Navajo Bridge

Navajo Bridge
View to east with 1929 bridge at left, 1995 bridge at right A portion of the Echo Cliffs is in the background.
Official name	Navajo Steel Arch Highway Bridge
Carries	US 89A
Crosses	Colorado River at Marble Canyon
Design	spandrel arch bridge with 90 feet (27 m) rise (both)
Material	steel
Total length	834 feet (254 m) 1st 909 feet (277 m) 2nd
Width	18 feet (5.5 m) 1st 44 feet (13 m) 2nd
Longest span	616 feet (188 m) 1st[1] 726 feet (221 m) 2nd
Number of spans	1
Piers in water	0
Clearance below	464 feet (141.4 m) 1st 470 feet (143.3 m) 2nd
Construction begin	1994 (2nd)[2]
Construction end	1929 (1st) 1997 (2nd)[2]
Opened	1929-06-15 (1st) 1994-10-14 (2nd)
Navajo Steel Arch Highway Bridge
U.S. National Register of Historic Places
Nearest city:	Page, Arizona
Coordinates:	36°49′2″N 111°37′53″W / 36.81722°N 111.63139°W / 36.81722; -111.63139Coordinates: 36°49′2″N 111°37′53″W / 36.81722°N 111.63139°W / 36.81722; -111.63139
Built:	1927
Architect:	Arizona Highway Dept.; Et al.
Architectural style:	Other
Governing body:	State
MPS:	Vehicular Bridges in Arizona MPS (AD)
NRHP Reference#:	81000134[3]
Added to NRHP:	August 13, 1981

Navajo Bridge crosses the Colorado River's Marble Canyon near Lee's Ferry in the US state of Arizona. Apart from the Glen Canyon Bridge a few miles upstream at Page, Arizona, it is the only roadway crossing of the river and the Grand Canyon for nearly 600 miles (970 km). Spanning Marble Canyon, the bridge carries northbound travelers to southern Utah and to the Arizona Strip, the otherwise inaccessible portion of Arizona north of the Colorado River, which includes the North Rim of Grand Canyon National Park.

Prior to the construction of the first Navajo Bridge, the only river crossing from Arizona to Utah was at nearby Lee's Ferry, where the canyon walls are low and getting vehicles onto the water is relatively convenient. The ferry offered only unreliable service, however, as adverse weather and flooding regularly prevented its operation.

History

Aerial view of the Navajo bridge. Newer bridge in the foreground and Vermilion Cliffs in the background

Construction of the original Navajo Bridge began in 1927, and the bridge opened to traffic in 1929. It 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 design was constructed by the Kansas City Structural Steel Company. The bridge is 834 feet (254 m) in length, with a maximum height of 467 feet (142 m) from the canyon floor. Its 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 necessitate the wider road.

In 1990, however, it was 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 bridge's approach had become a safety hazard due to low visibility, and the deficiency in the original design's width and load capacity specifications were becoming problematic. The bridge had also become part of U.S. Route 89A.

A view of the Marble Canyon and the Colorado River from Navajo Bridge.

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 pollution entering the river. The original proposal called for merely widening and fortifying the bridge, but this was ultimately rejected since this could not possibly bring it up to current federal highway standards. Replacement was then the only option, and it was eventually decided to entirely discontinue automobile use of 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 September 1995, at a cost of approximately $15 million.

The original Navajo Bridge is still open to pedestrian and equestrian use, and an interpretive center has been constructed nearby to showcase the historical nature of the bridge and early crossing of the Colorado River. Bungee jumpers are frequently seen using the span. The original bridge has been designated as a Historic Civil Engineering Landmark.

Bridge statistics

^{[4] [5]}

Original bridge

Dedicated: 1929-06-14 to 1929-06-15 after two years of construction
Total length: 834 ft (254 m)
Steel arch length: 616 ft (188 m)
Arch rise: 90 ft (27.4 m)
Height above river: 467 ft (142 m)
Width of the roadway: 18 ft (5.5 m)
Amount of steel: 2.4 million lb (1,089,000 kg)

Amount of concrete: 500 yd³ (385 m³)
Amount of steel reinforcement: 82000 lb (37,000 kg)

Construction cost: $390,000

New bridge

The main pin of the new bridge was set 1994-10-14, after seven months of construction.
Total length: 909 ft (277 m)
Steel arch length: 726 ft (221 m)
Arch rise 90 ft (27.4 m)
Height above river: 470 ft (143 m)
Width of the roadway: 44 ft (13.4 m)
Amount of steel: 3.9 million lb (1,769,000 kg)

Amount of concrete: 1,790 yd³ (1370 m³)
Amount of steel reinforcement: 434,000 lb (197,000 kg)

Construction cost $14,700,000

Notes

1. ^ Jackson, Donald C. (1988). Great American Bridges and Dams. Wiley. pp. 245–246. ISBN 0-471-14385-5. 
2. ^ ^{a b} See external Structurae links, below
3. ^ "National Register Information System". National Register of Historic Places. National Park Service. 2007-01-23. http://nrhp.focus.nps.gov/natreg/docs/All_Data.html. 
4. ^ Placards at the interpretive center.
5. ^ Navajo Bridge at www.nps.gov

External links

Media related to Navajo Bridge at Wikimedia Commons

• Excellence in Highway Design: Navajo Bridge
• The Navajo Bridge Project
• American Society of Civil Engineering – Navajo Bridge
• Navajo Arch Bridge (1929) at Structurae
• Navajo Bridge (1997) at Structurae