engineering

Navajo Bridge

Navajo Bridge is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Navajo Bridge rather than just read about it. In short: Navajo Bridge is the name of twin steel spandrel arch bridges that cross the Colorado River in the Grand Canyon National Park (near Lees Ferry) in northern Coconino County, Arizona, United States. The newer of the two spans carries vehicular traffic on U.S.

Key takeaways

Navajo Bridge belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Navajo Bridge to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Navajo Bridge from memory before moving on to harder problems.

Reference excerpt

Navajo Bridge is the name of twin steel spandrel arch bridges that cross the Colorado River in the Grand Canyon National Park (near Lees Ferry) in northern Coconino County, Arizona, United States. The newer of the two spans carries vehicular traffic on U.S. Route 89A (US 89A) over Marble Canyon between Bitter Springs and Jacob Lake, allowing travel into a remote Arizona Strip region north of the Colorado River including the North Rim of Grand Canyon National Park. Prior to completion of the first Navajo Bridge, one of the only Colorado River crossings between Arizona and Utah was located about 5 miles (8.0 km) upstream from the bridge site, at the mouth of Glen Canyon where Lees Ferry service had operated since 1873. The ferry site had been chosen as the only relatively easy access to the river for both northbound and southbound travelers. By the 1920s, automobile traffic began using the ferry, though it was not considered a safe and reliable crossing due to adverse weather and flooding regularly preventing its operation. The bridge was officially named the Grand Canyon Bridge when it was dedicated on June 14–15, 1929. The state legislature changed the name to Navajo Bridge five years later in 1934. The original bridge was closed to vehicular traffic after the new span opened in 1995. The old span is still open for pedestrian and equestrian use. The dual spans of Navajo Bridge are tied at ninth place among the highest bridges in the United States with nearly identical heights of 467 feet (142.3 m) for the original span, and 470 feet (143.3 m) for the second span.

History

Construction of the original Navajo Bridge began in 1927, and the bridge opened to traffic in 1929. The bridge was paid for by the nascent Arizona State Highway Commission (now the Arizona Department of Transportation) in cooperation with the United States Department of the Interior's Bureau of Indian Affairs, as the eastern landing is on the Navajo Nation. The steel spandrel bridge was designed and constructed by the Kansas City Structural Steel Company. During construction, worker Lane McDaniels died after falling 467 feet (142 m) to the Colorado River below. Supervisors had rejected the idea of rigging safety netting, believing that it would catch on fire from falling hot rivets. The original bridge is 834 feet (254 m) in length, with a maximum height of 467 feet (142 m) from the canyon floor. The roadway offers an 18-foot (5.5 m) surface width with a load capacity of 22.5 tons (although the posted legal weight limit was 40 tons). During the design phase, a wider roadway was considered, but ultimately rejected, as it would have required a costly third arch to be added to the design, and the vehicles of the time did not require a wider road. When the Bridge officially opened on January 12, 1929, the Flagstaff paper proclaimed it "the biggest news in Southwest history." By 1984, however, Arizona Department of Transportation officials decided that the traffic flow was too great for the original bridge and that a new solution was needed. The sharp corners in the roadway on each side of the approach had become a safety hazard due to low visibility, and deficiencies resulting from the original design's width and load capacity specifications were becoming problematic. The bridge had also become part of US 89A.

Deciding on a solution was difficult, due to the many local interests. Issues included preservation of sacred Navajo land, endangered plant species in Marble Canyon, and the possibility of construction debris entering the river. The original proposal called for merely widening and fortifying the 1928 bridge, but this was ultimately rejected as not sufficient to meet contemporary federal highway standards. Replacement became the only option, and it was eventually decided to entirely discontinue vehicular traffic on the original bridge. A new bridge would be built immediately next to the original and have a considerably similar visual appearance, but would conform to modern highway codes. The new steel arch bridge was commissioned by the Arizona Department of Transportation and the Federal Highway Administration, and was completed in May 1995, at a cost of $14.7 million. A formal dedication was held on September 14, 1995. The original Navajo Bridge is still open to pedestrian and equestrian use, and an interpretive center has been constructed on the west side to showcase the historical nature of the bridge and early crossing of the Colorado River. The original bridge has been designated as a Historic Civil Engineering Landmark, and was placed on the National Register of Historic Places on August 13, 1981. California condors were reintroduced to the area in 1996 and can sometimes be seen on and around Navajo Bridge.

Bridge characteristics

Original bridge (1929)

Construction started June 30, 1927 Bridge opened to traffic January 12, 1929 Total length: 834 feet (254 m) Steel arch length: 616 feet (188 m) Arch rise: 90 feet (27 m) Height above river: 467 feet (142 m) Width of the roadway: 18 feet (5.5 m)

Amount of steel: 2,400,000 pounds (1,100,000 kg) Amount of concrete: 500 cubic yards (382 m3) Amount of steel reinforcement: 82,000 pounds (37,000 kg)

Construction cost: $390,000 (equivalent to $7.31 million in 2025)

New bridge (1995)

Total length: 909 feet (277 m) Steel arch length: 726 feet (221 m) Arch rise: 90 feet (27 m) Height above river: 470 feet (143 m) Width of the roadway: 44 feet (13 m)

Amount of steel: 3,900,000 pounds (1,800,000 kg) Amount of concrete: 1,790 cubic yards (1,370 m3) Amount of steel reinforcement: 434,000 pounds (197,000 kg)

Construction cost $14.7 million (equivalent to $31.06 million in 2025)

Illustrations

Worked examples

Example 1 — a first encounter with Navajo Bridge

Start with the simplest possible case. Write down what Navajo Bridge claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Navajo Bridge before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Navajo Bridge ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Navajo Bridge

In research: Navajo Bridge appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Navajo Bridge in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Navajo Bridge is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1929 establishments in Arizona, Bridges completed in 1927, Bridges of the United States Numbered Highway System, so understanding it makes those chapters shorter.
In everyday life: Look for Navajo Bridge outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Navajo Bridge in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Navajo Bridge means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Navajo Bridge out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Navajo Bridge in simple terms?

Why does Navajo Bridge matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Navajo Bridge?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Navajo Bridge.