Greetings Vern,

The Society for Industrial Archeology (SIA) held its 50^th annual conference in Portland, Oregon, in June 2022, with Rebecca Burrow SIA local committee leader, along with Sandy Carter, Robert Hadlow, Susanna Kuo, and Anthony Meadow. The conference introduced SIA members to many of Oregon’s historic and contemporary industrial sites.

The word “archeology” may suggest exploring dusty ancient industrial sites, scraping for small fragments of metal and stone under a hot sun to discover an untold history. While this may be the vision for some people, for those who recognize the importance of both the historic and present United States industrial technology, SIA provides its members with rare access to historic and contemporary industrial sites. Through tours, lectures, and published articles from specialists within a field of study, preservationists benefit in their restoration work.

Vern Mesler 2022

Our journey began a week before the SIA conference on a historic bridge tour meticulously planned by Nan Jackson. The drive along Oregon Coast Highway 101 visiting Conde B. McCullough’s concrete and steel bridges was memorable for both engineering and artistry. (For more information on Conde B. McCullough’s Oregon bridges, see “Crossings: McCullough’s Coastal Bridges” by Judy Fleagle and Richard Knox Smith, Pacific Publishing 2011.)

McCullough’s riveted steel bridges were impressive, and we spent the most time at the Yaquina Bay Bridge in Newport. As you ascend from the southern approach of the Yaquina Bay Bridge and then descend after reaching the center of the bridge, there is a sensation of flight. The city of Newport’s true scale is visible only after you have driven the entire length of the bridge.

From Newport’s Clearwater restaurant, the bridge’s dimensions are clearly visible: 3,260 feet in length, with a 600-foot riveted steel central arch 245 feet above water level. We would later walk out to the center of the Yaquina Bay Bridge to photograph and measure the riveted sections and admire the Art Deco concrete features and the Gothic style arch handrails. It seemed to me that the handrail on the bridge was not much to prevent one from dropping the 133 feet to the surface of Yaquina Bay. 

Across the Willamette and Columbia Rivers, the many bridges of Portland, Oregon, hold a historic record not written in books but visible in the fabricated riveted members of their spans. During “Bridges of Portland,” an SIA tour led by Sharon Wood Wortman and Ed Wortman, co-authors of “The Portland Bridge Book,” they passionately described many of those unwritten features of Portland’s bridges. Of all the bridges we were introduced to while in the Portland Metro Area, the St. Johns Bridge was our favorite, its riveted towers and trusses and its graceful arches all impressive. Wortman’s introduction to the St. Johns Bridge was to walk the SIA participants through Cathedral Park’s Gothic arches at the bridge’s main piers and in front of the 29,000-ton reinforced concrete east anchorage. In Ed Wortman’s words, the anchorage was “treated with mouldings and relief to harmonize with the architectural design of the main piers.” Sharon Wood Wortman shared with the SIA group her personal connection with the St Johns anchorage and arranged with Shawn Oliphant, Oregon Department of Transportation Region 1 Crew Manager, for his employee Zach Perez to meet us to open the steel-barred gate and heavy steel door that led to the anchor chain buried deep in the reinforced concrete.

Our SIA tours ended with departing farewells to longtime historic bridge friends, and we packed our rental car, grabbed coffees at Oak Street Coffee (tucked under the parking ramp across the street from the historic Benson Hotel), and drove to the St. Johns Bridge to spend time among its sculptured riveted steel members.

Nathan Holth of historicbridges.org describes the bridge in words an enthusiast of fine art would use for a memorable work of art: “Arguably one of the most beautiful bridges in the country, this bridge embodies the pinnacle of bridge aesthetics. Its beauty is solely derived from creating structural bridge elements that are themselves beautiful rather than adding superficial decorations to an ugly bridge structure.”

Visible throughout the graceful St. Johns Bridge, fabricated in steel, there are patterns of shop-driven rivets spaced in uniform dimensions and large convex rivet heads formed for strength.

There are no published pictures of the St. Johns Bridge being fabricated with craftsmen operating large pneumatic riveters, driving the millions of shop rivets that are normal quantities for large suspension bridges. Only the craftsmen who drove the field rivets with pneumatic hammers are documented, while the shop craftsmen who drove the vast majority of rivets are left in silence.

Lack of Knowledge of the Shop Riveting Process

Working on the preservation of historic riveted truss bridges, I discovered a stunning lack of knowledge within the engineering community of the shop riveting process versus the field riveting process. This distinction matters. For example, rivets driven with pneumatic riveting equipment in the fabrication shop have bearing and shear values greater than rivets driven with field riveting hammers, and this would have been taken into account in the engineering design. Traveling across the United States visiting and inspecting riveted bridges and other riveted structures, I’ve come to realize it is not about restoring one historic riveted truss bridge but recognizing and maintaining the enormous number of riveted structures that are still a vital component of the working infrastructure in the United States. Educating current preservationists, engineers and skilled trades workers about both field and shop riveting is essential to this work. When the riveting process was replaced in steel fabrication, the large pneumatic riveting machinery and shop knowledge of the riveting process disappeared. Engineers with experience in designing riveted structures and the knowledge and experience with the riveting processes in decline, there was no transmission of their knowledge through education to the younger generation of engineers.

Distorted Historic Record

This lack of knowledge of rivet processes extends to the historic written record as well. If you were to do an internet search for the number of rivets in the George Washington Bridge or the Golden Gate Bridge, you would get the impression that each of the 20,550-ton towers of the George Washington Bridge and the 22,200-ton towers of the Golden Gate Bridge are held together with a few hundred thousand rivets. Over the years, the focus of the written history of the Golden Gate Bridge has been on the spectacular erection of the towers and the spinning of wires across the Golden Gate. The word “field” was soon dropped from the phrase “field driven rivets” in the historic engineering record, as if it didn’t matter. Each tower is now commonly recorded as being held together with 600,000 rivets. This number actually only represents the number of field rivets in the connections. The vast majority of the rivets in the bridges are those that were driven in the shop.

“The rivets were of carbon steel, 1 in. in diameter for the main members, although a few 7/8-in. rivets were used in the portals; a total of 488,000 field rivets were driven in the New Jersey tower and 498,000 in the New York tower” (Transactions of the American Society of Civil Engineers, Volume 97, 1933. George Washington Bridge: Construction of Superstructure, pp. 260, emphasis mine).

“There were about 600,000 field driven rivets in each tower. The rivets were heated in coal-burning forges located on scaffolds outside the tower and passed to crews within the tower by pneumatic rivet-passers through holes 6-1/2 inches in diameter and left in the tower webs for that purpose” (The Golden Gate Bridge: Report of the Chief Engineer to the Board of Directors of the Golden Gate Bridge and Highway District – California, September 1937, pp. 148-9, emphasis mine).

A Tower of Shop Driven Rivets

Shop driven rivets can be seen on the Golden Gate Bridge tower in the photograph on the left from “Spanning the Gate: Golden Gate Bridge Highway and Transportation District,” (pg. 82). Shop driven rivets are visible in nearly every square foot of these massive steel towers. They were driven with large pneumatic and hydraulic riveters operated by shop craftsmen, their history rarely recorded, their story and industrial tools rarely exhibited in museums.

Photograph inserted in upper right-hand corner: “View of column-sections at boxing skids. One column-section has been riveted and is ready for the milling operation; the other is in the reaming and drilling stage” (The Golden Gate Bridge Report of the Chief Engineer, p. 238.) Note the large shop riveter to the right of the bridge sections, similar to the hydraulic riveter in the photograph on the far right: “Hydraulic riveter with traveling gantry at Pencoyd’s bridge shop” (The Engineer, March 6, 1903, p. 23), as illustrated in Kevin Righter’s book, “Philadelphia’s Pencoyd Iron Works” (The History Press, 2020).

August 2022, ISP Chronicle

June 2022, ISP Chronicle

March 2022, ISP Chronicle

February 2022, ISP Chronicle