Key Bridge (Washington, D.C.)

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Francis Scott Key Bridge
Key Bridge (Washington, D.C.) is located in Washington, D.C.
Key Bridge (Washington, D.C.)
Location US 29 over the Potomac River between Rosslyn, Virginia and Georgetown, Washington, D.C.
Coordinates 38°54′8″N 77°4′13″W / 38.90222°N 77.07028°W / 38.90222; -77.07028Coordinates: 38°54′8″N 77°4′13″W / 38.90222°N 77.07028°W / 38.90222; -77.07028
Built 1923
Architect Nathan C. Wyeth
Max C. Tyler
Architectural style Classical Revival arch bridge
518.5 meters (1,701 ft) long
Governing body State
NRHP Reference # 96000199[1]
VLR # DC Local
Significant dates
Added to NRHP March 1, 1996[3]
Designated VLR October 18, 1995[2]

The Francis Scott Key Bridge, more commonly known as the Key Bridge, is a six-lane reinforced concrete arch bridge conveying U.S. Route 29 traffic across the Potomac River between the Rosslyn neighborhood of Arlington County, Virginia and the Georgetown neighborhood of Washington, D.C. Completed in 1923, it is Washington's oldest surviving bridge across the Potomac River.[4]

History[edit]

The Classical Revival bridge was designed by architect Nathan C. Wyeth and engineer Max C. Tyler. It was built by the United States Army Corps of Engineers between 1917 and 1923, and was named after Francis Scott Key, author of The Star Spangled Banner. The northern terminus of the bridge is just east of the site of Key's Georgetown home, which was dismantled in the late 1940s; near that site, there is now a community park honoring Key.[1][4][5]

The Key Bridge replaced the Aqueduct Bridge. The Aqueduct Bridge was originally built to carry the Chesapeake and Ohio Canal across the Potomac to connect with the Alexandria Canal. After the Alexandria Canal was abandoned, the bridge was converted into a roadway. The Washington abutment still survives and is located west of the Key Bridge. One pier remains and is located in the river near the Virginia shore. On March 1, 1996, the Key Bridge was added to the National Register of Historic Places.[3][4]

The Francis Scott Key Bridge spans the Potomac River connecting Georgetown in Washington, D.C. to Rosslyn in Arlington County, Virginia. The bridge is oriented in a generally north-south direction. The Classically inspired structure is made of reinforced concrete, with eight arches. Five of the arches span over the river, while the other three span land features.

The original structure designed in 1916 and constructed between 1917-1923, included seven arches. The eighth arch was added in 1938-39 in order to span over the George Washington Memorial Parkway in Virginia. The superstructure was altered in 1955 and 1987. The bridge is in excellent condition.

The bridge is 1,791'6" long from the northern edge of the Georgetown approach to the southern edge of the Rosslyn approach. Of the five arches over the Potomac River, the central arch is 208' long, the two adjacent arches have 204' spans, and these are flanked by 187' long arches. The arches over the land include a 152' arch over the George Washington Memorial Parkway in Virginia and a 180' span over K Street and an 82' arch over the C & O Canal on the District side. The central arch rises 85' above the river, while the foundations extend 25' from the water's Surface to the bedrock (when the water is low).

The arches are tripartite in form. Each arch consists of three steel arches which are connected to the concrete foundations. The middle arch is 22' wide and is flanked by smaller 11' wide arches on each side. Wood formwork was laid over the steel for the concrete. The spandrels above each arch were punctured by two, three, or four small arches. The spandrel 1 arches lightened the load carried by the large arches and formed a truss system. The concrete piers have superimposed large Doric pilasters which rise to the bottom of the superstructure of the road deck. The proportions of the arches and the Doric pilasters establish the Classical elements and style.

The original 1923 road deck was 70' wide. It included two 16' wide traffic lanes, a center lane for trolley tracks, and two 8’ wide sidewalks. The original superstructure had a cornice which projected 2' on each side and supported a 4 ' high, 12" thick concrete parapet with 6' long recessed panels on each side. On top of the parapet, at approximately 40' intervals were cast iron light standards. These standards were 7'1" high with a griffin leg and winged shield motif at the base. The eighth arch was added in 1938-39 in order to span over the George Washington Memorial Parkway in Virginia. In 1955, the trolley tracks were eliminated, and the deck was widened from 70' to 80'. The roadway was expanded to 66' wide and the sidewalk was reduced to 5'3" on each side, excluding the vehicular barrier which was also added at that time.

At this time, the concrete parapet and light standards were removed and a new 4' high, cast aluminum railing was installed at the edge of the new deck. A 2' high vehicular barrier was also installed at the edge of the roadway. The light standards were replaced with "cobra arm" light posts, approximately 30' high at 120' intervals.

In 1987, a new post-tension deck was installed, which increased the total width from 80' to 90'. The roadway was maintained at 66' wide, while the sidewalks were widened to 9' 10". At this time, the 1955 alterations were removed, and a new 5’ high protective steel railing was installed at the outside edge of the deck. The railing has 3/4" bars at 4“ intervals, which curve outward at the top. A precast concrete wall was installed at the edge of the roadway to resemble the original 1923 parapet. The new parapet is 2'8" high with 6' long recessed panels. The light fixtures, attached to the top of concrete pedestals, are 14' high and have fluted cast iron posts with acorn light globes. The lampposts are placed above the apex of the arches and at the center of the piers. Despite the widening of the deck, the bridge retains its original design integrity.

Description[edit]

At its southern terminus in Virginia, the Key Bridge connects with North Lynn Street, and via that street with Wilson Boulevard, the George Washington Parkway, Lee Highway (U.S. Route 29), Interstate 66, and State Route 110. At its northern terminus in D.C., the bridge connects with M Street NW, Canal Road NW, and the Whitehurst Freeway, which provides access to K Street downtown. The northbound span has an exit ramp to the eastbound Whitehurst Freeway; however, traffic from the westbound Whitehurst Freeway to the southbound span must use M Street.

The Key Bridge is part of the National Highway System.

Another bridge, also called the Francis Scott Key Bridge (or sometimes the Outer Harbor Bridge), crosses the Patapsco River near Baltimore, Maryland.

The bridge rises just under 100 feet above the Potomac river below (including the height of the railing).

Panoramic view of Key Bridge

See also[edit]

Boats docked beside the Key Bridge in Georgetown

References[edit]

  1. ^ a b "National Register Information System". National Register of Historic Places. National Park Service. 2009-03-13. 
  2. ^ "Virginia Landmarks Register". Virginia Department of Historic Resources. Retrieved 05-12-2013. 
  3. ^ a b "District of Columbia - Inventory of Historic Sites". Government of the District of Columbia. September 1, 2004. Retrieved July 17, 2009. 
  4. ^ a b c Jackson, Donald C. (1988). Great American Bridges and Dams: A National Trust Guide. John Wiley and Sons. pp. 113–114. ISBN 0-471-14385-5. 
  5. ^ "New Memorials Update". National Park Service. March 14, 2001. Retrieved July 17, 2009. 

External links[edit]