Allegheny County will begin a six-year process this month to rehabilitate the Three Sisters Bridges that connect Downtown with the North Shore.
The Roberto Clemente, Andy Warhol and Rachel Carson, given the “sisters” nickname because of their similar designs, will be closed for two years each while crews replace the decking, paint the superstructure and upgrade utilities. In a nod to the historic significance of the bridges, new street lights with a retro look will be installed as part of the projects.
First up: Warhol, the second of the three spans crossing the Allegheny River to open in June 1927. Carson opened in November 1926 and Clemente in September 1928. Warhol received its last upgrade in 1993, when it received deck work and some painting, but this work will be more significant.
“We’re been repairing the decks for some years,” said Steve Shanley, the county’s director of public works. “It’s time for more extensive work.”
The bridges were built within four blocks of each other and are considered the only set of triplet bridges in the country. According to the website Pittsburgh Art Places, they also are important because they were the first to be self-anchored rather than anchored to the ground or abutments and they use eye-bar chains rather than cables for suspension.
The bridges reflect the rich history of spans crisscrossing Pittsburgh’s three rivers, many of the early ones built by private businesses and requiring a toll to cross. Art Places presents this lineage for bridges at the sites of the Three Sisters:
In 1819, the St. Clair Bridge, built where the Clemente Bridge is now, became the first across the Allegheny. That was followed in 1840 by the Hand Street Bridge where the Carson is now.
Later, noted designers became involved. John Roebling, who later designed the Brooklyn Bridge in New York City, built the next generation at the Clemente site in 1859. Gustav Lindenthal built a bridge at the Carson site just before he finished the Smithfield Street Bridge.
By the 1920s, bridges had become public entities. That meant designs had to be approved by the Pittsburgh Art Commission, encouraging more elaborate features, and to meet clearance standards for river navigation.
Chief engineer Vernon R. Covell and architect Stanley L. Roush designed the Three Sisters for the county Department of Public Works, incorporating fancy lights and other art elements into their look. As a result, the American Institute of Steel Construction named the first one the Most Beautiful Steel Bridge of 1928.
Mr. Shanley said Brayman Construction Corp., which won the $25.4 million contract to upgrade Warhol, will incorporate some of that 1920s history into the bridge rehabilitation. For example, the bridge will have dual lanterns like the original Clemente bridge design and light fixtures on pylons to match the original Warhol.
But most of the improvements will be utilitarian, such as installing a 9-inch steel reinforced deck; placing sloped plates along the walls to prevent sitting water that causes rust; replacing all expansion joints; repairing the substructure, including a concrete retaining wall; and repainting everything in the same Aztec gold. In addition, the bridge will be converted from four lanes of 8.25 feet to to three, 11-foot lanes, one in each direction with a turning lane in the middle.
Workers also will include framework for decorative lighting that nonprofit Riverlife hopes to install in the future on all three bridges.
The bridge will be closed to traffic and pedestrians until its expected completion for Light Up Night in November 2017. The Rachel Carson Bridge is the main detour and off-duty police officers will be used to help move traffic.
The detour will reroute about 350 Port Authority buses a day to Carson, spokesman Adam Brandolph said. The detoured routes will be routes 1, 2, 4, 6, 7, 8, 11, 12, 13, 15, 16, 17 and the O5.
Mr. Shanley said the plan is to rehab Carson in 2018 and Clemente in 2020.
Ed Blazina: eblazina@post-gazette.com or 412-263-1470.
First Published: August 1, 2016, 4:00 a.m.
