1. Bridges of Pittsburgh
By Jonathan Skoner

2. Fact
By the 1930s Pittsburgh in the valleys and hills of Allegheny County in western Pa had more bridges than any comparable place in the world.

3. Why does Pittsburgh have so many Bridges?
Pennsylvania is really an ancient plateau
It was carved away over hundreds and thousands of years by rivers that were searching their way to the Gulf of Mexico

4. Prime Location
Because of the Mountains and the headwater of the Ohio River -- Pittsburgh was able to ship timber, oil, coal, glass, iron, and steel to almost anywhere

5. Because of Pittsburgh’s growth the city became well known in America
All over America - states, cities, and companies turned to Pittsburgh for things needed

6. Because of Pittsburgh’s growing industry, Pittsburgh was able to supply America with steel to build things
Some things that contain Pittsburgh steel are the Brooklyn Bridge, the Washington Monument, the Eads Bridge crossing the Mississippi at St. Louis, the first skyscrapers in Chicago and New York, and in the railroads crisscrossing the American West

8. During the various wars of the country Pittsburgh quickly supplied the military with and endless supply of war materials all over the world. Some of these products were -- cannons and cannon balls

9. After the 1850s railroads began to appear in Pittsburgh
With the combination of railroads, mountains, and bridges Pittsburgh became the busiest industrial state in America

10. Because of Pittsburgh’s effort in bridge production Pittsburgh was recognized by many famous companies for designing and building bridges
Between 1924 and 1932 Allegheny County built 99 bridges
Also, Bridge Engineers were attracted to Pittsburgh from all over the world because of the challenging terrain of Pittsburgh

11. Challenges Some challenges that engineers were presented with were –
Getting the first rope across the river to begin building
In the older days a row boat was sometimes used or even shooting it across with a bow and arrow
Today helicopters and cranes are used
Another challenge was getting a strong foundation for bridges. When bridges were being built columns and piers were used as supports. The supports had to be dug down deep enough into the ground so that they had firm footing such as an underlying strata of rock, sand, or satisfactory soil
Today Hollow cylinders are dropped into rivers and hydraulic pumps were used to dewater an excavation allowing workers to dig even deeper

12. Ambridge
What was it named after?
American Bridge Company

13. American Bridge Company
Formed in the 1900s by the same interests that controlled the United States Steel Corporation
Was an attempt to monopolize the nation's bridge-building industry
Within years after its founding American Bridge Company was able to claim over half the structural-steel fabricating capacity of the country
In its early years it depended on affiliated firms to erect its bridges
After the 1920s the company was able to build bridges on its own without any assistance
After 1904 their company headquarters were located in Pittsburgh
Now they have headquarters in: Bristol, TN
Chicago, IL
Coraopolis, PA
Long Beach, CA
New York, NY
Orlando, FL
Reedsport, OR
Tampa, FL
Williamsburg, VA
“Although never in complete control of the bridge market, the American Bridge Company supplied a substantial portion of the steel bridges purchased by state and local highway officials in the early 20th century, and there can be no doubt that the company was the single most important fabricator of the period.”(Notable Bridge Designers and Builders of Connecticut, Builders)

14. Iron
The first iron was used in bridges in the late 18th century. One of the first iron bridges was built in Brownsville East of Pittsburgh

15. John Roebling
Inventor of iron rope/cable in the 1840s for the Pennsylvania Canal which crossed the Allegheny Mountains to reach Pittsburgh
Roebling had figured out how to spin and wine wire into a tight rope
The wire rope changed the technology of the suspension bridges forever
The strength of the iron rope was much stronger that the fiber rope previously used and therefore led to the building long suspension bridges
In the 1870s steel replaced the wire rope and made even more possible for longer bridges to be built.

16. Aluminum
Strong and Lightweight material that started to be used in the 1930s.
Aluminum was important because it decreased the weight of bridges that were built
In 1934 the Smithfield St. bridge was one of the first Bridges to use Aluminum--- It replaced its old wrought iron floor supports and installed new aluminum decking

17. COMPUTER-ASSISTED DESIGN (CAD)
During the late 1960s CAD made it possible for bridge engineers to make electronic models of bridge designs
The computer greatly influenced the building of bridges - The high speed analyzing of the computer was saved a lot of time when designing of bridges

18. The Fort Pitt and Fort Duquesne bridges were among the first bridges to ever be built with Computers

19. Bridge Engineers John Roebling (1806 – 1869)
The greatest bridge engineer of the 19th century
Famous for the Brooklyn Bridge
Started his career in Pittsburgh
It is believed that he got his thoughts on the wire rope after watching the building of the Pennsylvania Canal. He saw many men die while they worked because of the rope they were using broke.
Roebling’s first success was in building a replacement bridge for the old canal bridge that crossed the Allegheny River at Eleventh Street
He finished the bridge in 1844 after only a stunning 6 month construction
Other major bridges that he built with his wire rope were the second Monongahela St. Bridge in 1846 and the suspension bridge at 6th street
Best known for the Brooklyn Bridge in New York. However, he died during the construction due to injury and his son finished building.

20. Bridge Engineers Gustav Lindenthal (1850 – 1935)
Famous for the Simthfield St. Bridge
A.K.A. “Dean of bridge engineers”
The National Historic Landmark – Smithfield St. Bridge was his first major bridge
The Smithfield St. Bridge of 1881 – 1883 is known today as the oldest steel bridge in the United States
Lindenthal’s second most famous bridge is the 7th St. Bridge of 1884 – 1927 where he used a double set of wire cables
Just as Roebling did Lindenthal moved on to larger and stronger bridges
In 1907 he designed the Queensboro Bridge that crosses the East River in New York City

21. Bridge Engineers George Richardson (1896 – 1988)
A key piece in Allegheny Bridge building from 1924 – 1937 – A large growth time for Allegheny
A draftsman with American Bridge Company and later joined the county works department
He helped on many of the major bridges in Pittsburgh by assisting in the design of them
Some works of his were – McKees Rocks and West End Bridges, Westinghouse Memorial Bridge, Liberty Bridge, the second Point Bridge, the South Tenth Street Bridge, and the Homestead High Level Bridge
Later started his own company called “Richardson, Gordon and Associates” which later became part of “HDR Engineering Inc.”
Started trend of using acronyms as names of companies

22. International Bridge Conference Awards
The three awards given out each year at the conference are the:
George S. Richardson Medal – single recent, outstanding achievment
John A. Roebling Medal – lifetime achievement in bridge engineering
Gustav Lindenthal Medal – a bridge with an aesthetic merit component erected within the last 100 years

23. Underground Bridge
Built in 1897 crossing the St. Pierre’s Ravine to get people to the entrance of the Carnegie Library
In 1913 the ravine was filled and the bridge was covered because the city wanted a parking area between the newly built Forbes Field and the Carnegie Library
The dirt and rocks that were used to fill the ravine was from the removal of the hump on Grant Street
The bridge is still there

24. The First Smithfield St. Bridge 1818 – 1845 (a. k. a. Monongahela St
The First Smithfield St. Bridge – 1845 (a.k.a. Monongahela St. Bridge)
Built in 1818
Designed by Lewis Wernwag
The first bridge in the city of Pittsburgh
1500 feet long and had 188 foot spans
Had tool booths at both ends of the bridge
Covered bridge
Burned down in the Great fire in April of 1845

25. The Second Smithfield St. Bridge 1846 - 1843
Built in 1846 on the same piers of the earlier Smithfield St. Bridge
Bridge engineer – John Roebling
Wire Cable Suspension Bridge
Took 7 months to build
Came down in 1883 when its replacement was opened

26. The Third Smithfield St. Bridge 1883 – Present Day
Built from 1881 – 1883
Built By Gustav Lindenthal who also designed the Seventh St. Bridge (1884 – 1925)
One plaque that is on the South Portal of the bridge: PITTSBURGH OUTSTANDING ACHIEVEMENT AWARD SMITHFIELD STREET BRIDGE REHABILITATION PROJECT

27. South Twenty-Second Street Bridge (Brady Street Bridge)
Built from
Built by the Schultz Bridge and Iron Co. of Pittsburgh
steel-riveted, through-highway bridge
the second to be owned by the city and the first free bridge in Pittsburgh

28. Veterans Bridge Bridge Type: Steel, welded girder
Built from 1986 – 1987
Built by PennDot

29. THREE SISTERS BRIDGES Bridge Types: Self-anchored Suspension bridge
Roberto Clemente Bridge
Built from 1925 – 1928
Built by Allegheny County
Seventh St. Bridge
Built from 1925 – 1926
Ninth St. Bridge
Built From 1925 – 1928
site conditions did not allow for typical anchorages.