panel pile trestle(PT) on the north side and an 11 panel pile trestle on the south side, all installed in 1951. Total length was 726'. Since other bridge book examples imply a 15' standard trestle panel, at least 6 panels were double length. Photographs suggest 2 on the north side and 4 on the south, all in the deep water adjacent to the TPGs.

The swing span is a circa 1880 product of the Phoenix Bridge Works, with their characteristic Phoenix patent wrought iron tubular posts used for most compression members. The source of this recycled span is not currently known, but one possibility is the NP's original bridge over the mouth of the Snake river at Ainsworth, opened in 1884. The UP also had a swing bridge over the Snake at Riperia, opened in 1888, but that span had distinctly different trussing. See Thomas Winpenny's "Without Fitting, Filing or Chipping"(1996) for a history of the bridge works, and Hal Riegger's "The Camas Prairie"(1981) for local railroad history.


Whipple-Pratt through truss swing bridge over Clearwater River on Great Northwest Railroad
Kamiah, Lewis County, Idaho, and Idaho County, Idaho
Open to traffic
Est. 1880's construction, original location unknown, installed 1916
- Phoenix Bridge Co. of Phoenixville, Pennsylvania
- Bountiful Grain & Craig Mountain Railroad (BGCM)
- Camas Prairie Railroad (CSP)
- Northern Pacific Railroad (NP)
Pin connected Whipple-Pratt through truss swing bridge.
Length of largest span: 238.0 ft.
Total length: 726.0 ft.
Also called
BG&CM - Clearwater River Bridge
Kamiah Swing Bridge
Approximate latitude, longitude
+46.24102, -116.03770   (decimal degrees)
46°14'28" N, 116°02'16" W   (degrees°minutes'seconds")
Approximate UTM coordinates
11/574188/5121276 (zone/easting/northing)
Quadrangle map:
1140 ft. above sea level
Inventory number
BH 56584 (Bridgehunter.com ID)

Update Log 

  • January 20, 2020: New photo from Geoff Hubbs
  • June 20, 2019: New photo from Adam
  • January 15, 2019: Updated by John C Stutz: Expanded description, in anticipation of loading detail photos.
  • September 9, 2018: Updated by Fmiser: added length and description
  • June 23, 2014: New photo from Douglas Butler
  • June 12, 2013: Added by Luke Harden

Related Bridges 

  • Hayden Bridge (Same design) - A simple pin connected Whipple-Pratt through truss, of similar date and design, by the same builder. Very extensivly documented, with a link to an HAER report.



GRNW - Clearwater River Bridge
Posted June 26, 2020, by Luke

In case any of ya'll want to blow almost $2,000 on a already-built version of the brass model: https://www.ebay.com/itm/HO-BRASS-OMI-CAMAS-PRAIRE-STEEL-SWI...

GRNW - Clearwater River Bridge
Posted January 31, 2020, by John Marvig (marvigj27 [at] gmail [dot] com)

My luck going through NP records has came to a screeching halt with the three major truss bridges on this line. The most I can currently find on this one is that the approaches were originally supposed to be 155' Through trusses from Yellowstone Division, 3rd Subdivision. However, this improvement was cancelled in 1914. At that time, the Whipple did show up in drawings, deepening the mystery.

GRNW - Clearwater River Bridge
Posted September 1, 2019, by Luke

While looking for information on the Camas, Washington wagon bridge, Google served me up a listing for an HO scale brass model of this bridge, which features amazing detail of the Phoenix columns and portals.


GRNW - Clearwater River Bridge
Posted September 10, 2018, by John Marvig (marvigj27 [at] gmail [dot] com)

According to this Northern Pacific bridge book:


The truss was built here in 1916, indicating it was likely relocated. Could it be possible that this was originally a stationary span built elsewhere in the 1880s, and moved here?

GRNW - Clearwater River Bridge
Posted September 9, 2018, by Fmiser (fmiser [at] gmail [dot] com)

Karl - Thanks for the history!

I saw this bridge through the trees as I was driving west on US12 - but time and my long trailer prevented me from stopping and exploring. My research since make me really regret that I didn't try harder to get to it.

I found a stock photo here:


That, plus my memory and Douglas's drawing provided the data for the sketch I added. The sketch is probably not dimensionally accurate, but it shows the unusually construction.

BG&CM - Clearwater River Bridge
Posted June 5, 2014, by Karl Strauss (straus8 [at] ca [dot] rr [dot] com)

This is a swing bridge over a non-navigable river. When the Clearwater River Railroad wars were taking place, the Northern Pacific and Oregon-Washington Railroad and Navigation (OWR&N) were racing towards the Kamiah region with its bountiful forests and just as bountiful fields of grain. The first one there would grab the honeypot. The NP was winning the war but the OWN&R had an upper hand. They convinced a judge that the Clearwater river (average depths of some 6 feet) was navigable and also that it was of such quality that a steamboat could navigate it, and therefore a bridge - an expensive movable bridge was necessary per US law.

In the spring thaw the river does indeed become a raging torrent and the OWN&R folks knew this. On a spring day they convinced the captain of a sternwheeler based in nearby Lewiston, rumored to be a notorious drunk, to make the run to Kamiah on dare. And he took up the challenge. With Judge and Jury on hand the steamboat made its one and only entry into Kamiah and the judge ordered that a movable bridge be built.

The motor mechanism is long removed and the rails welded close but the large bull gear remains.