By using this site, you agree to its use of cookies as provided in our policy.

Smithfield Street Bridge - Pittsburgh, PA
Posted by: Groundspeak Regular Member onfire4jesus
N 40° 26.407 W 080° 00.165
17T E 584576 N 4477085
Quick Description: The Smithfield Street Bridge was the first bridge in America to use the lenticular - or lens-shaped - truss design; and it was one of the first major bridges in the U.S. built primarily with steel. It carries Smithfield St across the Monongahela.
Location: Pennsylvania, United States
Date Posted: 4/16/2008 2:14:06 PM
Waymark Code: WM3KKZ
Published By: Groundspeak Premium Member QuesterMark
Views: 61

Long Description:

From the ASCE web site:
"Three rivers - the Allegheny, Monongahela, and Ohio - join in Pittsburgh, making the city a natural site for the building of bridges. But the Smithfield Street Bridge stands apart from other Pittsburgh bridges for several reasons: it replaced structures by two well-known bridge engineers, Lewis Wernwag and John A. Roebling; it was the first use in America of the lenticular - or lens-shaped - truss design; and it was one of the first major bridges in the U.S. built primarily with steel.

The Smithfield Street Bridge also is significant because it was designed by the renowned engineer and bridge designer Gustav Lindenthal, who was only 32 years old when he conceived it. The graceful appearance of the bridge's twin 360-foot spans foreshadowed a new approach to bridge-building-when Lindenthal became commissioner of bridges for the city of New York in 1902, he initiated the formal practice of engineers and architects collaborating on all major bridge projects.

Facts

Lindenthal originally specified Bessemer steel -- made in blast furnaces -- for the Smithfield Street Bridge, but later decided on open-hearth steel, manufactured locally, because it could be made more uniformly and of higher quality. Other bridges for which Lindenthal is known include the Hellgate Bridge over the East River and the Queensborough Bridge, both in New York City.

The Smithfield Street Bridge was built on piers constructed in 1880 for a previous project that had been planned and then abandoned by the company responsible for the constuction and operation of the bridge. By building on the downstream side of piers and designing a detachable sidewalk on the upstream side, Lindenthal provided for the bridge's eventual expansion from its original 48-foot width.

In 1889, a second deck was added to the Smithfield Street Bridge to carry horse-drawn streetcars; ten years later, the deck was widened to accommodate electric trolleys. In 1911, the tolls were removed, and in 1915, the original wrought iron portals were replaced with replicas made of cast steel.

A thorough renovation in 1933 replaced the bridge's steel floor system with structural aluminum beams and prefabricated aluminum decking.

A second renovation, in 1996, increased the bridge's load limit from three to 23 tons. It also restored the bridge's original color scheme -- including royal-blue trusses and sandstone-yellow portals -- while replacing the six copper finials that crown the elaborately decorated portals.

Another well-known bridge using the lenticular truss design in a double span is the Saltash Railway Bridge across the River Tamar in Cornwall, England, designed by noted engineer Isambard K. Brunel in the late 1850s.

Location:
Smithfield St across the Monongahela River in Pittsburgh, PA


Type of structure/site: Bridge

Date of Construction: 1883

Engineer/Architect/Builder etc.: Gustav Lindenthal

Engineering Organization Listing: American Society of Civil Engineers

Primary Web Site: [Web Link]

Secondary Web Site: [Web Link]

Visit Instructions:
The listed coordinates for this waymark must be personally visited.

Please submit at least one ORIGINAL PHOTO of the structure, preferably one showing a different aspect, angle, season, etc. from the original waymark.

Give the DATE of your visit and any comments or additional information that will help other visitors enjoy this site.
Search for...
Geocaching.com Google Map
Google Maps
MapQuest
Bing Maps
Trails.com Maps
Nearest Waymarks
Nearest Engineering Landmarks
Nearest Geocaches
Nearest Benchmarks
Nearest Hotels
Create a scavenger hunt using this waymark as the center point
Recent Visits/Logs:
Date Logged Log User Rating  
stevepre2 visited Smithfield Street Bridge - Pittsburgh, PA 7/22/2017 stevepre2 visited it
Sharon12 visited Smithfield Street Bridge - Pittsburgh, PA 7/1/2016 Sharon12 visited it
stinger503 visited Smithfield Street Bridge - Pittsburgh, PA 6/25/2012 stinger503 visited it
Andy961 visited Smithfield Street Bridge - Pittsburgh, PA 5/27/2012 Andy961 visited it
marysuewashere visited Smithfield Street Bridge - Pittsburgh, PA 8/22/2010 marysuewashere visited it
Metro2 visited Smithfield Street Bridge - Pittsburgh, PA 9/13/2009 Metro2 visited it
NorStar visited Smithfield Street Bridge - Pittsburgh, PA 5/30/2009 NorStar visited it
ArmyFamily4 visited Smithfield Street Bridge - Pittsburgh, PA 4/1/2009 ArmyFamily4 visited it
onfire4jesus visited Smithfield Street Bridge - Pittsburgh, PA 3/31/2008 onfire4jesus visited it

View all visits/logs