History of the Sister Bridges

The first bridge to cross the Allegheny River in the City of Pittsburgh, the wooden St. Clair Bridge, is designed by Lewis Wernwag and built for $80,000 on Sixth Street – the current site of the Roberto Clemente Bridge.

The covered, wooden Hand Street Bridge is built by the Pittsburg & Allegheny Bridge Company on Ninth Street – the current site of the Rachel Carson Bridge.

The St. Clair Bridge is replaced at Sixth Street by a wire suspension bridge for just less than $300,000. It’s designed by John Roebling, who also designed the Brooklyn Bridge.

The first bridge at Seventh Street – the current site of the Andy Warhol Bridge – is built. It is designed by Gustav Lindenthal just before he completes the Smithfield Street Bridge.

The Hand Street Bridge on Ninth Street is replaced at Ninth Street by a steel and wrought-iron truss bridge designed by Gustave Kaufman and George Ferris. A year later, Ferris began designing what he is better known for – the Ferris Wheel.

A third bridge at Sixth Street is built for $560,000 after the previous structure was deemed to be inadequate for heavier trolley loads. That metal truss bridge was designed by Theodore Cooper.

Congress passes the Rivers and Harbors Appropriation Act of 1899, requiring the Secretary of War to declare bridges over navigable bodies of water in violation if they pose “an unreasonable obstruction” to the free navigation of such waters because of insufficient height or span width.

During the latter half of the 19th century, there was a big lobbying effort to make the bridges at Sixth, Seventh, and Ninth Street toll free. After much negotiating between Allegheny County, the City of Pittsburgh, and other interests, the bridges were taken over by the county finally made free to the public.

U.S. Secretary of War Newton Baker found that the bridges at Sixth, Seventh, and Ninth Street were not in compliance with the Rivers and Harbors Appropriation Act of 1899. Because of the importance of Allegheny River traffic and Pittsburgh’s steel production, Baker wrote that the immediate elevation and relocation of the bridges’ piers was in the national interest. He then imposed a deadline to remedy the issue, and Allegheny County got to work designing what would become the Sister Bridges.

Allegheny County voters approve a $29.2 million bond issue to improve bridges and municipal structures.

The initial designs for new bridges at Sixth, Seventh, and Ninth Street are approved by the federal government and the local planning departments, but the City of Pittsburgh’s art commission disapproves of the plans. They want more aesthetically pleasing bridges that would provide better views of the city, so Allegheny County engineers are forced to go back to the drawing board.

For design ideas, Allegheny County engineers refer to the book “Movable and Long-Span Steel Bridges” by George A. Hool and William Spaulding Kinne, which was published in 1923. Within it, they notice the Cologne Chain Bridge, which was built 1915 and crosses the Rhine River in Germany. Its design is well suited for areas where there was unstable soil, such along as the Allegheny River.

Architect Stanley L. Roush, chief engineer Vernon R. Covell, design engineer A.D. Nutter, and consulting engineer T.J. Wilkerson then submit a new design to the stakeholders, who approve of the change. This time, all three bridges will be identical – hence the nickname Sister Bridges. In fact, the Sisters Bridges are the only trio of identical bridges in the world. They also are the first self-anchored suspension bridges built in the United States. Other than the Sister Bridges, only two other self-anchored suspension bridges are still in use in the country – the San Francisco-Oakland Bay Bridge and the William O. Lee Memorial Bridge in Frederick, Maryland.

Allegheny County awards the American Bridge Company the contract to build the Sister Bridges. Crew begin building what is now called the Andy Warhol Bridge.

Construction of what is now called the Rachel Carson Bridge begins.

The Seventh Street Bridge – now called the Andy Warhol Bridge – is completed. It is a moment of great celebration, which included a parade of dignitaries to officially dedicate the new structure.

The Ninth Street Bridge – now called the Rachel Carson Bridge – opens to similar fanfare.

Unlike the Seventh and Ninth Street Bridges, the old Sixth Street Bridge was reused. It was placed on barges and floated to Neville Island, where it would become the Coraopolis Bridge.

Construction of what is now called the Roberto Clemente Bridge begins. That work occurs after the other two Sister Bridges were opened to ensure that residents would always have a safe river crossing available.

The Sixth Street Bridge – now called the Roberto Clemente Bridge – opens.

The new Sixth Street Bridge receives the Most Beautiful Steel Bridge Award from the American Institute of Steel Construction. The unveiling of the award took place in December in the Gold Room of the County Courthouse.

The Sister Bridges are painted Aztec Gold.

The Sister Bridges are added to the National Register of Historic Places.

The Sister Bridges are designated as architecturally significant structures by the Pittsburgh History and Landmarks Foundation.

In an effort to improve the region’s image nationally, several local agencies and organizations commission a study to determine the feasibility of installing enhanced lighting on 11 bridges within the City of Pittsburgh, including the Sister Bridges. They also host a two-day event called “Light the Bridges” that includes temporary installation of uplighting on what is now called the Roberto Clemente Bridge.

Allegheny County officials begin renaming each of the Sister Bridges after historic and impactful people with ties to the area. To coincide with construction of nearby PNC Park, the Sixth Street Bridge is renamed the Roberto Clemente Bridge to honor the Pittsburgh Pirates legend.

The Sister Bridges are added to the Historic American Engineering Record.

Blue disk lights are installed on the Roberto Clemente Bridge suspension chain pins along with hanger and tower uplighting, replica luminaire fixtures on the pylon, and replica roadway lighting fixtures.

The Seventh Street Bridge is renamed the Andy Warhol Bridge to honor the world-famous artist and in celebration of the 10th anniversary of The Andy Warhol Museum located two blocks away.

The Ninth Street Bridge is renamed the Rachel Carson Bridge on Earth Day to honor the renowned environmentalist and author of the influential “Silent Spring.”

A temporary lighting installation on the Rachel Carson Bridge called Energy Flow is commissioned for the City of Pittsburgh’s bicentennial. The collaboration between environmental artist Andrea Polli and Ron Gdovic of WindStax, a Pittsburgh-based wind turbine manufacturer, was so popular that the installation was extended. Over 27,000 multicolored LED lights positioned along the bridge’s vertical hangers showed a real-time visualization of wind speed and direction as captured by a weather station located on the bridge. Following the success of Energy Flow, County Executive Rich Fitzgerald tasks the county’s Department of Public Works with investigating the possibility of installing permanent enhanced lighting on the Sister Bridges. The county contracts with Michael Baker International to formulate options. Once complete, the county invites several stakeholders, including the Pittsburgh Downtown Partnership, Pittsburgh History and Landmarks Foundation, Office for Public Art, and Riverlife, to provide input and discuss the options before a final design decision is made.

A $25.6 million Andy Warhol Bridge rehabilitation project is completed. It involved repairs to the structural steel, repairs to the concrete/masonry substructure, replacement of the concrete deck and sidewalks, replacement of the expansion dams, refurbishment of the pylons, repairs to the stairs on the downtown side, improvements to drainage, repainting of the bridge and handrails Aztec Gold, replacement of the navigational lighting, replacement of the street lighting to resemble its original appearance from the 1920s, and replacement of utility lines under the bridge.

A $24.9 million Rachel Carson Bridge rehabilitation project is completed. It involves repairs to the structural steel, repairs to the concrete/masonry substructure, replacement of the concrete deck and sidewalks, replacement of the expansion dams, refurbishment of the pylons, repairs to the stairs on the downtown side, improvements to drainage, repainting of the bridge and handrails Aztec Gold, replacement of the navigational lighting, replacement of the street lighting to resemble its original appearance from the 1920s, and replacement of utility lines under the bridge.

A new LED enhanced lighting system on the Sister Bridges officially debuts for the first time in front a large crowd during the Pittsburgh Downtown Partnership's Light Up Night festivities. The system includes 2,628 feet of linear fixtures on the bridges’ vertical suspenders; 192 rounded fixtures on the suspension chain pins; 132 spot and wash lighting fixtures that accent the towers, hangers, and piers; as well as 12 replica fixtures atop the pylons. The first light display is a commissioned design created by Rob Long called Observing Light. It features a series of video images of light reflections captured along the Allegheny, Monongahela, and Ohio Rivers and displayed on the bridges’ vertical suspenders. The bridges’ other lighting elements are illuminated in soft, warm light that support the colors shown on the suspenders.

A $36.3 million Roberto Clemente Bridge rehabilitation project is completed. It involves structural steel and concrete/masonry repairs; replacement of expansion dams, decks, sidewalks, stairs, utility lines, street and navigational lights, pavement markings, signage, and delineators; refurbishment and cleaning of the pylons and piers; repainting of the bridges and handrails; placement of rock scour protection; and installation of an enhanced lighting system. Reopening of the bridge is celebrated with a ribbon-cutting during the Pittsburgh Cultural Trust's First Night festivities. It is attended by State Senator Wayne Fontana, County Executive Rich Fitzgerald and family, Mayor Ed Gainey, Roberto Clemente Jr. and family, Roberto Clemente Museum Executive Director Duane Rieder, Pittsburgh Cultural Trust President and CEO Kendra Whitlock Ingram, and county officials.