The Three Sisters
Through Sixth Street's suspender and main cable eyebars, Seventh and Ninth Street Bridges can be seen | | Official name | {{{official_name}}} | | Carries | 2 Vehicular lanes, 2 sidewalks | | Crosses | Allegheny River | | Locale | Pittsburgh, Pennsylvania | | Maintained by | Allegheny County | | ID number | {{{id}}} | | Design | Self-anchored suspension bridges | | Longest span | {{{mainspan}}} | | Total length | {{{length}}} | | Width | {{{width}}} | | Vertical clearance | {{{clearance}}} | | Clearance below | {{{below}}} | | Average Daily Traffic | {{{traffic}}} | | Opening date | {{{open}}} | | Destruction date | {{{closed}}} | {{{map_cue}}}
{{{map_text}}} | [[Image:{{{map_image}}}|{{{map_width}}}| ]] | | | The Three Sisters are three very similar Self-anchored suspension bridges spanning the Allegheny River in Pittsburgh, Pennsylvania, USA. Designed by the Allegheny County Department of Public Works, they were all built in a four year period, from 1924 to 1928, by the American Bridge Company, replacing earlier bridges of various designs at the same sites. Their construction was mandated by the War Department, citing navigable river clearance concerns. They are constructed of steel, and use steel eyebars in lieu of cables. They span the Allegheny at 6th, 7th, and 9th streets in downtown Pittsburgh, running generally north/south. Image File history File links Download high resolution version (1024x735, 172 KB) Summary Jet Lowe, photographer, summer 1999. ...
The Allegheny River (historically, especially in New York state, also spelled Allegany River) is a principal tributary of the Ohio River, which it forms with the Monongahela River at the downtown Pittsburghs Golden Triangle point. The river is approximately 325 mi (523 km) long, in the U.S. states...
City nickname: The Steel City Location in the state of Pennsylvania Founded 1758 Mayor Tom Murphy (Dem) Area - Total - Water 151. ...
Official language(s) None Capital Harrisburg Largest city Philadelphia Area - Total - Width - Length - % water - Latitude - Longitude Ranked 33rd 119,283 km² 255 km 455 km 2. ...
Allegheny County is a county located in the U.S. state of Pennsylvania. ...
The National Bridge Inventory (NBI) is a database, compiled by the Federal Highway Administration, with information on all bridges and tunnels in the United States that have roads passing above or below. ...
Proposed self-anchored suspension span A self-anchored suspension bridge is a type of bridge combining elements of a suspended-deck suspension bridge and a cable stayed bridge. ...
Proposed self-anchored suspension span A self-anchored suspension bridge is a type of bridge combining elements of a suspended-deck suspension bridge and a cable stayed bridge. ...
The Allegheny River (historically, especially in New York state, also spelled Allegany River) is a principal tributary of the Ohio River, which it forms with the Monongahela River at the downtown Pittsburghs Golden Triangle point. The river is approximately 325 mi (523 km) long, in the U.S. states...
City nickname: The Steel City Location in the state of Pennsylvania Founded 1758 Mayor Tom Murphy (Dem) Area - Total - Water 151. ...
Location in the state of Pennsylvania Formed January 22, 1800 Seat Pittsburgh Area - Total - Water 1,929 km² (745 mi²) 38 km² (15 mi²) 1. ...
The American Bridge Company is a privately held civil engineering firm specializing in the construction and renovation of bridges and other large civil engineering projects, founded in 1900, and headquartered in Coraopolis, Pennsylvania. ...
War Department may refer to the military establishments of several different countries: British War Department Confederate War Department United States Department of War, under the leadership of the United States Secretary of War (until 1947) See also: defense minister This is a disambiguation page — a navigational aid which lists other...
In this light truss bridge each side truss has sixteen elements. ...
Historical Significance They are historically significant because they are the only trio of nearly identical bridges, as well as the first self-anchored suspension spans, built in the United States. They are among the only surviving examples of large eye- bar chain suspension bridges in America, and furthermore, unusual for having been erected using cantilever methods. The bridges’ design was viewed as a creative response to the political, commercial, and aesthetic concerns of Pittsburgh in the 1920s.
The case for Suspension Bridges Like New York City residents, Pittsburghians are quite enamoured with suspension bridges in general and some of the country's earliest and finest examples can be found in the southwestern Pennslyvania area. From 1926 through 1931, four suspension bridges were constructed across the Allegheny and Monongahela Rivers. The fourth bridge (not covered in this article) is a wire cable bridge carrying South Tenth Street across the Monongahela. A suspension bridge is a type of bridge that has been made since ancient times. ...
The “Three Sisters Bridges” represent an adaptive engineering design response to political and technical concerns. County engineers successfully maneuvered around federally-mandated clearances, aesthetic and financial considerations raised by local aqencies and the lack of adequate anchorage points along the river banks. The structures are the only trio of neariy identical bridges and among the few surviving examples of large eyebar suspension bridges in the United States. They were the first self-anchored suspension bridges built in this counrty. The design’s deck- stiffening girder provided compressive support while lowering visual barriers between Pittsburgh and the historically distinct North side (formerly Allegheny City), annexed in 1907 in a contentious fight.
It may or may not be a coincidence that American Bridge Company the builder and steel supplier for these three bridges, is headquartered nearby. as was the Foundation Company which had the pier/abutment masonry contract. Local election campaigns during the period highlighted the intent to use local suppliers and labour. The American Bridge Company is a privately held civil engineering firm specializing in the construction and renovation of bridges and other large civil engineering projects, founded in 1900, and headquartered in Coraopolis, Pennsylvania. ...
Engineering Background
 Image File history File links Download high resolution version (1320x320, 10 KB) // Summary Erection Sequence and Force Diagram, Three Sisters Bridges, from HAER. Reduced from original TIF file found here [1] and then edited to remove non erection sequence/force diagram material, rearrange some text and convert to . ...
This material OCRed from HAER
Image:Haer PBG erection force Diagram s.png, which is in the public domain, a portion of this diagram is shown above. OCR can mean: Optical character recognition. ...
Image File history File links Download high resolution version (1803x1230, 47 KB) Summary Erection Sequence and Force Diagram, Three Sisters Bridges, from HAER. Reduced from original TIF file found here: [1] Licensing Drawing 2 of 8, Reuse or reproduction requests credit to original draftsmen, to wit: Delineated by Julie A...
A suspension bridge works by hanging a roadway from cabless or chains under tension. Though a few unstiffened suspension bridges exist, a longitudinal stiffening truss or girder is usually added to prevent excessive movement of the deck. The cables pass over towers and are anchored at both ends. Conventional suspension bridges use massive concrete or rock anchorages to resist the cable’s tension. In self-anchored suspension bridges, however, the cables are fastened to both ends of the longitudinal girders. These girders are therefore compression struts in addition to stiffening the roadway.
Because each of Pittsburgh’s Three Sisters appears to be a seif-contained unit not dependent on the river banks for anchorage, a debate ensued among engineers whether these structures wre cantilevers rather than suspension kridges. While current wisdom holds them to be the latter, the erection procedure shows how each bridge was built in halves toward the center. Temporary diagonal struts between chain and deck provided shear resistance turning each incomplete half into a trussed cantilever arm. These struts ‘freed themselves’ when the halves were jacked together and connected to form a suspension bridge.
Sixth Street Bridge
From north bank of the Allegheny, downtown Pittsburgh in background | | Official name | Roberto Clemente Bridge | | Carries | Sixth Street | | Crosses | {{{crosses}}} | | Locale | {{{locale}}} | | Maintained by | {{{maint}}} | | ID number | {{{id}}} | | Design | {{{design}}} | | Longest span | 430 ft (134.7 m) | | Total length | 884 ft spans (269.4 m) (main and 2 215 side spans) 995 ft with approaches | | Width | 38 ft roadway (formerly 2 vehicle, 2 tramway tracks, now 2 wide vehicle lanes) 10ft sidewalks (outside the plate girder) | | Vertical clearance | above 78ft towers | | Clearance below | deck is 40 ft above Emsworth Dam normal pool level (710 ft above sea level) | | Average Daily Traffic | | | Opening date | October 19, 1928 | | Destruction date | {{{closed}}} | {{{map_cue}}}
{{{map_text}}} | [[Image:{{{map_image}}}|{{{map_width}}}| ]] | | | Image File history File links Download high resolution version (1024x733, 99 KB) Summary HAER PA,2-PITBU,78A-1 SIXTH STREET BRIDGE, VIEW SW BY 190 DEGREES, WITH DOWNTOWN PITTSBURGH IN BACKGROUND. Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to...
The Allegheny River (historically, especially in New York state, also spelled Allegany River) is a principal tributary of the Ohio River, which it forms with the Monongahela River at the downtown Pittsburghs Golden Triangle point. The river is approximately 325 mi (523 km) long, in the U.S. states...
City nickname: The Steel City Location in the state of Pennsylvania Founded 1758 Mayor Tom Murphy (Dem) Area - Total - Water 151. ...
Roberto Clemente Walker (August 18, 1934 – December 31, 1972) was a Major League Baseball right fielder and right-handed batter. ...
The National Bridge Inventory (NBI) is a database, compiled by the Federal Highway Administration, with information on all bridges and tunnels in the United States that have roads passing above or below. ...
October 19 is the 292nd day of the year (293rd in leap years) in the Gregorian Calendar. ...
1928 (MCMXXVIII) was a leap year starting on Sunday (link will take you to calendar). ...
Political Background Note that a large driving force for these bridges all being done at once was that the predecessor bridges were all not in compliance with War department restrictions on bridges crossing navigable waters (of which the Allegheny and Monongahela, not to mention the Ohio, included)... these restrictions governed minimum span widths over channels and minimum clearances (page 19 of the Haer record [1]
The previous bridges were all owned by private companies, established to build bridges and pay them off via tolls collected. Some controversy ensued around whether public entities could take bridges or bridge rights of way away from private companies if the companies had retired their construction loans (several of the companies in the area were paying 15% dividends yearly to stock holders as the bridges were quite profitable, even with tolls at 1 cent per man and free for women)
At some point, the public supported a "free bridges" movement that supported government buying out the bridge companies and abolishing tolls. Between that and the War department ruling that government owned bridges would not need to be corrected as quickly, the bridge companies were willing to sell and did so before 1910. The County (rather than City or State) eventually ended up as owners, buying the companies out at fair market value.
But of course, now government had to deal with the problem of non compliance when the war department raised it again at the end of the 1910 decade. Through the teens and early 20s bond issues were floated before the voters to finance replacement but were repeatedly voted down. The HAER source describes the attitude of voters as seeing public works as a source of corruption, especially at the county level.
In 1924, voters finally approved a 29.2M bond issue at hte county level to improve bridges and munincipal structures. Several proposals were floated for lift bridges of various sorts, including a scheme to raise the existing bridge on mechanical jacks, but the War Department did not approve, insisting on a failure proof means of clearance. The Seventh Street Bridge was razed in 1924, and the War Department forced the razing of the 9th as well, despite the inconvenience to the city.
After much design work, two truss bridges at 6th and 9th and a cantilever bridge at 7th were approved, and submitted to the Metropolitan Art Commission, a forgotten body that had approval rights for any bridge over 25,000 USD in the City of Pittsburgh. Expecting a rubber stamp, contracts were let, but to everyone's shock, the commission vetoed the designs as unaesthetic, preferring suspension bridges. But shoreline clearances were tight and two of the older suspension bridges had experienced problems with anchorages shifting due to inability to secure them. It is not clear who exactly suggested the self anchoring suspension bridge design finally chosen, the only precedent known at that time was a 1915 bridge over the Rhine at Cologne the Deutzer Hängebrücke. The Deutzer Hängebrücke, possibly also known as the Hindenburgbrücke was a Self-anchored suspension bridge using eyebar chains, across the Rhine in Cologne, Germany. ...
Howevr, by 1922 one of the better known advisors on cantilever and suspension bridge structures noted the peculiar strengths represented in the Cologne bridge’s design. David B. Steinman’s running dispute with J. A. L. Waddell about the relative costs of suspension and cantilever bridges continued a debate with roots in the Quebec Bridge collapse. The 1907 construction disaster, accompanied by the 1916 accident during a second attempt, heightened a growing preference for suspension bridges. In light of the popular and engineering support for suspension structures, Steinman’s first edition of A Practical Treatise on Suspension Bridges fed a growing demand for technical information about components such as eye-bars and stiffening systems. Steinman’s notoriety and the fact that his book was reviewed in the engineering press make it likely that Allegheny County’s engineers could have examined the first edition of this book. David Bernard Steinman (June 11, 1886 - August 21, 1960) was an American engineer He was the designer of the Mackinac Bridge and many other notable bridges, and a published author. ...
John Alexander Low Waddell (1854–1938, often shortened to J.A.L. Waddell) was an engineer and prolific bridge designer, with more than a thousand structures to his credit in the U.S., Canada, and other countries around the world. ...
The Quebec bridge, with the Pierre-Laporte bridge in the background. ...
Construction History The bridges had common designers and constructors since the desire was for a common look. Designers: - Allegheny Department of Public Works:
- T. J. Wilkerson, consulting engineer;
- Vernon R. Covell, chief engineer;
- A. D. Nutter, design engineer;
- Stanley L. Roush, architect.
Builders: Present Owner: Allegheny County. The American Bridge Company is a privately held civil engineering firm specializing in the construction and renovation of bridges and other large civil engineering projects, founded in 1900, and headquartered in Coraopolis, Pennsylvania. ...
Ambridge may refer to: Ambridge, a fictional place in the United Kingdom radio programme, The Archers. ...
Present Use: Vehicular bridges.
Identifying the Sisters
These bridges were originally known by their connecting street names, and informally still are. However they have been given formal names to honor local natives as follows, in order of opening:
Andy Warhol, photographed by Helmut Newton Andy Warhol (August 6, 1928 – February 22, 1987) was an American painter, filmmaker, publisher, and a major figure in the Pop Art movement. ...
Carsons Government Photo (1940s) Rachel Louise Carson (May 27, 1907 – April 14, 1964) was a Pittsburgh, Pennsylvania-born zoologist and biologist whose landmark book, Silent Spring, is often credited with having launched the global environmental movement. ...
Roberto Clemente Walker (August 18, 1934 – December 31, 1972) was a Major League Baseball right fielder and right-handed batter. ...
Sixth Street trivia The Sixth Street Bridge is at the site of Pittsburgh‘s first Allegheny River bridge,
Lothrops 1819-20 wooden covered St. Clair Bridge OFFICIAL NAME: Allegheny River Bridge
OTHER DESIGNATION: Sixth Street Bridge, St. Clair Street Bridge
LOCATION: Pittsburgh
USGS 7.5" Topo Quad - UTM Coordinates: Pittsburgh West - Zone 17; 0584 4477 CARRIED: pedestrians and horse-drawn vehicles
BETWEEN: -- Federal St [Franklin Rd] on right descending bank of Allegheny River -- Sixth St [St. Clair St] on left descending bank of Allegheny River
CROSSED: -- Allegheny River at mile 0.5 TYPE OF CONSTRUCTION / DESIGN: wooden, Burr truss, covered
LENGTH OF MAIN SPAN: four spans, 185 ft; one span, 170 ft; one span, 137 ft (HAER)
TOTAL LENGTH (including longest elevated ramp): 1,047 ft
HEIGHT OF DECK: 38 ft
YEAR ERECTED / ENGINEER: 1819, Louis Wernwag; replaced 1857 ADDITIONAL INFO: The first bridge (1819) to cross the Allegheny River and the first of four which would connect Federal St to Sixth St was a Burr arch-truss. This bridge was built as part of the project which included the first span of the Monongahela River - - the first bridge at Smithfield St -- which was completed a year earlier. Both were designed by Louis Wernwag. It was built at a cost of $92,250. (Other sources report $80,000.)
The bridge was lighted by gas lamps December 8, 1837.
Sixth St was formerly St. Clair St in Pittsburgh; it aligns with Federal St (formerly Franklin Rd which connected to the Venango Path) in the former city of Allegheny (Northside).
The first bridge to cross the Allegheny at Sixth Street was a six span, flat roofed, covered wooden bridge constructed in 1819. This bridge had a total length of 1,037 feet, consisting of four 185 foot spans, a 170 foot span, and a 137 foot span. The design and construction of this bridge have traditionally been attributed to a Mr. Lothrop; it was presumably a Burr arch truss, like the Ninth (Hand) Street Bridge, another of Lothrop's products. Physical evidence for this assumption survived until the
CORAOPOLIS BRIDGE HAER NO. PA-217 (Page 4)
1890s, when an observer reported that the skewbacks from the wooden arches remained visible in the north abutment.
Replaced by a John A. Roebling suspension bridge in 1860 OFFICIAL NAME:
OTHER DESIGNATION: Sixth Street Bridge, St. Clair Street Bridge
LOCATION: Pittsburgh
USGS 7.5" Topo Quad - UTM Coordinates: Pittsburgh West - Zone 17; 0584 4477 CARRIED: pedestrians and horse-drawn vehicles
BETWEEN: -- Federal St [Franklin Rd] on right descending bank of Allegheny River -- Sixth St [St. Clair St] on left descending bank of Allegheny River
CROSSED: -- Allegheny River at mile 0.5 TYPE OF CONSTRUCTION / DESIGN: wire rope suspension
LENGTH OF MAIN SPAN: two main spans, 344 ft; shore spans, 177 ft and 171 ft 20 ft wide roadway, two 8 ft sidewalks
TOTAL LENGTH (including longest elevated ramp): 1,036 ft
HEIGHT OF DECK:
YEAR ERECTED / ENGINEER: 1857-59, John A. Roebling; replaced 1892 ADDITIONAL INFO: Replaced the 1819 covered bridge across the Allegheny River.
Designed by John A. Roebling, who had also completed the 1845 Allegheny Aqueduct for the Pennsylvania Canal which crossed the Allegheny River near 11th St, and the 1846 suspension bridge which replaced the burned Monongahela Bridge at Smithfield St.
The elevation drawing is simplified to display on screen. Photos indicate twice as many wires and panels.
Sixth St was formerly St. Clair St in Pittsburgh; it aligns with Federal St (formerly Franklin Rd which connected to the Venango Path) in the former city of Allegheny (Northside).
n 1860 a wire-suspension bridge, designed by John A. Roebling, replaced the decaying timber structure. This bridge was four spans long, with two 344-foot main spans, and approach spans measuring 177 and 171 feet each. The bridge was dominated by cast iron towers, each formed by four cast iron columns.
Although the Roebling bridge, with its iron superstructure, was generally believed non-flammable, it fell victim to fire on June 19, 1881. The bridge was not destroyed, but its floor system of white pine and white oak was severely damaged. John Harper, president of the Allegheny Bridge Company, which owned and operated the structure, stated that he believed the fire was the result of "sparks and perhaps flame from the stacks" of passing steamboats igniting bird nests located under the superstructure of the bridge. After heavy electric streetcars were introduced to the bridge in 1890, concern over its functional capacity grew, and in 1891 plans were begun to replace the suspension bridge with one that could better handle the steadily increasing traffic, as well as permit trolleys to cross without reducing their speed.
Bowstring Truss (this URL is hard to find: http://pghbridges.com/pittsburghW/0584-4477/sixth1892.htm)
OTHER DESIGNATION: Sixth Street Bridge, St. Clair Street Bridge
LOCATION: Pittsburgh
USGS 7.5" Topo Quad - UTM Coordinates: Pittsburgh West - Zone 17; 0584 4477 CARRIED: motor vehicles, street cars
BETWEEN: -- Federal St [Franklin Rd] on right descending bank of Allegheny River -- Sixth St [St. Clair St] on left descending bank of Allegheny River
CROSSED: -- Allegheny River at mile 0.5 TYPE OF CONSTRUCTION / DESIGN: subdivided Pratt (modified Pennsylvania/Petit) through truss
LENGTH OF MAIN SPAN: (north to south) 48.5 ft; two main spans of 439.0 ft each; 105 ft approach with two 28 ft archways 40 ft wide roadway, with two 10 ft sidewalks
TOTAL LENGTH (including longest elevated ramp): 1,032.5 ft
HEIGHT OF DECK:
YEAR ERECTED / ENGINEER: 1892, Theodore Cooper; replaced 1927 (trusses moved to Ohio River back channel between Coraopolis and Neville Island) Drake & Stratton Company, Ltd, foundations and masonry Union Bridge Company, superstructure Baird Brothers of Pittsburgh, erection ADDITIONAL INFO: Replaced the 1857 Roebling suspension bridge.
Declared a toll-free bridge 16 March 1911.
The through truss spans incorporated in the present Coraopolis Bridge were originally erected across the Allegheny River at Sixth Street in Pittsburgh, linking Pittsburgh with the main business thoroughfare of neighboring Allegheny City. This was the third of four bridges to serve that location, which is considered among Pittsburgh's most important river crossings. The growth of Pittsburgh was strongly influenced by its numerous waterways, and the successful linking of the city with its neighboring communities by means of bridges was a significant factor in the development of its metropolitan identity. Allegheny City was annexed by Pittsburgh in 1907, becoming the city's "North Side".
The 1892 Sixth Street Bridge (a pair of camelback Pratt trusses and the third bridge built in this location) had a second chance. In 1927, it was lowered from its piers, the top chords partially disassembled. The structure was floated downriver to a new location over the Ohio River back channel between Coraopolis and Neville Island to make way for the current structure. After nearly 50 years of additional service, which included weight restrictions and closings during cold weather, the old bridge was replaced by a deck girder bridge which was completed in 1995.
Sixth St was formerly St. Clair St in Pittsburgh; it aligns with Federal St (formerly Franklin Rd which connected to the Venango Path) in the former city of Allegheny (Northside).
Historic American Engineeering Record (HAER): view page - Coraopolis Bridge 1892-1927; Sixth St Bridge 1927-1986 (HAER PA-217); P.A.C. Spero & Company, 1989
http://pghbridges.com/articles/haer/coraopolis_PA217/coraopolis_HAER_PA217.htm
the bridge was rebuilt again in 1892 using a Theodore Cooper bowstring truss design to support growing railway traffic between Pittsbxurgh and adjacent competitor, Allegheny City, north of the river. The current three-span structure measures 995 feet with a main span of 430 feet.
The American Institute of Steel Construction named the Sixth Street Bridge “The Most Beautiful Steel Bridge of 1928”.
see also Coraopolis Bridge To meet Wikipedias quality standards, this article or section may require cleanup. ...
Completing the Sixth Street Bridge
Work proceeded on the new Sixth Street Bridge, with the Foundation Company called to accept last-minute revisions of piers 1 and 4 to accommodate subway construction at a later date. Bion J. Arnold’s influential transportation report called for converting street-level areas downtown to pedestrian and automobile use. He recommended building tunnels for subways to connect Pittsburgh’s central business district with selected areas, including the North Side. Although business owners and city officials hotly contested the exact route for such a system, the North Side access required by any future subway system was not in doubt.153 The revisions proposed constructing tunnel shields that could be pierced when the city decided on a final route. The tubes were 68’-O’ on center, with suggested radii ranging from 7-9” to 9’-O’, and steel reinforcement overhead. One proposal for the construction shows plans using three separate open box caissons to foiiii the base of each pier)54 The tube openings provided slightly different angles for each direction to adapt to the grades and length of approaches on north and south shores, anticipating lines that bent outward to avoid the two main piers. The city of Pittsburgh absorbed the cost of the alterations to the original plan, paying the Foundation Company the same contract costs negotiated for the bridge work of up to $40,000 for the south pier and $80,000 for the north pier.’55 (The subway openings have yet to be used, however. Pittsburgh’s underground light rail system, constructed between 1980 and 1985, follows a Sixth Street alignment for several blocks but does not cross the river.)
Even with the subway alterations, the Foundation Company completed its work four months ahead of schedule, leaving to the American Bridge Company a working schedule during Pittsburgh’s bitter winter weather. The company continued to fabricate components at its Ambridge shop, completing two-fifths of the 6,000 tons needed while it waited for better river conditions. In the meantime, workers pre-assembled smaller components off site. Brown’s office justified the apparent delay in a press release, responding to business owners who insisted that work continue amidst the winter by noting no contractor could reasonably be expected to erect the side-span falsework necessary for the project with the dangerous currents and ice faced by the American Bridge Company. The uniqueness of a suspension bridge erected by cantilever 156 methods required exceptional caution
Seventh Street Bridge Seventh Street Bridge
From north bank of the Allegheny, looking SW, downtown Pittsburgh in background, Sixth Street Bridge at right. Shows main plate girder (bearing compressive forces) and sidewalk support | | Official name | Andy Warhol Bridge | | Carries | Seventh Street | | Crosses | {{{crosses}}} | | Locale | {{{locale}}} | | Maintained by | {{{maint}}} | | ID number | {{{id}}} | | Design | {{{design}}} | | Longest span | 442 ft (xxx m) | | Total length | 884 ft spans (269.4 m) (main and 2 221 side spans) 1061 ft with approaches (xxx m) | | Width | 38 ft roadway (formerly 2 vehicle, 2 tramway tracks, now 2 wide vehicle lanes) 10ft sidewalks (outside the compressive plate girder) or total 62 ft | | Vertical clearance | above 83.5ft towers | | Clearance below | deck is 40.1 ft above Emsworth Dam normal pool level (710 ft above sea level) | | Average Daily Traffic | | | Opening date | June 17, 1926 | | Destruction date | {{{closed}}} | {{{map_cue}}}
{{{map_text}}} | [[Image:{{{map_image}}}|{{{map_width}}}| ]] | | | Image File history File links Download high resolution version (1024x732, 106 KB) Summary Jet Lowe, photographer, summer 1999 PA-490-B-1 SEVENTH STREET BRIDGE, LOOKING SW WITH SIXTH STREET BRIDGE IN BACKGROUND. Pittsburgh Seventh Street Bridge. ...
The Allegheny River (historically, especially in New York state, also spelled Allegany River) is a principal tributary of the Ohio River, which it forms with the Monongahela River at the downtown Pittsburghs Golden Triangle point. The river is approximately 325 mi (523 km) long, in the U.S. states...
City nickname: The Steel City Location in the state of Pennsylvania Founded 1758 Mayor Tom Murphy (Dem) Area - Total - Water 151. ...
Andy Warhol, photographed by Helmut Newton Andy Warhol (August 6, 1928 – February 22, 1987) was an American painter, filmmaker, publisher, and a major figure in the Pop Art movement. ...
The National Bridge Inventory (NBI) is a database, compiled by the Federal Highway Administration, with information on all bridges and tunnels in the United States that have roads passing above or below. ...
June 17 is the 168th day of the year in the Gregorian calendar (169th in leap years), with 197 days remaining. ...
1926 (MCMXXVI) was a common year starting on Friday (link will take you to calendar). ...
Seventh Street Trivia Replaced a two-span suspension bridge (1884-1925) which had truss-bracing on catenaries holding two eyebar-chain cables in concentric arcs. This previous bridge was designed by Gustav Lindenthal three years after he built the Smithfield Street Bridge. OFFICIAL NAME: Seventh Street Bridge
OTHER DESIGNATION: Irvine (Irwin) Street Bridge
LOCATION: Pittsburgh
USGS 7.5" Topo Quad - UTM Coordinates: Pittsburgh West - Zone 17; 0584 4477 CARRIED: motor vehicles
BETWEEN: -- Sandusky St on right descending bank of Allegheny River -- Seventh St [Irvine/Irwin St] on left descending bank of Allegheny River
CROSSED: -- Allegheny River at mile 0.6 TYPE OF CONSTRUCTION / DESIGN: Suspension - - catenaries were steel eyebar chain arranged in concentric pairs connected by lattice girders steel eyebar suspenders
LENGTH OF MAIN SPAN: two main spans, 320 ft; two side spans, 165 ft
TOTAL LENGTH (including longest elevated ramp): 970 ft
HEIGHT OF DECK:
YEAR ERECTED / ENGINEER: 1885, Gustav Lindenthal; replaced 1925 ADDITIONAL INFO: A two-span suspension bridge which had truss-bracing on catenaries holding two eyebar-chain cables in concentric arcs. This bridge was designed by Gustav Lindenthal three years after he built the Smithfield Street Bridge.
Declared a toll-free bridge 16 March 1911.
Seventh St was formerly Irvine St (or Irwin St) in Pittsburgh; it aligns with Sandusky St in the former city of Allegheny (Northside).
UTM coords
UTM Coordinates:
- 17/584520/4477650 (Sixth Street Bridge)
- 17/584700/4477750 (Seventh Street Bridge)
- 17/584840/4477785 (Ninth Street Bridge)
Dates of Construction: - 1926-28 (Sixth Street Bridge)
- 1924-26 (Seventh Street Bridge)
- 1924-26 (Ninth Street Bridge)
Ninth Street Bridge
From south bank of the Allegheny, looking NE, oblique view of roadway and south tower, showing eyebar links for main suspenders and roadway suspenders, as well as main compressive stiffening girders dividing roadway from sidewalks | | Official name | Rachael Carson Bridge | | Carries | Ninth Street | | Crosses | {{{crosses}}} | | Locale | {{{locale}}} | | Maintained by | {{{maint}}} | | ID number | {{{id}}} | | Design | {{{design}}} | | Longest span | 410 ft (xxx m) | | Total length | 840 ft spans (xxx m) (main and 2 215 side spans) 995 ft with approaches (xxx m) | | Width | 38 ft roadway (formerly 2 vehicle, 2 tramway tracks, now 2 wide vehicle lanes) 10ft sidewalks (outside the compressive plate girder) or total 62 ft | | Vertical clearance | above 78 ft towers | | Clearance below | deck is 40.3 ft above Emsworth Dam normal pool level (710 ft above sea level) | | Average Daily Traffic | | | Opening date | 26 November 1926 | | Destruction date | {{{closed}}} | {{{map_cue}}}
{{{map_text}}} | [[Image:{{{map_image}}}|{{{map_width}}}| ]] | | | Image File history File links Download high resolution version (1024x736, 80 KB) Summary Pittsburgh Ninth Street Bridge. ...
The Allegheny River (historically, especially in New York state, also spelled Allegany River) is a principal tributary of the Ohio River, which it forms with the Monongahela River at the downtown Pittsburghs Golden Triangle point. The river is approximately 325 mi (523 km) long, in the U.S. states...
The National Bridge Inventory (NBI) is a database, compiled by the Federal Highway Administration, with information on all bridges and tunnels in the United States that have roads passing above or below. ...
November 26 is the 330th day (331st on leap years) of the year in the Gregorian calendar. ...
1926 (MCMXXVI) was a common year starting on Friday (link will take you to calendar). ...
Ninth Street Trivia The previous bridge was a Pratt truss:
TYPE OF CONSTRUCTION / DESIGN: Pratt through truss
LENGTH OF MAIN SPAN: (north to south) five 16 ft stone arch spans viaduct; 152.5 ft side span; three 205 ft river spans; 152.5 side span
TOTAL LENGTH (including longest elevated ramp): 1,000 ft
HEIGHT OF DECK:
YEAR ERECTED / ENGINEER: 1890, Ferris and Kaufman & Company; replaced 1926 Iron City Bridge Company, contractor ADDITIONAL INFO: Designed by George Washington Gale Ferris, Jr.. and Gustave Kaufman, both graduates Rensselaer Polytechnic Institute in Troy, NY. The RPI Bulletin of March 1931 shows a photo of this bridge under construction. In the photo, the steel and wrought iron Pratt truss is being built around the older Burr arch truss stucture. George Washington Gale Ferris, Jr. ...
Ferris is most famous as the inventor of the Ferris Wheel amusement ride. Legend has it that Ferris got the inspiration for the Wheel as a boy living near the Carson River in Nevada. He saw a large undershot water wheel near the 1861 Cradlebaugh Bridge, south of Carson City, and wondered what it would be like to ride in one of its buckets. A Ferris wheel (or, more commonly in the UK, big wheel) is an amusement ride consisting of an upright wheel with passenger gondolas suspended from the rim. ...
Declared a toll-free bridge 16 March 1911.
Ninth St was formerly Hand St in Pittsburgh; it aligns with Anderson St in the former city of Allegheny (Northside).
The "Gazette Times" Feb 28, 1925 indicates this bridge was opened in 1890.
Location
External Links for all three bridges - search all 4 HAER collections using "self anchored suspension bridges" term
- report HAER "Three Sisters Bridges, Spanning Allegheny River at Sixth, Seventh & Ninth Streets, Pittsburgh, Allegheny County, PA" 43 pages. Some material in this article was adapted from this (public domain) work.
- Drawings From Historic American Engineering Record
- Pittsburgh West section of "Bridges and Tunnels of Allegheny County, Pennsylvania, from pghbridges.com
- Field Notes Details of eyebar layering, construction, dimensional notes, a very thorough survey. From pghbridges.com
- Three Sisters entry at BridgeMeister.com
- Google Map link showing all 3 bridges
External Links for Sixth Street Bridge - entry at Structurae.de
- entry at pghbridges.com
- entry at BridgeMeister.com
- August 1998 press release about renaming to Roberto Clemente Bridge
External Links for Seventh Street Bridge - entry at Structurae.de
- entry at pghbridges.com
- entry at BridgeMeister.com
External Links for Ninth Street Bridge - entry at Structurae.de
- entry at pghbridges.com
- entry at BridgeMeister.com
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