City of Cottage Grove

Chambers Covered Railroad Bridge

Chambers Railroad Bridge
The Chambers Railroad Bridge is the only remaining covered railroad bridge in Oregon.  It is believed to be the only remaining covered railroad bridge west of the Mississippi River.  The Chambers Bridge is a Howe Truss bridge (see explanation of a Howe truss below). 

The bridge was constructed in 1925 by lumberman J.H. Chambers to transport logs across the Coast Fork Willamette River to his sawmill on the east side of the bridge.  The bridge was in operation from 1925 to 1951.  In the 1950's the railroad was sold for scrap and the bridge was no longer used.  The bridge was in private ownership until December 2006, when the City of Cottage Grove finally secured full ownership of the bridge.  The bridge is listed on the National Historic Register (NRIS no.79002081).   Chambers Mill, 1940's Chambers Bridge
                          upper left corner

                Truss While in private ownership, no maintenance was performed and significant damage and decay occurred to the bridge.  The only reason the bridge remains standing today is because it wasInterior of Chambers Railroad Bridge constructed using oversized timbers to support the heavy loads of the steam locomotives and railcars loaded with logs.  The oversized materials used in the original construction of the bridge add significant cost to the restoration efforts. 

In addition to acquiring the bridge the City pursued the owners
hip of some property on the east end of the bridge.  As a result, sufficient property on the east end has been donated to the City for access and future development of a park.  Coupled with the Cityís current ownership of the land on the west end of the bridge full access and use of the bridge was secured.  The bridge when restored will be able to serve as an additional pedestrian and bicycle crossing on the Coast Fork Willamette River.
Decay on bridgge
In 2006 the bridge had experienced significant damage and decay and was leaning to the upriver side.  Concern existed that if restoration work is not begun quickly the historic treasure of Oregonís only remaining covered railroad bridge would be lost.

The Chambers Covered Railroad Bridge was awarded a $1,315,370 grant from the National Historic Covered Bridge Preservation Program.  The City provided a match of at least $136,000.   Additional funds were awarded from the American Recovery and Reinvestment Act and the Oregon Surface Transportation Program. 

The City began the Round Up for the Bridge program in February 2007 to provide an oppo
Chambers Covered Railroad Bridge east sidertunity for local citizens to contribute to the restoration project.  The program basically invites citizens to round up their Water/Sewer bills and the rounded up change goes to the trust fund established to fund bridge restoration.   Many citizens have taken the opportunity to round up for the bridge.  We have had some round up an additional dollar or two.  The largest round seen to date is a $20 round up.  The trust fund is established so that anyone can also donate into the fund to help with the bridge restoration and bridge park development.    As of February 27, 2009 we have raised through the round up program $7,790.  The funds raised will be used to help achieve the match needed for the National Historic Covered Bridge Preservation grant that we have received. 

The resconstructed bridge was moved back into place October 6, 2011.
Bridge moving across
People watching the
                        Chamber Covered Railroad Bridge move.
The Chambers Covered
                        Railroad Bridge in place
Chambers Covered Railroad back where it

Videos of the Chambers Covered Railroad Bridge

The restored Chambers Covered Railroad Bridge was dedicated and opened for public use on December 3, 2011.  Thank you to everyone who joined us for the celebration.  Check out the photos and video of the project on this page.

The reconstructed Chambers Covered Railroad Bridge was launched into position on Thursday, October 6th.  Following placement over the river the remaining work on the informational kiosk, concrete, roof and access will be completed.

For a time lapse video (1:28 minutes) made by OBEC Engineers click here.  The video shows the forklifts pushing the bridge into place.

Click on picture to see larger photo and information

Emergency Declared
On February 9, 2010 it was discovered that the Chambers Covered Railroad
Chambers Railroad Bridge - River Road
                        Portal Bridge had moved and creating additional leaning upstream.  Apparently the bridge had moved as a result of the January 12, 2010 storm.  The bridge was in danger of imminent collapse.  On Tuesday, February 16, 2010 the Cottage Grove City Council held an Emergency Council Meeting to declare an emergency and authorize the immediate dismantling of the bridge.  Upon adoption of the emergency resolution the City and consulting engineers (OBEC) began securing approvals from State and Federal agencies for the dismantling of the bridge.   Clearances were received Friday, February 19, 2010 and onsite work began Monday, February 22, 2010.

Bridge Dismantling
Bridge dismantling began February 24, 2010.  The bridge was secured and a substructure under the bridge was built to stabilize the bridge during the dismantling.  A platform was built on the downstream side of the bridge and rolled under the bridge.  Once under the bridge the platform was raised to hold the bridge structure in place.  The upper chords were anchored to the downstream substructure to further stabilize the bridge. 

Rehabilitation Drawings
The reconstruction of the bridge began March, 2011. 
During the summer of 2011 materials were replaced on the site and the bridge was reconstructed.  The restored bridge is scheduled for completion in November 2011.   
Dedication and re-opening of the bridge occured December 3, 2011. 

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What is a Howe Truss Bridge?  (The pictures above show the Howe Trusses exposed)
How(e) It Works, By Steve Hauff
(Reprinted with permission from The Trainmaster, November 2009)
From its invention and patenting in 1840 , until the style finally succumbed to more modern designs and materials in the mid-1920s, William Howe's truss was a mainstay for bridge builders and architects throughout the world.  Howe originally devised the truss for architectural purposes (he needed a long span for roof in a church) but the modular aspect of the design lent itself to both road and railway bridge applications.
Howe Truss
On railways, the Howe truss fell into three general types: the pony truss, where the trusses were not as tall as the trains and there was no cross-bracing at the top of the tursses; the deck truss, where the rails and ties were carried completely above the trusses; and the through truss, where the trains went between the trusses and under a series of cross-braces at the top of the trusses.  There were covered variants of all three types, though in the case of the pony and deck trusses, the cover generally only enclosed the truss structure and not the cross-bracing.  In the case of the through truss, most were open, but there are examples of partially-covered (trusses only) and fully covered varieites, such as the Chambers Bridge. 

The design appealed to railroads for several reasons: first, the chords were essentially modular, with heavier loads being accomodated by adding members (three to seven was common) and clear spans as long as 150 feet typically used components no longer than 85 feet;  second, the angle castings and tension rods could be standardized, limiting the inventory of replacement parts; third, the compression members were square-cut and of uniform length, allowing prefabrication and pre-treatment with preservative; fourth, the relatively modest size of the components allowed the construction of the bridge without large cranes or elaborate launching structures (although falsework was required).

The genius of Howe's design was that he used materials where they worked best  - steel or iron for the vertical tension members; wood for the angled compression members; and a modular scheme for the chords.  These features, coupled with simple wood joinery, made for an easily erected and simply maintained structure.

While construction of the railroad Howe trusses essentially ended in the 1920s, a significant number of this type of bridge remained in service until 1970s and 1980s.  Unfortunately, few examples survived into the twenty-first century. 

(The Trainmaster is the Official Publication of the Pacific Northwest Chapter National Railway Historical Society, Portland Oregon.  For more information visit

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