Each year on the weekend closest to October 28, the anniversary of the completion of the Gateway Arch structure, JNPA sponsors a special event honoring the workers who actually sweated and toiled to create this international icon.
Groundbreaking for the project took place on June 23, 1959. Nothing like this structure had ever been built or attempted before. An underground visitor center, river overlooks, railroad tunnels and floodwalls were constructed first. Bids for the construction of the Gateway Arch were opened in January 1962, and the MacDonald Construction Company of St. Louis was chosen as the primary contractor, with a low bid of $11,444,418. A unique transportation system for the interior of the Arch was funded by Bi-State Development Agency by issuing revenue bonds.
The Arch was constructed between June 1962 and October 1965, primarily by the subcontractor Pittsburgh-DesMoines Steel. The first stainless steel section was placed on February 12, 1963, and the last keystone section on October 28, 1965. Between those dates several major engineering challenges were solved.
The first involved the post-tensioning bars, which were the solution to one of the major engineering problems in constructing the Arch. How do you build a 630 foot arch and keep the sides from falling inward before you place the keystone? Some engineers suggested long guy wires stretching huge distances to the north and south of each leg, but the final solution was the use of post-tensioning bars set in the concrete. These bars acted like the tendons in an arm or a leg, resisting gravity and holding back the curving legs.
When the Arch reached 530 feet an additional stabilizing strut was placed between the legs. Weight, especially the weight on each leg during construction, was always a concern to the engineers, and everything from the weight of the creeper cranes to the number of personnel and tools on each leg was carefully considered. Other questions arose, prompted by several outside firms and agencies, regarding the unique nature of the engineering. Many engineers said that the Arch was improperly designed and would not stand when completed. The project was so unique that some had to wait until the structure was completed and saw it standing on its own to be convinced.
The big day, Thursday, October 28, 1965, finally arrived. On this day the final of the 142 sections of the Gateway Arch was set in place. Squeezed into place might be a more apt description. The two gigantic 630-foot tall legs which the final section would join and make into an Arch were leaning toward one another with tremendous weight and force, held back only by post-tensioning bars and the stabilizing strut; they stood just two feet apart. Into this gap an eight-foot wide section, measuring 17 feet on each of the three exposed sides and weighing 10 tons, would have to be inserted. Huge jacks would be used to exert 500 tons of pressure to open the gap to 8 ½ feet.
Although a ceremony had been scheduled for 10 a.m., engineers and workers were worried. They knew that the heat of the sun shining on the south leg would begin a subtle expansion of the metal, elongating it by as much as 11 inches in a short period and skewing it so that wedding north leg to south leg would be impossible until the metal cooled once more. In fact, the engineers advocated "closing" the Arch at night, an idea that was quickly quashed by politicians and civic boosters. The engineers and workers conceded a daytime ceremony, but proceeded at 9:25 a.m. instead of 10 a.m. to hoist the last section.
The lift took thirteen minutes. To counteract the south leg’s expansion from the sun’s heat, the St. Louis Fire Department used 700 feet of hose to spray cold water 550 feet up the south leg, continuing from 9:30 a.m. until the end of the operation. As the final section rose into the air the crowds cheered, steam whistles on riverboats were blown, and the city rejoiced. Some school children watched the event on television, while other classes and scout groups were on site. Work in neighboring buildings came to a halt as all eyes turned toward the Arch. After the last piece was jockeyed into position at 11:04 a.m. the delicate job was almost over.
In the afternoon, at 2 p.m., workers released the twelve-ton bottle jacks and the full weight of the two legs secured the final section. The stainless steel did not buckle. Welding remained the final chore, and took up two days of work. Superintendent Brown exclaimed to his co-workers, "No other comparable event is likely to occur in our lifetime."
It is this event, so important to the City of St. Louis and in engineering history, that we commemorate each year at the end of October by honoring the people who made it all possible – the workers.
