Ciénega Bridge is an open-spandrel arch bridge which crosses

Ciénega Creek Ciénega Creek (English: "Hundred Springs Creek" or "Marsh Creek") is an intermittent stream located in the Basin and Range region of southern Arizona, and is one of the most intact riparian corridors left in the state. It originates in the Canel ...

and the

Union Pacific Railroad The Union Pacific Railroad , legally Union Pacific Railroad Company and often called simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Paci ...

near

Vail Vail is a home rule municipality in Eagle County, Colorado, United States. The population of the town was 4,835 in 2020. Home to Vail Ski Resort, the largest ski mountain in Colorado, the town is known for its hotels, dining, and for the numero ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

. Originally constructed in 1921, the bridge was part of

U.S. Route 80 U.S. Route 80 or U.S. Highway 80 (US 80) is a major east–west United States Numbered Highway in the Southern United States, much of which was once part of the early auto trail known as the Dixie Overland Highway. As the "0" in the rou ...

, a major transcontinental highway, from 1926 to 1956. Being the oldest bridge of its kind in Arizona, the Ciénega Bridge is listed on the

National Register of Historic Places The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...

. The bridge also holds the title of being the longest open-spandrel concrete arch bridge within the state. Currently, the bridge carries Marsh Station Road, which is part of Historic U.S. Route 80 as of 2018.

History

Planning and construction

In 1920, the

Arizona Highway Department The Arizona Department of Transportation (ADOT, pronounced "A-Dot") is an Arizona state government agency charged with facilitating mobility within the state. In addition to managing the state's highway system, the agency is also involved with p ...

began construction on a section of the Borderland Highway in southeastern Arizona. The Borderland Highway was part of the larger

Dixie Overland Highway The Dixie Overland Highway was an auto trail across the southern United States. It was conceived in July 1914 by the Automobile Club of Savannah, which envisioned a practical all-year driving route from Georgia to California. It was originally d ...

Bankhead Highway The Bankhead Highway was a United States cross-country automobile highway connecting Washington, D.C., and San Diego. The Bankhead Highway's beginnings can be traced back to 1916 when the Bankhead Highway Association was organized to promote the h ...

and Old Spanish Trail

auto trail The system of auto trails was an informal network of marked routes that existed in the United States and Canada in the early part of the 20th century. Marked with colored bands on utility poles, the trails were intended to help travellers in ...

s, which were important early transcontinental highways. The Highway Department received financial aid for the project from the federal government under Federal Aid Project Number 18 as well as a Pima County bond issue and the

Cochise County Cochise County () is a county in the southeastern corner of the U.S. state of Arizona. It is named after the Native American chief Cochise. The population was 125,447 at the 2020 census. The county seat is Bisbee and the most populous city is ...

Road Fund. As part of the highway construction, the Highway Department needed to build a large bridge over a chasm known as Ciénega Canyon, a natural feature of

, near the town of

. Running parallel through the canyon with the creek was the main line of the

Southern Pacific Railroad The Southern Pacific (or Espee from the railroad initials- SP) was an American Class I railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was operated by various companies under the ...

(now part of the

). State engineers decided to design an open-spandrel concrete arch bridge to cross the canyon. The arch would measure in length and would be a combination of two tapered ribs connecting the foundation arch to the bridge deck, supplemented by multiple concrete columns, supporting the deck. Paneled bulkheads and concrete guard rails would be placed on the sides of the bridge deck. The part of the bridge spanning the railroad would be a two span section with three piers supported by a concrete girder structure. In total, the bridge would have 5 spans, with four being approach spans. The overall length of the bridge would be with a width of . The main architect of the bridge was state engineer Merrill Butler. The exact location of the bridge was chosen due to it being the most feasible area to the place the bridge as well as the high solid rocky banks providing added support. Upon finalizing the bridge design, the Highway Department awarded construction of the bridge to a Tucson based firm called English and Pierce. Construction materials would be provided by the Highway Department. The new bridge was internally referred to as "Section F" of the Borderland Highway construction project. Construction of Ciénega Bridge started in 1920. Over of rock had to be blasted to make way for the bridge foundations. The total amount of concrete poured measured while the amount of reinforcing steel used weighed over . Erecting of the false work was a risky endeavor, as the contractors had to deal with the possibility of high water levels generated by the creek. Due to a dispute with the contractor, construction of the bridge was taken over completed by the Highway Department. The Highway Department claimed English and Pierce exceeded the original contracted price necessitating state takeover. Construction of the bridge was completed in March 1921 at a total cost of $40,000 (the equivalent of $ in ). Upon completion, the Ciénega Bridge became the longest open–spandrel arch bridge within the state of Arizona, the arch measuring in length. The arch consisted of twin tapered ribs, both of which were anchored into the concrete foundations of the structure. The Ciénega Bridge continues to remain Arizona's longest open–spandrel arch bridge as of June 2022. Starting in 1926, the Borderland Highway was designated as part of

, a transcontinental highway, the western and eastern termini of which, were located in

Savannah, Georgia Savannah ( ) is the oldest city in the U.S. state of Georgia (U.S. state), Georgia and is the county seat of Chatham County, Georgia, Chatham County. Established in 1733 on the Savannah River, the city of Savannah became the Kingdom of Great Br ...

(later

Tybee Island, Georgia Tybee Island is a city and a barrier island located in Chatham County, Georgia, 18 miles (29 km) east of Savannah, United States. Though the name "Tybee Island" is used for both the island and the city, geographically they are not identical ...

) and

San Diego, California San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

, respectively.

Bypass and replacement

The Ciénega Bridge became a heavily traveled section of US 80, which by the early 1950's, had become one of the most dangerous roads in the state of Arizona. Between 1952 and 1955, 11 motorists had been killed in separate car accidents in relation to the eastern bridge approach design. The eastern approach to the bridge consisted of an eight degree downhill curve just before the foot of the concrete structure. The bridge itself crossed a chasm above the creek. Motorists were unable to negotiate the dangerous curve, which had resulted in vehicles missing the bridge, driving off the chasm ledge next to the bridge, and landing on to the creek bed below. Construction started in 1952 on a bypass route which included a new railroad underpass and two wash bridges. The new straighter alignment opened on April 9, 1955, moving US 80 designation off Ciénega Bridge onto a newer bridge downstream. The new Ciénega Bridge was only above the creek as opposed to the original bridge and had a straighter more even graded approach. Upon the opening of the new route, ownership of the old bridge was transferred to Pima County, remaining open to vehicular traffic. The section of US 80 between Tucson and Benson would later be replaced by

Interstate 10 Interstate 10 (I-10) is the southernmost cross-country highway in the American Interstate Highway System. I-10 is the fourth-longest Interstate in the United States at , following I-90, I-80, and I-40. This freeway is part of the originally pl ...

, with the US 80 designation being retired from this section of highway in 1977. The US 80 designation was fully decommissioned within Arizona by 1989. The Ciénega Bridge was added to the

on September 30, 1988. The majority of the original bridge structure remains unaltered, the exception being the original guardrails, which had been replaced by Jersey barriers in 1989. Although the guardrail replacement has slightly weakened the bridge's overall structural integrity, it does not pose a significant threat. The Ciénega Bridge is the oldest surviving open-spandrel arch bridge in Arizona. As of September 21, 2018, the bridge carries a section of Historic U.S. Route 80, as the

Arizona Department of Transportation The Arizona Department of Transportation (ADOT, pronounced "A-Dot") is an Arizona state government agency charged with facilitating mobility within the state. In addition to managing the state's state highways, highway system, the agency is also i ...

(ADOT) designated Marsh Station Road as part of the historic route.

Gallery

File:Cienega Bridge Concrete Marker Arizona 2014.jpg, alt=Concrete marker for Ciénega Bridge showing dates of construction., Concrete marker for Ciénega Bridge showing dates of construction. File:Cienega Creek Natural Preserve Bridge Marker Arizona 2014.jpg, alt=National Register of Historic Places plaque for Ciénega Bridge.,

plaque for Ciénega Bridge. File:Cienega Bridge.jpg, alt=Photograph focusing on the supporting arch of Ciénega Bridge., Photograph focusing on the concrete supporting arch of Ciénega Bridge. File:Sunset Limited Three Bridges Arizona 2014.jpg, alt=Sunset Limited of the Southern Pacific Railroad being pulled over the old El Paso and Southwestern Railroad bridge with Ciénega Bridge (then part of the Dixie Overland Highway) in the background. The photograph was taken in 1921 when the bridge was brand new.,

Sunset Limited The ''Sunset Limited'' is an Amtrak passenger train that for most of its history has operated between New Orleans and Los Angeles, over the nation's second transcontinental route. However, up until Hurricane Katrina in 2005, it operated betwe ...

of the

being pulled over the old EP&SW bridge with Ciénega Bridge in the background circa 1921.

References

External links