Almost 900 feet above the Colorado River, the views from the Mike O’Callaghan-Pat Tillman Memorial Bridge are spectacular. Tourists have a panoramic view of the Hoover Dam and the blue-green waters of the river, which travel from the top of the dam to the bottom. This technological marvel is surrounded by red rock canyons, providing a stark contrast between industry and nature.
While tourists enjoy the view, construction is taking place on the bridge deck on the other side of the barrier. Bags of Armorstone from Washington Rock are lined up on the Arizona side of the bridge, and workers are busy applying the stones to the Nevada side.
Read more to learn about the Memorial Bridge and how Armorstone became a new part of its incredible legacy.
The Memorial Bridge Experience
Straddling Black Canyon, the Memorial Bridge connects Arizona and Nevada via U.S. Route 93.
A visitor parking lot lies on the Nevada side of the bridge. Stairs and a long, winding ramp climb up the hillside and lead through a series of plazas to the pedestrian pathway on the bridge.
The journey from the parking lot to the pedestrian walkway on the bridge takes some time. Informational plaques along the way detail the bridge’s history and construction challenges. Anchors secured in rock walls demonstrate the process of stabilizing the canyon for the bridge.
As tourists walk out onto the bridge, winds whip past them and threaten to shake loose unsecured hats. The pedestrian walkway stretches alongside the 1,900-foot-long bridge.
Informational plaques at points along the bridge give background about the Hoover Dam as well as the bridge. Each stop offers a different perspective of Hoover Dam and the surrounding vistas.
American Engineering on Display
Hoover Dam is considered one of the greatest engineering feats of the 20th Century. The Memorial Bridge continues the tradition of extraordinary American engineering. It earned its spot in history as the highest concrete-arch bridge in the world. It is also the highest and longest single-span concrete arch bridge in the Western Hemisphere.
The bridge was the centerpiece in the Hoover Dam Bypass project, which rerouted U.S. Route 93 away from Hoover Dam over Black Canyon.
Before the bridge was built, Route 93 crossed over the top of Hoover Dam. Up to 16,000 vehicles per day used the two-lane road on top of the dam, sometimes leading to delays up to two hours.
Other concerns about the long-term safety of the route launched the Hoover Dam Bypass project. The Memorial Bridge serves to not only reduce traffic across the Dam but to also improve air quality and offer tourists access to the best views in the canyon.
Designing the bridge took two years.
Architects began by narrowing down the style of bridge that would work best for Black Canyon’s unique challenges, such as “high winds, extreme heat, and earthquakes,” according to the U.S. Department of the Interior. The deck arch design “combines a concrete arch with a steel superstructure.” It was chosen because it made staging construction easier than other designs, and it required less maintenance than other bridge designs. The absence of cables, such as in suspension bridges like the Golden Gate Bridge, also allows unobstructed views of the skyline.
After the design was completed, electrical lines had to be relocated, and a new highway approach had to be constructed before the bridge itself could be constructed. Bridge construction then took about five years, starting with laying the footing and ending with paving the road.
At a cost of $114 million, the bridge took nearly a decade to complete. It’s now the quickest route between Phoenix and Las Vegas.
Naming and Celebrating the Bridge
Then-governors of Nevada and Arizona came together in 2004 to announce the namesakes of the bridge: Pat Tillman and Mike O’Callaghan.
Pat Tillman gave up his NFL career to enlist in the U.S. Army after 9/11. He was killed in Afghanistan in 2004 by friendly fire, an incident which was widely discussed and debated in media at the time and continues to be discussed today.
Mike O’Callaghan is considered the most popular governor in Nevada history. He was a decorated Korean War Veteran. He worked as executive editor for the Las Vegas Sun after retiring from politics and died in 2004.
After its dedication on October 14, 2010, a one-day event called Bridging America allowed the public to walk the bridge before it opened to traffic. Thousands walked the bridge and took in the incredible views. The Memorial Bridge officially opened to traffic on October 19, 2010.
Protecting the Bridge Deck with Armorstone Overlay Aggregates
Washington Rock has been shipping Armorstone overlay aggregates to Nevada for many years for use on highly visible projects, including overpasses along I-15 in downtown Las Vegas. The Memorial Bridge project is the most highly visible project Armorstone has been used on to date due to the Hoover Dam’s status as a national historic site.
“Not only will motorists drive over the Armorstone overlaid bridge, but tourists use the walkway of the bridge to get a majestic view of the Hoover Dam,” Armorstone sales rep Dale Mortensen said. “This means more people will see our rock up close than any other bridge we have overlaid in the past.”
Armorstone is a small, crushed rock product that is spread on road surfaces treated with epoxy polymer. The epoxy polymer provides a protective coating that protects the road from weatherization and chemical deterioration. The Armorstone coating adds friction back to what would otherwise be a slick surface.
As the liquid epoxy dries, it acts like a glue that binds Armorstone to the surface of the road.
The Memorial Bridge, with a length of 1,900 feet and a span of 1,060 feet, required nearly 2 million square feet of product. Contractor Las Vegas Paving used 120 bags of Armorstone on the Memorial Bridge, or about 180 tons of product. In addition to overlaying the Memorial Bridge, the company also overlaid Armorstone on five other overpasses along the Route 93 corridor.
Overlaying bridge decks requires specific conditions to ensure the epoxy polymer adheres to the surface. The bridge deck has to be thoroughly cleaned of dust and debris.
Weather is a factor too.
In the desert heat of Las Vegas, Las Vegas Paving project manager Coy Nelson often has to schedule projects early in the morning before the road surface hits 100 degrees Fahrenheit. June this year has been unusually cool, so the Memorial Bridge overlays were done between 3 AM to 11 AM.
The Memorial Bridge is 37 miles southeast of Las Vegas, just outside of Boulder City, Nevada. With no stockyard available, Coy had to ensure the right amount of supplies were available each day. There was little margin for error since delays could result in heavy fines.
In the end, the Memorial Bridge overlay project gives Coy a sense of pride.
“It’s cool that our name’s on it, and we got the opportunity to be a part of history,” Coy said.
Because of the way epoxy polymer works, Armorstone overlay aggregates must be meticulously sorted, washed, and dried. The crushing process creates stones that fit within a narrow range of sieve sizes. The washing and drying process removes as much dust as possible. Dust can prevent the rock from adhering properly.
Washington Rock’s attention to detail has made Armorstone overlay aggregates highly regarded throughout the U.S. The process of getting new products approved by state DOTs is grueling, but Armorstone is now accepted by over 40 state DOTs.
In addition to the product quality, Coy values the communication and relationships with Dale and Armorstone transportation coordinator Nikki Rogers.
“Foremost is the communication and relationships that we’ve built with Dale and Nikki and the communication between everybody,” Coy said. “It’s not easy to get material delivered thousands of miles away and have everybody be on the same page.”
Coy explained that he knows he can call Nikki about project needs and get a quick response.
“That’s what I like,” he said. “I’m more about loyalty and building a relationship. And Washington Rock seems to want to have a relationship with contractors.”
Washington Rock has shipped Armorstone as far as Hawaii and St. Thomas in the Virgin Islands.
Much of the historical information included in this blog post was obtained from signage along the Mike O’Callaghan-Pat Tillman Memorial Bridge.
For more information about Armorstone, visit our Armorstone landing page.