Welding Works completed a major architectural ornamentation project installed on the Great Platte River Road Archway Monument. Stretching across Interstate 80 in Kearney, Nebraska, this 309-foot-long archway honors the pioneers who traveled west, 160 years ago, on the Great Platte River Road, whose path the Interstate now follows.
Welding Works’ role in this ambitious undertaking was the fabrication of the symbolic exterior ornamentation for the structure. Designed by Kent Bloomer, the ornamentation includes two sets of 25-foot-high aluminum wings which are mounted atop the north and south towers of the Archway. Wings were chosen by Bloomer to symbolize movement, transportation and communication. An aluminum horse leaps out of one set of wings, representing the Pony Express. All aluminum plate ornaments were cleaned and left in their natural finish. Supporting the ornaments are approximately six tons of sandblasted and painted structural steel, also fabricated by Welding Works.
In addition, Welding Works completed 370 feet of 14-foot-tall aluminum pipe and plate trellis, also designed by Bloomer, and sixteen galvanized steel stanchions that support the trellis sections. The trellis stretches across the top of the Archway in a braided wave style, evoking the feeling of the Platte River. In all, approximately 12 tons of fabricated aluminum plate and pipe were used in the project. The ornaments were fabricated in pieces as large as possible to expedite final on-site assembly and attachment to the Archway, which was designed by architects Peter H. Dominick, Jr., FAIA, and Robert E. Fitzgerald of Urban Design Group, Inc., Denver, Colorado.
Welding Works negotiated the contract for the work with Kent Bloomer and originally developed the scope of the work. During the engineering and design phase of the project, the design of the wings was the first and most important step. However, each pair of wings needed an independent structure behind it and inside it for support and to allow the interfacing of the artwork to itself and the steel structure on the building. The design of these structures was the responsibility of Doug Rutledge, Project Engineer at K L & A (structural engineer for the project), who supplied rough sketches of the support structure. As complete as they were, there were countless challenges facing Welding Works as they sought to marry the artwork to the structure. Communication between Welding Works and the design engineers was ongoing, and the design engineers also made several on-site visits to Welding Works.
The welding for the project was done exclusively with the GMAW process. Welding Works certified procedures, as well as eight welders, to AWS standards for 5052-H32 and 6061-T6 aluminum material. The filler wire was 5/64″ diameter E-4043. The shielding gas was straight argon. The material varied from .090 thick sheet to 1/2″ thick plate, with the majority being .190 and 1/2″ thick. Welding Works used Miller power sources in a variety of output potentials with Miller XR-30 wire feeders. These state-of-the-art feeders allowed Welding Works to feed the 5/64″ E-4043 wire, which is very soft, over a distance of 30 feet. This was essential for the job, since the varied shapes and sizes of the artwork were so dissimilar. Some of the pieces were 12 feet by 26 feet, and at times welders were working 30 feet in the air. The vast majority of the welds were fillets in the size range of 3/16″ to 1/4″.
Cutting was accomplished by conventional band saw for the structural shapes (beams, angles, structural tubing, etc.). The plate shapes, which comprised the majority of the foliage, were cut on an AIRCO optic-eye burning machine. This machine has the capacity of cutting six feet wide by 16 feet long sections. Welding Works retrofitted the cutting machine with a Thermal Dynamics STAK-PAC with two power modules and a machine torch. This allowed the company to cut 1″ thick plate, which was the thickest section on the project. Welding Works added a C&G height sensor for automated cutting. The shapes were taken from the eighth scale and quarter scale models and blown up to full-scale flat patterns. These patterns were then made into a black-on-white template, so that the optic-eye tracer could follow the shape. An operator was thus able to cut a multitude of varied shapes with speed and accuracy. There were over 1,000 different shapes in the project.
Forming presented a considerable challenge. The models in eighth or quarter scale were the only source of information regarding how much the elements were to be formed. Bloomer’s studio scaled the models and developed rolling and forming templates for Welding Works to use. A trial and error method was generally employed in arriving at the finished look of each shape. Once the shape was developed, Welding Works used a press brake, as well as two rolling machines. The horse was the most time-consuming element of the sculpture, due to the many pieces requiring hand forming. There are over 400 pieces on the skin alone, and another 300 pieces were used to fabricate the body of the horse.
In order to ensure the artwork’s fit on the Archway, and in order to develop the struts that hold the artwork, full-scale mock-ups were required for both the north and south towers of the building. Welding Works employed two types of mock-ups. The data to place the foliage were developed from a survey of the building that was taken on the roof in Nebraska. The artwork was laid out and supported in its proper relationship to the building and to itself. Struts were then developed to hold all the foliage. To further ensure that the artwork would fit when it reached Nebraska, a complete vertical mock-up of all the assemblies was performed. The survey was used to develop pedestals that represented the building pedestals. The steel support system was erected in Welding Works’ yard, and then all the artwork was hung on the steel in full scale. Each end was also mocked-up full-scale, with all the elements placed in their proper relationship. Struts were developed for all of these pieces as well.
This simulation of the existing conditions at the site and test-assembly were especially important. Due to the complexity and the irregular shapes, Welding Works had to make sure that all assemblies fit together and would go on without any interference. Structural engineers were also able to clarify many items that were impossible to calculate on paper. The test-assembly also enabled Kent Bloomer to view the completed ornaments and determine if the artistic criteria had been met. In short, it gave all parties concerned a sense of security, knowing that any problems would be worked out at Welding Works before shipment.
After test-assembly at Welding Works, the ornamentation was delivered to Nebraska. Five truckloads, most overwidth, transported the project to the site. The Great Platte River Road Archway Monument welcomes visitors to two levels of interactive exhibits, housed within the Archway, which help make the Wells Fargo Stagecoach and the Pony Express “come alive”.