The Tufa Bridges are two bridges made of tufa stone located in

Schenley Park Schenley Park () is a large municipal park located in Pittsburgh, Pennsylvania, between the neighborhoods of Oakland, Greenfield, and Squirrel Hill. It is also listed on the National Register of Historic Places as a historic district. In 2011, th ...

Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

. Built in 1908 by George W. Burke, the bridges currently serve as part of a footpath within the park.

History

The idea for the construction of the two bridges came from George Burke, who was the Superintendent of City Parks for the

Department of Public Works This list indicates government departments in various countries dedicated to public works or infrastructure. See also * Public works * Ministry or Board of Public Works, the imperial Chinese ministry overseeing public projects from the Tang ...

. Burke had no prior experience in architecture, engineering, building, or designing, but rather he was a

horticulturist Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...

and city official. Burke was a Pittsburgh native and entered into work with the City of Pittsburgh in 1890 as a park foreman. In 1903 the parks became a separate bureau of the Department of Public Works, and with that change Burke was hired as parks superintendent. From this position he was responsible for maintaining

Phipps Conservatory Phipps Conservatory and Botanical Gardens is a botanical garden set in Schenley Park, Pittsburgh, Pennsylvania, United States. It is a City of Pittsburgh historic landmark and is listed on the National Register of Historic Places. The gardens wer ...

and Schenley Park. Phipps Conservatory, which is also located in Schenley Park, was made possible through a gift from

Henry Phipps Jr Henry Phipps Jr. (September 27, 1839 – September 22, 1930) was an American entrepreneur known for his business relationship with Andrew Carnegie and involvement with the Carnegie Steel Company. He was also a successful real estate investor ...

, and under Burke it became world famous for its flower shows. Up until his death, Burke made significant improvements to both Schenley Park and Phipps Conservatory, including the construction of the two tufa bridges. Burke chose the bridge locations in a dark and shady area of the park so as to make sure that

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

and

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Victorian-era In the history of the United Kingdom and the British Empire, the Victorian era was the period of Queen Victoria's reign, from 20 June 1837 until her death on 22 January 1901. The era followed the Georgian period and preceded the Edwardi ...

style park. Construction began in March 1908, and Burke oversaw the entire project. The bridges extended the bridle path across the hillsides and Nature Ravine, Phipps Run. The bridges were finished and opened up to the public in early 1909. The bridges continue to operate as part of the walking trails in Schenley Park, with only minor repairs needing to be made to replace and repair some tufa stones in 2010. The bridges were nominated in August 2017 to become a City Historic Landmark b
Preservation Pittsburgh

Architecture

The bridges were designed by George Burke in the Rustic or Romantic

Arch Bridge An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side. A viaduct ...

architectural style. What is most significant about the architecture of the bridges is the method of construction and materials used. The body of the bridge was made with

reinforced concrete Reinforced concrete (RC), also called reinforced cement concrete (RCC) and ferroconcrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having hig ...

with steel rods. The tufa stones came from a quarry in Northeastern Ohio. The concrete was poured into a frame with the tufa built up into a mold on the sides, and then after the concrete hardened to the tufa, the frame was removed. These tufa bridges are the only bridges in the world made in this style with tufa stones. The tufa stones themselves also give the bridge a unique look. The stone cladding on these bridges has overtime become unnaturally blackened.

Geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...

s have speculated two different reasons for this. The first being that the

coal dust Coal dust is a fine powdered form of which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal. It is a form ...

that was abundant in Pittsburgh during the mid-twentieth century caused the darkening, and the second being that the darkening is a result of manganese oxidation.Wilbur Stout, “Marl, Tufa Rock, Travertine, and Bog Ore in Ohio,” Geological Survey of Ohio, Fourth Series Bulletin 41 (1940): 12. This darkening of the tufa stone makes the bridge visually unique, and the construction with tufa stones makes in architecturally unique.

Gallery

File:Tufa Bridge, Schenley Park, 2015-09-19, 02.jpg, Tufa Bridge today from above path File:Tufa Bridges 2.jpg, View of Tufa Bridge from the past File:Tufa Bridges 4.jpg, Old photo of Tufa Bridge from above

History

Architecture

Gallery

References