page_title: BP Pedestrian Bridge
section_title: Final plan
hierarchical_section_title: BP Pedestrian Bridge / Design / Final plan
caption_attribution_description: English: BP Bridge in Chicago, IL
context_page_description: The BP Pedestrian Bridge, or simply BP Bridge, is a girder footbridge in the Loop community area of Chicago, United States. It spans Columbus Drive to connect Maggie Daley Park with Millennium Park, both parts of the larger Grant Park. Designed by Pritzker Prize-winning architect Frank Gehry and structurally engineered by Skidmore, Owings and Merrill, it opened along with the rest of Millennium Park on July 16, 2004. Gehry had been courted by the city to design the bridge and the neighboring Jay Pritzker Pavilion, and eventually agreed to do so after the Pritzker family funded the Pavilion.
  Named for energy firm BP, which donated $5 million toward its construction, it is the first Gehry-designed bridge to have been completed. BP Bridge is described as snakelike because of its curving form. Designed to bear a heavy load without structural problems caused by its own weight, it has won awards for its use of sheet metal. The bridge is known for its aesthetics, and Gehry's style is seen in its biomorphic allusions and extensive sculptural use of stainless steel plates to express abstraction.
  The pedestrian bridge serves as a noise barrier for traffic sounds from Columbus Drive.
context_section_description: The final design for the bridge was revealed in an exhibit at the Chicago Cultural Center on June 10, 2000. As designed and built, the bridge is 935 feet (285.0 m) long and 20 feet (6.1 m) wide, with a 14-foot-6-inch (4.42 m) Columbus Drive clearance. The clearance was designed to slightly exceed the 14-foot (4.3 m) standard set by the United States Department of Transportation Federal Highway Administration for urban area interstate bridge clearances, and to allow for additional future layers of pavement below.  This height is also greater than the maximum vehicle height of 13 feet 6 inches (4.1 m) set by the Illinois Vehicle Code. According to the Chicago Tribune the width of the "trenchlike" area spanned is approximately 150 feet (46 m), while The New York Times reports the bridge is over ten times longer than Columbus Drive is wide.
  BP Bridge begins in Millennium Park between the trellis system over the Jay Pritzker Pavilion's great lawn and the Lurie Garden; the design was changed so that the west ramp coincided with the boardwalk of the Lurie Garden seam. The bridge winds its way northward along the eastern edge of Millennium Park before crossing Columbus Drive in a C-shaped curve, above underground parking garage entrances. In Daley Bicentennial Plaza the bridge has an S-shape, then turns east. BP Bridge is designed so that its inclined surfaces have a continuous five percent slope rather than landings and switchback ramps, which provides easy access for the physically challenged.  The gently sloped ramp eliminates the need for lifts or any of the other common types of ramps (L-shaped, switchback, U-shaped, straight), and helped the park earn the 2005 Barrier-Free America Award for its exemplary barrier-free design.
  Gehry had hoped to design the bridge so that it could be constructed without a support column in the center of Columbus Drive. However, Chicago Tribune architecture critic Blair Kamin notes that if he had done so, the bridge might not have been as sleek. Building the bridge without the column would have required load-bearing cantilevers (beams supported only on one side) from structural positions on opposite sides of the street; this would have been expensive and labor-intensive, because it would have required excavating large portions of the parking garages on both sides of the street.  Moreover, on the Daley Bicentennial Plaza side, the optimal location for the supporting cantilever would have been at the location of the Monroe Street Garage.  Thus, the preferred bridge design was altered to avoid problems related to the underground parking garages.
  The bridge is both a connector and a viewing platform for the park. It was designed to link the Historic Michigan Boulevard District and the entire Loop to the west with the Lake Michigan lakefront to the east. It was also designed to be a berm noise barrier blocking noise on the eight-lane Columbus Drive from the Park's outdoor band shell (Jay Pritzker Pavilion), by deflecting traffic sounds upward.
  The bridge, which uses steel girders, reinforced concrete abutments and deck slabs, hardwood deck, and a stainless steel veneer, cost between $12.1 and $14.5 million.  It contains large sculptural plates of curvilinear stainless steel instead of more standard flat plates. The bridge's curvilinear design gives it a flowing, natural look, instead of the linear, rigid form of standard bridges.  Although its steel girders rest on concrete pylons and most of the bridge is solid concrete, the bridge uses a hollow box girder design to minimize weight, as the ground that supports the bridge covers underground parking garages.  The concrete base and box girder are flanked by a hollow stainless steel skeleton.  Despite its hollow structure, and the fact that it is designed as a concealed beam bridge, the footbridge is built to highway standards and can support a full capacity load of pedestrians.  The bridge is designed without standard handrails and uses waist-high parapets as guard rails instead.
caption: Crossing Columbus Drive, the bridge is supported by a central concrete column. (from Randolph Street)
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