Boulder City in Clark County, Nevada — The American Mountains (Southwest)
Get Good Footing with Anchors & Foundations
Journeys & Heros
| | Mike O'Callaghan - Pat Tillman Memorial Bridge | |
Photographed by Sandra Hughes Tidwell, September 9, 2025
1. Get Good Footing with Anchors & Foundations Marker
Rock Anchors
To protect the foundations and stabilize the slopes, rock anchors tightly hold together the fractured rock faces on slopes and cliffs.
Geotechnical (rock and soil) engineers determined where they must stabilize the slopes by studying rock surfaces and testing rock core borings. If the fractured rock is deep, then they may install rock anchors into deeper solid rock. The rock anchor installations have a staggered pattern, like the stars on the American flag, at least five feet apart. This finished array of anchors locks the rock slope in place and helps to resist erosion.
Each rock anchor includes a steel bar tendon grouted with concrete into a narrow drill hole. To reach solid rock, the anchor hole may be more than sixty feet deep. A cylindrical metal The cap protects the bar from corroding. The rock anchors in the heavily fractured slopes in this passageway required a sheet of steel mesh fabric draped over the bar tendon extending out beyond the rock face. Thin layers of shotcrete have been sprayed to hold the rock in place under the mesh.
Concrete Foundations
Each end of the River Bridge arch bears on a huge reinforced concrete foundation cut into the rock cliff face.
To build each foundation on its rock shelf, the contractor created a cage of steel reinforcing bars enclosed in a boxlike form. The crew pumped concrete through a hose to fill up the foundation form in shallow layers or "lifts." A virtual forest of reinforcing bars projected out of the sloped face of the foundation to connect with the first segments of the twin-rid arch. The smaller foundations for the paired columns are built in a similar manner.
The arch foundations, each the size of a two-story building, transfer the thrusting forces of the bridge arch into the earth. Within each foundation, cage of steel
this page online
[Legend:]
1. Anchorage cover protects against crossion
2. Nut
3. Shotcrete prevents small, loose rock from ravelling
4. Steel mesh fabric protects areas of loose rock between anchors
5. Bearing plate and washers
6. High-strength bar tendon
7. Bar couplers splice two bar tendons end to end
8. Smooth sheathing acts as a bond breaker
9. Centralizer keeps the bar aligned in the drill hole
10. Corrugated sheathing around the bar tendon
11. Grout around the anchor
12. End cap
Topics. This historical marker is listed in this topic list: Bridges & Viaducts.
Location. 36° 0.899′ N, 114° 44.691′ W. Marker is in Boulder City, Nevada, in Clark County. It can be reached from Hoover Dam Access Road east of Boulder City Bypass / Purple Heart Highway (Interstate 11), on the right when traveling east. Touch for map. Marker is at or near this postal address: 81 Hoover Dam Access Rd, Boulder City NV 89005, United States of America. Touch for directions.
Regionally, this marker is in Nevada’s Colorado River Valley, in the Mojave Desert, and in Greater Las Vegas. It is also in the American Southwest and in the Mountain West. Globally, it is in North America, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once New Spain and also Mexicos Alta California.
Other nearby markers. At least 8 other markers are within walking distance of this marker: Find Solid Ground with Surveys & Tests (a few steps from this marker); For the Record (a few steps from this marker); Worthy of the Neighborhood (a few steps from this marker); Discover Hoover Dam (a few steps from this marker); Step by Step (a few steps from this marker); Breaking the Bottle Neck (a few steps from this marker); Design Decisions (a few steps from this marker); America's Finest (within shouting distance of this marker). Touch for a list and map of all markers in Boulder City.
Credits. This page was last revised on December 26, 2025. It was originally submitted on October 2, 2025, by Sandra Hughes Tidwell of Killen, Alabama, USA. This page has been viewed 70 times since then and 21 times this year. Photo 1. submitted on October 2, 2025, by Sandra Hughes Tidwell of Killen, Alabama, USA. • Devry Becker Jones was the editor who published this page.
