Friday, July 15, 2022

1928 Liberty Street Bridge over Monongahela River and 1924 Tunnels in Pittsburgh, PA

Tunnel: (Bridge Hunter; pghbridges; Satellite: North Portal, South Portal)

HAER PA,2-PITBU,64--12 (CT)
3/4 VIEW FROM RIVERBANK, FROM SOUTH. - Liberty Bridge, Spanning Monongahela River, East Carson Street & Second Avenue at State Route 3069, Pittsburgh, Allegheny County, PA

On the left side of this image you can see the concrete retaining wall above the tunnel's north portal. Also of interest is that there are still some industrial buildings along the river.
Street View

 On the left side, you can see some of the concrete of the tunnel portals.
Street View

North Portal
Street View

South Portal
Street View

"This 2,663'-0", sixteen-span, $3.7 million Pratt deck truss bridge was the longest and most expensive bridge built in Allegheny County when it was completed in 1928. The bridge features two 450'-0" cantilevered main spans with suspended sections over the Monongahela River and deck girder approach spans on either side. The bridge links Pittsburgh's downtown area with the Liberty Tunnels, built through Mt. Washington in 1924. The opening of the tunnels and the bridge were instrumental in the development of Pittsburgh's South Hills suburbs. The Liberty Bridge was listed in the National Register of Historic Places in 1988." [HAER-data]

This photo of the Panhandle Bridge also has a good view of the Liberty Bridge and North Portal.
BrooklineConnection via Dennis DeBruler, License: Creative Commons Attribution-Share-Alike (CC BY-SA)

The 5,889' Liberty Tubes penetrate the 400' high, 5-mile long Mount Washington and provide access to the South Hills. [pghbridges-bridge, pghbridges-tunnel]
Postcard via BridgeHunter-bridge

I have not found out what work was being done on the bridge to cause it to be shrouded in tarps. But I presume this image was taken around 2016 because a fire in the tarps caused the bridge to be closed Sep 2, 2016. 30' of the truss was damaged, including a buckled compression member. [cbsnews]
3D Satellite

The tunnels were completed in 1922, but the opening was put off until 1924 after a ventilation solution was added. That solution was not adequate so vertical shafts were added at the midpoints to a ventilation building on top of Mt. Washington. "Carrying 25,000 vehicles in 1932, the Tubes were over their designed capacity. In 2000, the average daily traffic was 63,027." A proposal for an interchange between Saw Mill Run Blvd. and West Liberty Av. was made in 1919. An interchange was finally built in 1999. [phgbridges-tunnel]

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