This is the Keystone Wye bridge on Highway 16 taking you to the town of Keystone and Mt. Rushmore from Rapid City, South Dakota. It was built in 1967. The Federal Govt. sponsored a highway beautification contest in the late 1960's. Each of the 50 states could submit one highway for consideration. Highway 16 was South Dakota's entry. The Highway and bridge were designed in the State capital. The plans were sent to the regional Highway Department in Rapid City. Charles Williamson was appointed chief surveyor for the project.
The Keystone Wye is a trumpet-style three-way interchange for the two divided highways, constructed in 1966-67 as part of the project converting US 16 to a four-lane, divided highway from Rapid City, South Dakota to Keystone for visitors to Mount Rushmore National Memorial.
The high bridge is supported by three 20-meter wooden, single-hinged arches; six separate glulam pieces are used in the construction. Three more pieces were built but failed quality assurance tests; they were assembled into an interesting pyramidal sculpture which for years was located just off US 16 on the then-south edge of Rapid City (a site today occupied by a motel and convenience store), and which was moved to a new location on US 16 near Sitting Bull Crystal Cave in the mid-1990s.
Washington State and trucked to the Black Hills.
Charles Williamson surveyed the expansion work for Highway 16. He surveyed all the roads leading into the interchange. He did the survey work and supervised the placement of the concrete pads anchoring the wooden arches. If his work wasn't spot, on correct the arches wouldn't have fit.
The project took two years to complete from beginning to end.
The interchange was designed before computers and calculators. Charles used a slide rule for some of his calculations but not the bridge. Slide rules were not accurate enough for five or six decimal places. Instead he used trig tables, pencil and paper.
Charles remembers that the blasting of the hillside, in preparation for the bridge's foundations and the widening of the road, brought up chunks of quartz rock with small embedded veins of gold. The Holy Terror Mine Gold Mine was down the hill from the bridge in the town of Keystone. The gold in the quartz was all part of the larger vein of gold that supported the mine.
Ray Sanders, an old nut from Rapid City, originally owned the land where the bridge sits today. He refused to sell the land to the State of South Dakota. The State had no choice but to take the land from him when he refused to accept their best offer. He was angry, and on the first day of construction, just as the bulldozers started to clear the land, he climbed a nearby hill and shot at the construction equipment below. Charles remembers hearing the pinging of the bullets as they bounced off the tractor's blades. The sheriff was called, came out, and took him to jail.