Arch Bridges: Dirty Devil River Bridge

At milepost 45 on State Route 95, an open spandrel, steel deck arch bridge crosses the Dirty Devil River. A couple of miles further down State Route 95, a through arch bridge crosses the Colorado River at Hite (shown on February 11th).

The bridge over the Dirty Devil River is perhaps less spectacular than the landscape that surrounds it. I wonder how difficult it is to maintain bridges in Utah? This desert used to be an ocean, and the Dirty Devil River adds 150,000 tons of salt to the Colorado River every year. Still, there isn't much rain or snow in the high desert, and bridges should age slowly.

There are also a number of stone arch bridges at Natural Bridges National Monument a couple of miles farther down State Route 95.

Arch Bridges: Dirty Devil River Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.

Arch Bridges: Navajo Bridges

In the nineteenth century, travelers in eastern Utah had a 600 mile (960 km) detour to get across the Colorado River into western Arizona.  In 1873 John Lee started a ferry service at the mouth of Glen Canyon. However, In the 1920's it was decided to build a bridge five miles downstream from Lee's Ferry, across Marble Canyon. The bridge was constructed with tie-backs supporting the two sides until they met in the middle. The area was extremely desolate and when the ferry sank killing three workers, people had to drive 800 miles to get across the river until the bridge was completed in 1929.

It's a steel, deck arch with laced spandrel columns. It has a span length of 616 ft (188 m), an arch rise of 90 ft (27.4 m), its 467 ft (142 m) above the river and has a width of 18 ft (5.5 m). However, the bridge couldn't carry heavy trucks, it made a kink on U.S. Route 89A that caused many accidents, and it was too narrow to carry two lanes of traffic.  In the 1990's it was decided to build a second crossing to address these problems, and to make the old bridge a pedestrian crossing.  The new Navajo Bridge is another steel, deck arch, but longer, wider, and able to carry heavier loads.

This photo looks west from the Navajo Nation across Marble Canyon at the old Navajo Bridge. More information about these bridges is available at:

http://www.nps.gov/glca/historyculture/navajobridge.htm

Arch Bridges: Navajo Bridges by Mark Yashinsky is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.

Arch Bridges: Glen Canyon Bridge

The Glen Canyon Bridge carries US-89 across the Colorado River at Page, Arizona. The bridge was built just downstream from the Glen Canyon Dam and was completed in 1959 (the dam wasn't completed until 1966).

Like the Alexander III bridge we studied yesterday, this structure is a deck arch, although considerably different in appearance. It has a single 1027 ft (313 m) span between the faces of the canyon's walls.

The steel members were fabricated in California, assembled to ensure that everything fit, then disassembled and shipped by rail to Flagstaff, and trucked to the job site. Meanwhile, the sides of the canyon were prepared for the foundation with light blasting and drilling. A tie-back system on towers was used to assemble the arch with rivets. Spandrel columns were preassembled, lowered into position, and attached to the arch. High-strength bolts connected the deck system to the columns and leave-in-place forms were used to cast the concrete deck. The entire bridge was constructed in a single season. The U.S. Bureau of Reclamation oversaw construction by the joint venture firm of Kiewit Judson Pacific Murphy. The bridge was constructed without any fatalities and only a few injuries. More information on this project is in the February 1959 issue of Civil Engineering Magazine.

The Glen Canyon Bridge is 700 ft (213 m) above the Colorado River, making it the fourth highest bridge in the U.S. We've previously studied the fifth highest bridge, New Mexico's Rio Grande Gorge Bridge. Both bridges were constructed to avoid obstacles caused by the earth's tectonic activity. The Rio Grande Gorge was formed due to the Pacific Plate's movement with respect to the stable North American Plate. The Colorado River created deep canyons by cutting through sedimentary layers that were slowly rising due to tectonic stresses.

As I mentioned, the bridge was part of the project to dam the Colorado River, a controversial project due to its negative impact on the environment. I like to think that bridges are environmentally benign, but often they are not. This bridge was built to provide equipment, material, and workers access to both sides of the dam during it's construction.

Arch Bridges: Glen Canyon Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution 3.0 United States License.

Arch Bridges: The Hite (Colorado River) Bridge

Although the Colorado River runs 400 miles through Utah, there are only a couple of bridges that cross it.  The Dewey Suspension Bridge was built in 1916 but was accidentally burned down in 2008.  An unnamed bridge on US Route 191 was built in 1955 and crosses the river near Moab.  The Hite Bridge on State Route 95 was built in 1966 and crosses the Colorado River near the town of Hite.  Arch bridges are a good choice for crossing deep river canyons.  The arch supports can be founded on hard rock and can span up to 300 meters. The Hite Bridge is a steel, through arch with box girder arch ribs and I-girder cross-bracing. A through arch supports the deck from below (with spandrel columns) and above (with cables or ties). The ends of the arch ribs are pinned to reduce bending in the arches and to simplify the analysis.

The stark landscape enhances the bridge's beauty. Note the change in color from Jurassic Cedar Mesa Sandstone on the desert floor to Triassic Moenkopi Formation on the buttes. 

Lake Powell was formed by the Glen Canyon Dam about 80 miles south of Hite and a marina was built at the northern tip of Lake Powell in Hite.  However, years of drought have shrunk the lake and left the marina stranded. 

Arch Bridges: The Hite (Colorado River) Bridge by Mark Yashinsky is licensed under a Creative Commons Attribution 3.0 United States License.