In This State: A preservation effort for Vermont’s truss bridges

In This State is a syndicated weekly column about Vermont’s innovators, people, ideas and places. Details are at maplecornermedia.com. This week’s story is by Nancy Price Graff.

 

For two years after the Flood of 1927, Richmond's Checkered House wooden bridge sat side by side with the steel bridge being erected to take its place. (Source of photo unknown)

For two years after the Flood of 1927, Richmond’s Checkered House wooden bridge sat side by side with the steel bridge being erected to take its place. Photo courtesy of Richmond Historical Society

 

Two hundred years ago the drowning of an elderly woman trying to ford the Winooski River approximately one mile west of the village of Richmond helped rally the residents to erect a covered bridge connecting the intervales on each side of the waterway. For Richmond, which was located midway on the busy stage road connecting Montpelier and Burlington, that drowning was a tragedy but also an excuse to abandon an unreliable ferry system.

The finished double-lane bridge was impressive.

“It was a Burr arch truss bridge,” says Robert McCullough, an assistant professor of historic preservation at the University of Vermont and author of “Crossings: A History of Vermont Bridges.” Like many of the patented trusses, each of which is a unique arrangement of triangular framing, the Burr truss took its name from its inventor. McCullough can tell at a glance what kind of truss system distinguishes each of Vermont’s historic bridges.

Robert McCullough, a founder of the Vermont Historic Bridge Program, which has developed plans for preservation of every truss bridge in the state. Photo by Nancy Price Graff

Robert McCullough, a founder of the Vermont Historic Bridge Program, which has developed plans for preservation of every truss bridge in the state. Photo by Nancy Price Graff

“A Burr arch truss was a good choice for such a long bridge,” he notes, looking at a photograph of Richmond’s long-gone covered bridge over the Winooski. “The arch and the multiple king-post trusses combined two structural systems to increase support and rigidity.”

The bridge acquired the name the Checkered House Bridge as a nod to a nearby 18th-century brick house, which boasts a distinctive pattern of burned bricks on one end. Even today the house is easily visible from the interstate.

Who knows how long the bridge might have served if not for the Flood of 1927. That flood devastated the Winooski Valley, taking out every bridge between Montpelier and Burlington, except the Checkered House Bridge. Battered and bruised by the raging waters of the Winooski River, the bridge somehow held its own. However, the flooding compromised abutments on both ends of the bridge. Ultimately, what nature failed to do, man was forced to do.

The Flood of 1927 washed out roughly 1,200 bridges. Faced with an intolerable disruption of its motorways, Vermont launched an emergency bridge-building program and dedicated millions of dollars to replacing bridges as quickly as possible. Wherever practical, steel bridges replaced wooden bridges. To restore travel between Montpelier and Burlington, a steel bridge soon began to rise alongside Richmond’s undermined Checkered House Bridge.

The designers of the steel bridges that were built in the five years after the flood relied on a century of truss experimentation. Bridges could be longer, higher, and wider than ever before. Scores of truss configurations had been patented. Engineers needed only to look through catalogs of designs to choose the one they needed for the circumstances.

“The Richmond bridge is the culmination of this evolving technology,” says McCullough. “By 1929 railroad engineers had modified two of the most common truss designs — the Pratt and the Parker — to produce what today’s bridge historians describe as a Pennsylvania truss.” The name acknowledges the contributions of engineers from the Pennsylvania Railroad. Pennsylvania truss bridges today are an endangered breed. Only two survive in Vermont, one crossing the Connecticut River at Brattleboro and the one in Richmond.

Steel was a gift after the flood. Unlike a spruce tree that needed 125 years to grow sufficiently to produce a truss 10 inches by 10 inches by 40 feet, steel was an easy substitute in construction.

“Single steel I-beams could be rolled in increasingly large dimensions and shaped to achieve the utmost structural efficiency,” says McCullough.

The 356-foot steel bridge in Richmond was finished in 1929 for $81,000, and the 100-year-old covered bridge came down afterward. But if the truss design of the Checkered House Bridge represented a pinnacle of sorts in bridge design, it also marked an ending.

According to McCullough, bridge engineers working throughout the 1800s and the first quarter of the 1900s were not particularly concerned with aesthetics. They appreciated the elegance inherent in efficient design, but their goal was to build the best bridge possible at the least expense. Not everyone thought the bridges were attractive.

When the Lake Champlain Bridge opened in August 1929 it broadcast the greater possibilities of steel bridge construction and demonstrated a growing concern with the aesthetics of engineered structures. It also helped launch Americans' obsession with the automobile. Photo courtesy of the Vermont Historical Society

When the Lake Champlain Bridge opened in August 1929 it broadcast the greater possibilities of steel bridge construction and demonstrated a growing concern with the aesthetics of engineered structures. It also helped launch Americans’ obsession with the automobile. Photo courtesy of the Vermont Historical Society

That attitude began to change in the 1920s just as the Richmond bridge was finished. Bold highway projects across the country heralded the true beginning of the automobile age. Vermont launched the magazine “Vermont Highways” in 1930 to tout its own road improvements, to attract tourists, and to advertise how well the state was suited to business. One of the state’s supreme achievements was the opening, almost simultaneously with the opening of the Checkered House Bridge, of the stunning 2,900-foot long Lake Champlain Bridge at Crown Point.

If the Richmond bridge was purely functional old-school design, the “Lake Champlain Bridge opened a new era for bridges designed for automobiles in scenic areas through continuous design and curving forms,” says McCullough. Continuous design allowed one long bridge to be built from end to end rather than building it out of a series of connected short bridges. This made possible bridges that had previously existed only in the imaginations of members of local Chambers of Commerce.

Innovative bridges like the Lake Champlain Bridge, the Golden Gate Bridge, the George Washington Bridge, and the Cairo Mississippi River Bridge, all completed between 1929 and 1937, were examples of gateway bridges intended not just to serve the public but to put Americans in their cars for business and pleasure. Brochures advertised the new Lake Champlain Bridge as a shortcut from New York to Vermont or vice versa but also as “The New Highway across Lake Champlain,” one that takes drivers “through the Gateway of American History to a land of scenic delight.”

The Checkered House Bridge in Richmond has been draped in curtains for months as the last of the old lead paint has been removed. Once the bridge is repainted, it should have a useful life of another half century. Photo by Nancy Price Graff

The Checkered House Bridge in Richmond has been draped in curtains for months as the last of the old lead paint has been removed. Once the bridge is repainted, it should have a useful life of another half century. Photo by Nancy Price Graff

The American Bridge Company, part of J.P. Morgan’s U.S. Steel trust, fabricated the steel for both Richmond’s Checkered House Bridge and the Lake Champlain Bridge. Within three years, the American Bridge Co. would do the same for the Empire State Building. Steel created a new universe of building possibilities.

These two Vermont bridges lasted approximately the same amount of time before they required serious attention. The Lake Champlain Bridge was judged unsafe in 2009, and a replacement bridge opened last year. In 1989 the Richmond bridge was found to be sound but too narrow for modern vehicles. Over the last three years, engineers have split the bridge longitudinally and widened it by 12.5 feet. It should reopen to traffic this fall.

The Vermont Historic Bridge Program, organized in 1998, set out to prove that restoration was less expensive than replacement. Thanks to its efforts, the state now has a restoration plan for each category of truss bridge found in Vermont.

“I give the Agency of Transportation a lot of credit,” says McCullough, the program’s director. “The typical approach in many other states would have been to tear these historic bridges down and build another.”

Nancy Price Graff of Montpelier is a freelance writer and editor.

 

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