A gossamer shawl of iron lace floating in midair: The “Rattling Bridge” between New Haven and Weybridge spans Vermont’s history, bridging the agricultural landscape to the automobile age. Built in 1908, this 148-foot long Double-Intersection Warren Through-Truss is made of forged low-carbon steel (colloquially called wrought iron). It assembled in the then-new method of riveting rather than pinning.

Technical details are not the reason this old bridge still stands to carry politely waving drivers one way at a time across Otter Creek. The Rattling Bridge, like all of Vermont’s remaining metal truss bridges, has personality, and local residents prefer their iron beauty to the prefab cast-concrete of modern highway replacements.

The Janice Peaslee Bridge, also known as the Maidstone-Stratford Holl, is an historic 1893 pin-connected Pratt through-truss over the Connecticut River on the Essex County, Vermont - Coos County, New Hampshire, line. Photos courtesy of Craig Hanchey, www.flickr.com/cmh2315fl

“A lot of these towns are closely attached to these old structures and want to keep them,” says Garrett Dague, transportation planner for Addison County Regional Planning Commission (ACRPC). “They call this one the Rattling Bridge because the boards rattle on the deck as you drive across it. They even designed the rehab so that new boards will replace the old ones but keep the rattle. They have a lot of character, these old bridges.”

“It’s an old bridge, it’s a beautiful bridge, and it made sense to leave it,” says Tim Bouton, a senior planner at ACRPC and a New Haven resident who has followed the Rattling Bridge preservation efforts for years.

On the other side of Addison County, another beautiful old bridge has passed the point of no return: Transportation officials closed the Champlain Bridge in autumn 2009, and then announced the bridge would be demolished.

The Champlain Bridge

Vermont and New York ushered in automobile tourism with the 1929 opening of the Champlain Bridge connecting Chimney Point, Vermont and Crown Point, New York. A continuous steel truss bridge, it had two deck-truss spans linked by a central through-truss span that allowed boats to pass while adding a visually lifting design element. Planners were starting an orderly examination of options for the bridge’s future as early as 1988.

“Originally there was a good chance it would be rehabbed, but pier problems appeared that are not fixable,” says Richard Kehne, ACRPC transportation planner. Although only four years had elapsed since the last inspection, engineers analyzing the bridge for the environmental impact staement found “massive deterioration,” Kehne says. “The caissons go 100 feet down to bedrock, they are massive below the ground under the mud, and their condition is very questionable. The pier stems are the part you see coming up from the water to the bridge. There are half-inch open cracks going all the way around the piers at some points. The bridge could fall at any moment.”

Kehne says the bridge was “a little peculiar in its design. They poured the piers without steel reinforcing, that was not typical even at that time, and they did not armor the piers at ice level. Ice exerts huge pressures,” which are obvious in the pier damage. The builders also did not use air-entrained concrete, “which helps insulate it by incorporating tiny bubbles into the concrete mix. Concrete that is not air-entrained will lose 25 percent of its strength after just a hundred freeze-thaw cycles. This bridge has seen thousands of freeze-thaw cycles,” Kehne says.

Bridges to the Past

Metal truss bridges have been built in Vermont since 1859. A state study done in 1997 found 111 still standing. The bridges include an impressive range of size and age: from a 350-foot-long Pennsylvania through-truss to a 36-foot-long Warren pony truss; from a circa-1870 C.H. Parker bowstring pony truss built following the Civil War to the precursors of modern highway overpasses.

Vermont’s oldest example, built by the Boston Bridge Company, has hollow top cords — a unique feature that designer Thomas Mosely claimed strengthened the bridge without adding weight. It is owned by Bennington Museum and presently sits in a landfill awaiting restoration. Vermont’s only in-state fabricator of metal truss bridges was Vermont Construction Company, a subsidiary of the R. F. Hawkins Iron Works. The Foundry Bridge in Tunbridge is the sole surviving example of its work.

In early days, small bridge fabrication companies worked hard to sell one bridge at a time directly to each municipality. The shift from timber to iron bridges was gradual, and depended primarily on the persuasive skills of metal bridge company’s traveling salesmen. The lengths to which competing bridge sellers would go to convince selectmen were the stuff of legend. Before the turn of the 20th century, each bridge was designed and engineered for the site and customer, producing a vast array of custom designs.

In 1900, financial giant J. P. Morgan saw America’s future in the automobile and decided bridges were a sure-bet growth industry. He founded the American Bridge Company, purchasing 24 bridge fabricators including the two premier suppliers to Vermont (Berlin Iron Bridge Company and Groton Bridge Manufacturing Company), cornering more than half the nation’s iron bridge manufacturing capacity. Applying Henry Ford’s innovative component manufacturing methods, American Bridge Company began to standardize Pratt and Warren truss designs, and replace pinned assembly techniques with rivets.

Decisions regarding bridge procurement remained a local affair until 1915, when the Vermont Legislature established its first Bridge Fund. A bigger boost for metal bridge building came in 1917 when the federal government passed funding for rural communities to improve mail delivery with better roads. Prior to that, although metal bridges were built, locally available stone and timber had remained the primary bridge building blocks.

When towns like New Haven and Weybridge joined hands to build their bridge entirely with local funding in 1908, it was still possible to specify the kind of light, lacy-looking construction that, together with its chattering deck, make the Rattling Bridge such a unique and beloved local feature. The advent of state and federal roadway funding dovetailed with Morgan’s standardization of roads and bridges; steel and concrete steadily became standard materials for bridge construction.

The 1927 flood destroyed more than 1,200 Vermont bridges. To rebuild as quickly as possible, the trend towards standardization was accelerated. Bridge components were manufactured in rolled sections — the now-familiar “I” beams and channels — rather than built-up members made of individual flat pieces and corner angles. About half of Vermont’s remaining metal truss bridges were built in the aftermath of the 1927 flood. By the late 1920s, steel-plate girders with reinforced concrete began to dominate bridge construction, and the 1940s saw the introduction of large-scale highway and interstate bridges like the continuous girder Portland Street overpass in St. Johnsbury. The age of iron lace had ended.

Spanning Challenges

Maintaining Vermont’s metal truss bridges in working order as roads presents challenges. They are narrow and ill-suited to carry ever-increasing loads such as long fire engines and heavy 53-foot cargo trucks headed to big-box stores. Federal funding can be limited or unavailable, since metal truss bridges usually do not meet highway standards for weight and road width. Transportation experts predict that iron and steel truss bridges will become more rare than the revered covered wooden bridges, whose contribution to the aesthetic and economic landscape recognized.

Since 1998, Vermont has attempted to preserve some historic metal bridges through adaptive re-use, converting them to pedestrian walkways or a bike paths. “I don’t believe there are many programs in place to actually move the bridges like we do,” says Susan Scribner, project manager of the VTrans Historic Bridge Program. “These old bridges offer us a documentation of engineering history,” Scribner explains. “Once they’re gone, they’re gone. I think they’re beautiful. They’re very delicate. They’re great engineering marvels.”

Scribner cites her favorite bridge as an example: the “Old Iron Bridge” off Route 30 in Dummerston is a Quadruple Intersection Warren Through-Truss built in 1892 by the Berlin Iron Bridge Company. Its airy iron diamonds stretch through the sky in a style reminiscent of swirling fishnet stockings — yet it managed to carry car traffic for over 100 years.

“Even ordinary bridges can contribute important elements in Vermont landscapes,” says Bob McCullough, the UVM historic preservation professor who developed the Historic Bridge Program at VTrans. “They are very strong visual elements, creating a visual progression through the landscape.”

Preservation efforts can create their own challenges. “If we start to modify the design of the bridge to accommodate greater strength, some people think we alter its historic integrity. We can bypass the old bridge, leaving it for alternative uses, but often those bridges become neglected and disappear,” McCullough says. “Is the result a preservation or something different? Is it more important to keep the bridge functioning on the roadway system, or to preserve its historic structure?”

Successful Efforts

The showpieceof the Vermont Historic Bridge program’s restoration efforts is the showy Highgate Falls Bridge near Highgate Center. Built in 1887 by the Berlin Iron Bridge Company, the structure comprises two lenticular, or lens-shaped, truss bridges running together. The first is a pony truss (open at the top) serving as an approach span to a through-truss (a bridge with a latticed ‘roof’). Both spans are pin-connected rather than riveted. Its lovely arched lines now escort pedestrians across the Missisquoi River Gorge.

Few truss bridge restorations garner as much community devotion as the Elm Street (Route 12) bridge in Woodstock, recognized nationally by historic preservationists as a precedent-setting historic rehabilitation effort. The bridge still carries vehicle traffic, due to a restoration method known as “false fascia”: the original truss components have been moved outward, and a bridge meeting modern roadway standards was built in between them.

A small pony truss bridge in Hinesburg was relocated to a nearby pedestrian path less for sentimental than for practical reasons. “We were building a sidewalk at the time from the village to the new post office, and there’s a canal that had to be crossed, so they took that bridge and put it there,” recalls Melissa Ross, Hinesburg town clerk. “It was partly economics, but the timing just happened to be right. It was kind of nice to be able to recycle and reuse something rather than send it off to the scrap heap.”

The Future Of Iron Lace

The Vermont Historic Bridge program addresses the challenges of metal truss bridge preservation by remaining open to creative options. Two bridges were transferred from storage to the University of Massachusetts, to be rehabilitated by engineering students then incorporated into the campus walkway system. Others have been moved to new towns as pedestrian bridges. For example, the former Waitsfield 22 is now a sidewalk bridge in West Rutland, on Clarendon Avenue. Twelve more bridges are in storage, awaiting re-use proposals by nonprofit organizations and public entities.

Because most of Vermont’s historic metal truss bridges are owned by towns, communities hold the keys to the future of truss bridge preservation. The Vermont Historic Bridge Program enters into preservation easement agreements with towns to save their qualifying bridges. Under these agreements, there is no local share to be paid on rehabilitation costs; however, towns must agree to continue regular maintenance of the restored bridges, and not allow them to disintegrate through neglect.

Despite the historic bridge preservation program, the Vermont Agency of Transportation seems to favor building new bridges rather than fixing old ones. “It is a much simpler process to remove the old bridge and build a new one rather than repair the old one, even if the repair is often cheaper,” says Tim Bouton.

The Rattling Bridge was repaired rather than replaced because community sentiment and the Regional Planning Commission’s persistence prompted local legislators to insist that the project rise to the top of the VTrans funding list. “Of course, compared to the Champlain Bridge, this is also easier to do with a shorter span and a configuration where you can just lift the bridge right up and set it down on the ground to work on it. They physically lifted it off its piers and sandblasted it outside the waterway,” Bouton says. “It seems more workable on a short truss bridge than on Champlain.”

Manning the Gap

The loss of the Champlain Bridge has left more than an aesthetic gap in central Lake Champlain. “The bridge being out is having a huge, huge impact on Addison County,” says Kehne. “Of the 3,500 or so average auto daily trips, 600 are job-related commuter trips into Addison County. Ten percent of the Porter Medical Center’s staff and similar numbers at Middlebury College and Goodrich in Vergennes commute over that bridge, and now there is a 90-mile detour. Many of those jobs are the lower-paying jobs, and the folks live in New York because it’s more affordable. The rest of the daily trips across the bridge include tourism, some trucking, people commuting outside Addison County or using services in the county. There’s a massive local economic impact. The Route 17 corridor businesses are seeing an 85-90 percent drop-off in business.”

Planners had already been considering these impacts for the time period that the bridge would be going through rehabilitation or restoration, but they didn’t expect it to happen this soon. Agencies on both sides of the lake are manning the gap, working diligently to get temporary 12-month-round ferries in place. “The state archaeology teams are out there right now doing their investigations in the area for the new dock they need to build for a ferry and the agencies are scrambling for the permits,” Kehne says. “There are historic sites on both sides of the lake, the forts on both sides, with historical importance going way back — French and Indian War, War of 1812 — so it’s a bit of a nightmare when it comes to permitting. Basin Harbor pulled their passenger yacht out of winter storage and is ferrying pedestrians back and forth. Addison County Regional Transit is running 60 trips a day driving people from the boat dock to their jobs.”

With the old bridge out of the way, the EIS process for a new bridge on the same alignment will be expedited. “This site is narrow, so it’s the best option,” Kehne says. “Now it’s a matter of picking the appropriate design. This bridge is really unique in the United States. It has a strong visual impact with natural environmental and historic sites at either end. So the focus will be on site-appropriate design, and it will be a very public process.”

“The bridge is irreplaceable,” Bouton says. “but, that said, I recognize that if anyone pays attention to the aesthetics they could put up a really lovely bridge here.”

Cindy Hill lives in East Middlebury.