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speeches. Several South Hills communities declared a half-holiday for the event, and flags and bunting were draped over several buildings along the parade route. [19]

Many South Hills businesses took out advertisements in the Pittsburgh Post-Gazette the following day, celebrating the bridge's opening and noting that it would make their businesses more accessible to the public. Several hundred vehicles that had begun the procession in Mt. Lebanon did not reach the bridge until well after the conclusion of the ceremony. Aerial bombs and fireworks accented the celebration. A photograph taken during the procession shows the bridge decorated with American flags and hundreds of Model-T Fords packed onto the deck. [20] It was the largest automobile procession in Pittsburgh history.

The bridge's construction struck a significant blow at the streetcar, which began a slow and irreversible decline from that point onward. It was thus symbolic that during the grand opening ceremonies, city-bound streetcars were delayed for nearly an hour waiting for the procession to pass.

Bridge Details

When it opened, the Liberty Bridge was the longest, highest, and most costly span yet built in the city. Its 2,663'-0" total length includes lengthy approaches on either side. [21] Most visually striking are its two 450'-0" river spans, whose profiles resemble arches but are actually cantilevered from the piers with a minimum vertical clearance of 50'-0" [22] Extending from cantilever arms of each of these spans are small suspended spans -- ordinary trusses -- in the middle. These cantilevers rest upon three reinforced concrete piers with granite facing. These piers were built using caissons, are anchored in the riverbed, and provide a 450'-0" clear width for navigation. [23]

The bridge's roadway, as originally constructed, was asphaltic concrete, 38'-0" between curbs. The roadway spans the Monongahela River and portions of land on either side, including six streets and three railroad lines. The bridge extends from the downtown area on a 1.6 percent ascending grade to the Liberty Tunnels. At its highest point, the bridge rises 113'-0" above the river.


19] "City, County Join in bridge Exercises Today,'' Pittsburgh Post-Gazette (27 Mar. 1928), L

20] Pittsburgh Post-Gazette (28 Mar. 1928), 1.

21] Measured from the north portals of the Liberty Tunnels to Forbes Street, the bridge's length is 3,657'-0", 2,667'-0" of which is over land and 990' -0", of which is over the river.

22] The cantilever method of construction was also used for the Washington Crossing Bridge over the Allegheny River, completed in 1924. At $2,345 million, that bridge was the most costly Pittsburgh span until the completion of the Liberty Bridge. See U S. Department of the Interior, HAER No. PA-447, "Washington Crossing Bridge" 1997, Prints and Photographs Division, Library of Congress, Washington, D.C.

23] The piers supporting the approaches are built of reinforced concrete on the south side, but are steel bents on concrete foundations under the northern approach.



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HAER No. PA-448
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At the northern approach, the central roadway of the bridge passes under the Boulevard of the Allies to Forbes Street, while two 44'-0"-wide ramps, or driveways, connect at grade with the boulevard in either direction. Another ramp, connecting the central roadway with Bigelow Boulevard over Fifth Avenue and Forbes Street, was built later. The northern approach's connection to Forbes Street required an 80'-0" deep cut into the hillside, the removal of approximately 108,000 cubic yards of earth and shale, and the erection of a 70'-0"-high, 18"- to 36"-thick reinforced concrete wall built on a 1:4 slope just west of the hilltop Duquesne University campus. The wall was anchored to its sloping bed of earth by steel bars placed on 4'-0" centers. Had the concrete wall been built vertically, rather than sloped, it would have required a 65'-0"-thick wall. [24] On its south side, the bridge roadway meets a traffic circle before the entrance to the Liberty Tunnels, with roads connecting to the Mt. Washington (now McArdle) Roadway and Brownsville Avenue.

The total cost came to $3.436 million -- $335,000 less than the original $3.771 million allocation provided by the 1924 bond measure. This total cost included damages paid out to owners of affected property, including the Pennsylvania Railroad. Over twenty-one different contracting companies worked on the structure, and approximately thirty different contracts were let during the course of its erection. Eleven thousand tons of steel were used in the superstructure.

The completion of the Liberty Bridge marked only the latest of a flurry of bridges built by the county since 1924, including the Three Sisters (Sixth, Seventh, and Ninth streets), Washington Crossing, and New Kensington bridges over the Allegheny River, and a new Point Bridge over the Monongahela. Five more were scheduled for completion in 1928. One source, however, proclaimed the Liberty Bridge to be the "most picturesque" of these county bridges. [25] The Liberty Bridge, in conjunction with the tunnels and the Mt. Washington Roadway (which was completed in mid-1928), represented a total public works expenditure of $10.492 million.

Developing the South Hills

While the bridge was a major achievement for Pittsburgh, it had its most significant impact on the South Hills area. Like other suburban developments of the 1920s in American cities, the new roads for automobiles around the South Hills permitted development over a wider area than was stimulated by the trolley, whose fixed route allowed for a predominantly fingerlike settlement pattern typical of late-nineteenth-century American streetcar suburbs. [26] Yet the


24] Allegheny County Commissioners' Office, "Liberty Bridge Approach," 3 Feb. 1928, vertical files, Allegheny County Office of Records Administration, Pittsburgh, Pa.

25] Pittsburgh Press (25 Mar 1928), vertical files, Allegheny County Office of Records Administration, Pittsburgh, Pa.

26] Kenneth T. Jackson, Crabgrass Frontier: The Suburbanization of the United States (New York: Oxford Univ Press,1985), 181.



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Liberty Bridge's opening did not mark the initial penetration of Pittsburgh's South Hills, nor did it stimulate its initial development.

The story of the South Hills extends back at least fifty years prior to the bridge's construction, as real estate speculators scrambled to find open land around the industrial mecca of Pittsburgh spreading along the Monongahela River's south shore. The very geography of the place, with steep hills rising up from the embankments, isolated the South Hills from the city. [27]

The first mode of transportation to penetrate the South Hills arrived in 1869, with the construction of the Monongahela Incline extending from the banks of the Monongahela River to the top of Mt. Washington. Real estate developers seized the opportunity to develop the South Hills area following the incline's construction, convincing county officials to approve the laying of tracks for their newly established Pittsburgh and Castle Shannon Railroad. This railroad connected the drop-off point of the incline to Castle Shannon five miles away.

Settlement along the railroad was not extensive, but the South Hills area continued to expand, however slowly, following the completion of the Duquesne Heights Inclined Plane in 1877. A trolley line that wound along Sawmill Road and up the slopes of Mt. Oliver, built in 1888, also contributed to settlement.

It was not until 1904, however, following the completion of the Mount Washington (South Hills) Transit Tunnel, that the South Hills began to truly develop. This tunnel allowed trolleys to travel from downtown Pittsburgh, across the Smithfield Street Bridge, to the South Hills Junction stop on the east side of Mt. Washington. From there, trolley lines extended to a number of areas in the South Hills, and the area's development took off [28]

Thus, before the South Hills became automobile suburbs, they had been inclined plane suburbs, railroad suburbs, and streetcar suburbs. The trolley initially stimulated the development of Mount Lebanon, Dormont, Brookline, Brentwood, Whitehall, and Castle Shannon, and in 1924, with the completion of the Liberty Tunnels (known locally as the Liberty Tubes), this development began in earnest and the real estate values in the South Hills increased significantly. Two days before the opening of the bridge, an article appeared in the Pittsburgh Press discussing the value of the new project to the South Hills. The article noted that in 1918, property values in Mt. Lebanon, for example, totaled $3.783 million. By 1928, that figure had increased to $14.5 million. The article attributed this increase directly to the tunnels and the bridge:

To reach their place of employment or the metropolitan business district, residents of the South Hills merely step into the car and within a few minutes are in the heart of the Golden Triangle.... The county commissioners have actually moved

the suburbs nearer the central business district by 10 to 20 minutes. A detour over hills, far beyond the direct goal of the urbanites, is no longer necessary. [29]

Index of Photographs

Page created:
Last modified: 27-Mar-2002

HAER Text: J. Philip Gruen, August 1997; Pennsylvania Historic Bridges Recording Project - I
visit site - "American Memory" at Library of Congress
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