Jan 17, 2018 By Harry Funk staff Writer hfunk@thealmanac.Net 6 min read

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Harry Funk / The Almanac

Thomas Leech and Linda Kaplan speak at Mt. Lebanon Public Library about their book, “Bridges … Pittsburgh at the Point … A Journey Through History.”

Harry Funk / The Almanac

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Original Point Bridge with the newer version over the Monongahela River in 1927

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The Wabash Bridge over the Monongahela River as it appeared in 1912

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Rather than reams of engineering detail, the design specifications for one of the old versions of the Smithfield Street Bridge addressed the tonnage it could handle.

“Four six-horse teams loaded with 104 bushels of coal had to be able to cross it, or the weight of 100 head of cattle,” Linda Kaplan reported.

She and Thomas Leech, engineers who co-authored “Bridges … Pittsburgh at the Point … A Journey Through History,” spoke about the book at a recent Historical Society of Mt. Lebanon program.

A capacity crowd at Mt. Lebanon Public Library learned about the spans that have crossed the Allegheny, Monongahela and Ohio rivers since 1818, including the three at the Smithfield Street site. The second in the series, the one predicated on the ability to support bovine herds, was built in the 1850s by engineering legend John Roebling, whom history buffs will recognize as the designer of the Brooklyn Bridge.

Leech and Kaplan provided such tidbits throughout the evening as they discussed what their research uncovered about the 34 structures, past and present, spanning the three rivers within a mile of what now is Point State Park.

This year marks the bicentennial of the very first one, which also was the first Smithfield Street Bridge.

“When the bridge was finally completed,” Leech said, “they mounted a cannon on the bridge and launched cannonballs into the Monongahela River. So it was a big deal.”

Like most such structures at the time, the design was the time-tested arch, and it was covered.

“The early bridges were built by the same people who were building farmhouses and barns,” Kaplan explained. “This was the kind of construction that they knew.”

The co-authors proceeded to enlighten the audience further about projects of the 19th and 20th centuries, including:

• Allegheny Aqueduct

• , carrying the Pennsylvania Mainline Canal across the Allegheny at what now is Sixth Street. The structure was Roebling’s initial bridge-building endeavor in the region, and an innovative one, at that.

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“This was the first use of cables in bridge construction, so it was the predecessor of the grand suspension bridges and cable-stayed bridges that you see today,” Kaplan said.

• Point Bridges I and II, crossing the Monongahela near the present site of the Fort Pitt Bridge. The first version was completed in 1877 and was in service for 50 years, until the second opened. Remnants of the latter, which closed in 1959, can be seen in the landings near the Duquesne Incline.
• Third Smithfield Street Bridge

• , in operation since 1883 and designated as a National Historic Landmark.

“One of the interesting things about this bridge: They were somewhat forward-thinking in knowing that maybe someday it would need to be expanded,” Kaplan explained. “So it was designed with that intent. It was one of the first times that was done.”

• Wabash Bridge

• , completed in 1904 and demolished in 1948 after decades of not being used. Its piers still stand on either side of the Monongahela.

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The bridge was part of the Wabash Pittsburgh Terminal Railway founded by George Gould, son of 19th-century railroad baron Jay Gould, a venture that went bankrupt within a few years.

“At the time of its construction, the Wabash Bridge was the longest cantilever truss bridge in the United States and one of the longest of its type in the world,” Leech said. “There was a collapse during construction that killed a lot of workers. It’s still considered the largest construction accident in Pittsburgh history.”

• ”Three Sisters.” The crossings of the Allegheny at Sixth, Seventh and Ninth streets – now named, respectively, the Roberto Clemente, Andy Warhol and Rachel Carson bridges – were built between 1924 and 1928.

In addition to standing as the only trio of identical bridges in the world, they also are distinctive for their self-anchored suspension design.

“There are only a handful of them around the country, six or seven, and three of them are in Pittsburgh,” Kaplan said. “They don’t have the big, wide abutments at the end. The cables actually tie back into the structures to save space.”

• Fort Pitt and Fort Duquesne bridges

• . When planning for the spans in the 1950s, designers faced a major issue.

“It’s something you wouldn’t even think of today, but they didn’t know what to do with the streetcars,” Leech explained. “And somebody said, let’s not put streetcars on the bridge. Without the streetcars, you could flip-flop the direction of traffic and have a much more convenient and passable road system.”

Those were the next-to-last bridges built in the area researched by Leech and Kaplan. The $420 million Veterans Bridge, carrying Interstate 279 over the Allegheny, is the final one.

So far.