Keystone Wye is an interchange of U.S. Route 16 (US 16) and US 16A located in the

Black Hills The Black Hills ( lkt, Ȟe Sápa; chy, Moʼȯhta-voʼhonáaeva; hid, awaxaawi shiibisha) is an isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, United States. Black ...

South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large porti ...

, featuring two unique structural

glued laminated timber Glued laminated timber, commonly referred to as glulam, is a type of structural engineered wood product constituted by layers of dimensioned lumber, dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that ...

bridges. The Keystone Wye is a three-level Directional T interchange for the two divided highways, constructed in 1967-1968 as part of a project by the

South Dakota Department of Transportation The South Dakota Department of Transportation (SDDOT) is a Government of South Dakota, state government organization in charge of maintaining public roadways of the U.S. state of South Dakota. South Dakota has 82,447 miles of highways, roads and ...

(SDDOT) to convert US 16 to a four-lane highway between

Rapid City Rapid City ( lkt, link=no, Mni Lúzahaŋ Otȟúŋwahe; "Swift Water City") is the second most populous city in South Dakota and the county seat of Pennington County. Named after Rapid Creek, where the settlement developed, it is in western So ...

and Keystone. It was designed by Clyde Jundt and Kenneth C. Wilson. The high bridge (see photo in external reference) is supported by three wooden, single-hinged

arches An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it. Arches may be synonymous with vault ...

; six separate glued laminated

timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, w ...

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 the Sitting Bull Crystal Cavern Dance Pavilion in the mid-1990s. The name ''Keystone Wye'' significantly predates the construction of the modern interchange, and dates back to the 1930s and the construction of Mount Rushmore, when Senator and Governor

Peter Norbeck Peter Norbeck (August 27, 1870December 20, 1936) was an American politician from South Dakota. After serving two terms as the ninth Governor of South Dakota, Norbeck was elected to three consecutive terms as a United States Senator. Norbeck was ...

laid out a series of roadways in the south-central Black Hills for tourist travel, focusing on

Mount Rushmore Mount Rushmore National Memorial is a national memorial centered on a colossal sculpture carved into the granite face of Mount Rushmore (Lakota: ''Tȟuŋkášila Šákpe'', or Six Grandfathers) in the Black Hills near Keystone, South Dakot ...

and Harney Peak (now

Black Elk Peak Black Elk Peak is the highest natural point in the U.S. state of South Dakota and the Midwestern United States. It lies in the Black Elk Wilderness area, in southern Pennington County, in the Black Hills National Forest. The peak lies west-sout ...

). The Keystone Wye includes a

lay-by A rest area is a public facility located next to a large thoroughfare such as a motorway, expressway, or highway, at which drivers and passengers can rest, eat, or refuel without exiting onto secondary roads. Other names include motorway serv ...

with historic and scenic information about the area, a SDDOT maintenance yard, and several minor roads connecting to the major highways. In the late 1980s, US 16A between the Keystone Wye and Keystone itself was widened to a four-lane

undivided highway A single carriageway (British English) or Undivided highway (American English) is a road with one, two or more lanes arranged within a one carriageway with no central reservation to separate opposing flows of traffic. A single-track road has a ...

, with the single

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

on the road expanded to accommodate the wider roadway. In the early 2000s, US 16 between the Keystone Wye and Three Forks was improved to a "

Super-Two A super two, super two-lane highway or wide two-lane is a two-lane surface road built to highway standards with wide lanes and other safety features normally present on a freeway with more lanes, typically including partial control of access, o ...

" configuration with passing lanes on most hills, although the alignment was unchanged from the 1980s realignment project which created many cutoff loops on the highway.

References

External links

PicturePhoto on Flickr
Black Hills Open-spandrel deck arch bridges in the United States Wooden bridges in the United States Road bridges in South Dakota U.S. Route 16 Bridges of the United States Numbered Highway System Road interchanges in the United States 1968 establishments in South Dakota {{SouthDakota-road-stub