Covered Bridges in Oregon Design and Construction
Goodpasture Covered Bridge
Lowell Covered Bridge
Unity Covered Bridge
Pengra Covered Bridge
Maintenance and Preservation Concerns
When someone says "covered bridge," most people think of a small town or village in New England. In actuality, though, Oregon has many covered bridges, too. "Oregon has the largest collection of covered bridges west of the Mississippi River and the sixth-largest in the nation" (Oregonian Sept. 1 1997). Covered bridges nearly 100 years old were originally built to protect the decking of the bridge. All of the decks of bridges in the early 1900s were made of wood. Because of the large amounts of rainfall and the rate at which wood rots the bridges had to be protected by roofs. Wood products were highly available which made it possible to build roofs over these bridges fairly easily and cheaply. This is also one of the first places that new types of trusses were designed. The Howe Truss became one of the more popular ones because of the sturdiness of it and the ease of building a larger one.
Over the years these bridges have been on the decrease. "In the 1920s, Oregon boasted more than 400 covered bridges" (Oregonian Sept. 1 1997). Now Oregon only has 49 covered bridges remaining. The largest numbers of these are located in Lane County, totaling 19 in all. State Legislators have passed bills that give money to help restore this now dwindling heritage. Covered bridges have had a large impact on the culture in Lane County and need to be preserved.
Design and Construction
To provide access to more land, the government mainly built covered bridges. Other people only built a few of the bridges. The main reason that these other bridges were built was for log trucks. Many of the loggers already used bridges built by the government. Although, sometimes the government was not going to build a bridge by a particular location so the logging company had to build its own bridge.
Bridges were built using trusses. These trusses were placed down the side of the bridge and had to carry the weight that would be put on the bridge. Three different types of trusses were used. These trusses are: Kingpost, Queenpost and the Howe truss. The Kingpost has a simplistic and easy design, but it cannot be built very large because it requires single pieces of wood for the beams. If the bridge is too large, then finding a beam long enough to span the distance is hard to find. This is mostly because trees are not tall enough to get a beam of that size.
The Queenpost truss solved the problem for the lack of distance that the Kingpost truss could span. By adding another vertical beam the truss could be made much longer than the Kingpost. This type of truss still had its share of problems. Once the truss reached a certain length the beams would not be long enough. This truss ran into the same problem that the Kingpost had.
With the invention of the Howe Truss the problem of finding long enough beams was solved. "In 1840 Massachusetts builder William Howe introduced iron into wooden truss design by substituting adjustable iron rods for the vertical members of Long's truss" (Truss Types). No longer were long beams needed because all that needed to be done to make the truss larger was to add more diagonal beams. This new truss made it possible to make longer and larger bridges. The Howe Truss also made it one of the sturdiest trusses that could be built. The Howe Truss also utilized one of the greatest advantages of all over the other truss designs. This was the use of steel vertical supports. This design uses the strength of wood and steel to make a really sturdy truss.
Many other truss types exist, but out of all of them the Howe Truss, is the most widely used. The Howe Truss set in motion the design of the many of the modern trusses. Most of the new trusses are variations of the Howe Truss. "At the turn of the century, the steel and iron industry began to boom in the United States and it greatly influenced bridge design" (History of Covered Bridges). With the new materials available now such as steel, it made it much more cost effective and longer lasting than traditional wood beams. "Combined with heavier rail and truck shipments and higher levels of traffic, wooden bridges became obsolete" (History of Covered Bridges). Builders of these new bridges depended more and more on modern metals to construct their new bridges.
Goodpasture Covered Bridge
"One of the most beautiful and photographed covered bridges in Oregon, the Goodpasture Bridge is a popular representative of Oregon's covered bridge heritage" (Historic Highway Bridges, 193). Even though it is only the second longest and perhaps even the cheapest one to build, it is the most well known. Located on the McKenzie Highway, also known as Highway 126, it is set in a perfect position to see for anyone who passes by. It could not have been placed in a more beautiful spot among the evergreens and over the McKenzie River.
Built in 1938 the Goodpasture Covered Bridge only cost $13,154 dollars to build. A.C. Striker was the local county bridge superintendent at the time of its construction. It was originally constructed to allow logging trucks and families to gain access to the land on the other side of the McKenzie River. Built 165 feet long, with 10 gothic style windows on each side and false end beams, the Goodpasture Bridge was built on the Howe Truss. It was built on this truss because of the large distance it had to span. This large span makes it the second longest covered bridge in the state.
Lowell Covered Bridge
The Original Lowell Bridge was built in 1907 without a roof. The length is 165 feet spanning over the middle fork Willamette River. The bridge replaced an earlier ferry. In World War II a truck ruined the bridge, and it was rebuilt in 1945. It got its first roof in 1947. After completing the Dexter Dam in 1953, high water was expected .The bridge and connecting highway were both raised six feet. In 1981 the bridge was bypassed because of the increasing traffic. A concrete span was built to bypass the bridge.
Unity Covered Bridge
The Unity Covered Bridge has a length of 90 feet. Two bridges were close together, side by side, for many tears. "The original was 129 feet long, but was closed to vehicles in1935 "(Webber 100). The bridge stayed open for walkers until it deteriorated to the point of dismantle in 1953. A new bridge was built three quarters of a mile upstream. It took the traffic from the old bridge when it opened in 1936.
The Unity Bridge is unique. It has a long window on its east side so drivers can watch for oncoming traffic. The window has its own roof. The roof shields sun from driver's eyes and keeps the rain out. The Bridge is still in excellent condition and handles traffic daily.
Pengra Covered Bridge
The Pengra Bridge is also known as the Fall Creek Covered Bridge, measuring 120 feet long and spanning Fall Creek. The present bridge replaced the original bridge that stood nearby since 1904. "The lower chords of the bridge are the largest single piece timbers cut in Oregon, measuring 16 by 18 by 126 feet" (Webber 90). Deterioration caused the covered bridge to close down and become bypassed in 1979. There are plans to restore the bridge and reopen it to traffic. No date for the restoration has been announced.
What are the maintenance and preservation concerns?
In 1989, "the Oregon Legislature cobbled together a program to build a protective roof over the 49 remaining covered bridges in the state" (Oregonian Sept. 1 1997). Government regulations and laws that provide money for preservation of covered bridges have helped, but it is not enough. Getting government funding to pay for the preservation of a covered bridge is very difficult to obtain. Many of the small communities that have the covered bridges in them do not have the money to renovate these great structures. It is very costly to make the repairs on a covered bridge. An example of the high cost of renovation is the Goodpasture Covered Bridge, which cost $13,154 to build originally, but cost nearly $750,000 in repairs to return it to a usable condition.
During the 1993-95 biennium this government program only gave out $377,111 for the work done on 29 bridges. That is not even enough money to pay for the complete restoration of just the Goodpasture Bridge alone. Lane County though, is one of the biggest participants in this program. In August of 1997, Lane County filed for reimbursement of $171,340. Even with the preservation that is going on, many of the bridges are still in poor or very poor condition. The owners of some of these bridges cannot afford the cost of renovation so they are either tearing them down or just letting them get worse.
All of these bridges are an important part of the history of Lane County and of Oregon. Why do people just sit around and think that someone else should take the initiative to save them? If these bridges are that important to them and if these bridges are to be preserved, then people need to take a stand when the government wants to knock them down to put in a new piece of asphalt or cement. By preserving these bridges it will also preserve the history and heritage that goes along with them.
Links to other sites:
Oregon's Covered Bridges
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Dykman, Pieter, James Norman, Dwight Smith. Historic Highway Bridges of Oregon. Portland: Oregon Historical Society, 1989.
Essentix, Inc. McKenzie River Valley. [Online] Available http://www.el.com/to/mckenzierivervalley/. January 1995.
History of Covered Bridges. [Online] Available http://www.dot.state.oh.us/coverb/history_of_ohio.html. March 16, 1999
Gorski, Eric. "Many of state's aging covered bridges in jeopardy." The Oregonian, September 1, 1997.
Norman, James. Environmental Services Historic Bridges. [Online] Available http://www.odot.state.or.us/eshtm/br.html. January 1997.
Oregon's Covered Bridges. [Online] Available http://www.viser.net/~draft/bridges/bridges.shtml. April 12, 2000.
Truss Types. [Online] Available http://www.dot.state.oh.us/coverb/truss_types.html. March 16, 1999
Web Page Designed and Created by David Marchant & Lindsey Lane
Graphics provided by Oregon's Covered Bridges and Lindsey Lane
Covered Bridges in Oregon
Thurston High School
May 19, 2000
Project in its entirety available at:
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