Smithfield Street Bridge
40.434081 - 80.002668Koordinaten: 40 ° 26 ' 2.7 "N, 80 ° 0' 9.6 " W
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The Smithfield Street Bridge is the oldest of the numerous road bridges over the Monongahela River in Pittsburgh, Pennsylvania, USA. After the Eads Bridge in St. Louis, Missouri is one of the oldest steel bridges in the United States and its first lens support bridge. You and the Royal Albert Bridge, opened in 1859 in Plymouth, England, are probably the most important of the surviving original lens girder bridges.
Location
The bridge is located in the extension of Smithfield Street and connects the city center with the southern river bank below the Mt Washington. It is the penultimate bridge (before the Fort Pitt Bridge ) over the Monongahela River before its confluence with the Allegheny River to the Ohio River.
Description
Built by Gustav Lindenthal in the years 1881 to 1883 Smithfield Street Bridge consists of two main openings, the bridge deck is supported by three parallel, arranged above lenticular Pauli carriers. On both sides make steel trestle bridges, each with two ports to connect to the shore. To the north, in the direction of the city center, stands between the bank and the first buildings a modern building of road under-and overpasses, with the Penn Lincoln Parkway and a carriageway of the Fort Pitt Boulevard to cross and which is no longer counted in the Smithfield Street Bridge. In the south, two openings of the initial ramp bridge was replaced by a steel arch bridge that crosses today two of the previous four railway tracks.
The bridge is including the bridge over the tracks of a total of 361 m ( 1184 ft ) long. The two main openings among the lens wearers have spans of 110 m (360 ft).
About the eastern half of the bridge carries one lane in the city center, on the other half there are two lanes southbound. The bridge was the last major overhaul back the original colors of blue for the lens carrier, yellow for the portals and Brown for the track support.
History
Covered bridge (1818-1845)
At the point of the Smithfield Street Bridge in 1818 was Pittsburgh's first river bridge, the Monongahela Bridge, which replaced the ferries used hitherto. The then famous Bridge engineer Wernwag Lewis (1769-1843) was in the course of a year to build a covered wooden bridge over the channeled not through seawalls river. The distance between the abutments on the slopes was 457 m (1500 ft ) therefore longer than the bridge today. 7 brick piers in center distances of each 57.3 m (188 ft) supported the eight executed in the Burr Truss construction phases of construction. The bridge had two lanes for heavy wagons. Your northern end consisted of a brick portal building with two passages through which the flat of Mauteinnehmers was.
1832 rammed a loss of control of ship a pillar and thereby brought two spans to collapse. After extensive repairs she continued to provide good services until it was destroyed on 10 April 1845 Great Fire of Pittsburgh. Only the piers in the river stopped.
Suspension bridge (1846-1883)
John A. Roebling was working at the time of the completion of his first suspension bridge, which has become known as Allegheny Aqueduct Canal Bridge across the Allegheny River. He was commissioned immediately after the Great Fire, to build on the still existing brick pillars a new bridge - his first suspension bridge for road traffic. Work began in June 1845 with extensive repairs to the piers and abutments. In this two stone blocks were built from brick, which served as foundations for the cast iron pylons. The suspension ropes were attached to the tops of the pylons on moving pendulum -makers, so that through the bridge moving loads of carts exerted no lateral, but only vertical loads on the pylons. The floor beams of wooden truss structures were thus supported on both sides by a total of 18 support cables. He used produced wires that were pressed together with the further developed by him air spinning process to parallel wire cables for preparing the suspension cable in his factory. Roebling connected even then the support cables with a combination of trailers and stay cables to achieve the highest possible stiffness of the track support. Just as the old bridge and the new suspension bridge 457 m (1500 ft ) long and had eight spans each 57.3 m span. Their track was 6.10 m (20 ft) wide. Outside of the ropes there were two 1.5 m (5 ft) wide sidewalks; the bridge was a total of 9.75 m (32 ft) wide.
The bridge was completed in February 1846. She served for 35 years, especially the heavy four - and sechspännigen, later also achtspännigen carts that brought coal to the city and heavy iron parts and equipment carried. As the traffic increased and the loads were larger, they finally did show significant distortions. 1871 saw the first proposals to build a new bridge, but it took another ten years until the order is placed.
Lens wearers Bridge ( 1883)
1881 Gustav Lindenthal was asked to design a new Smithfield Street Bridge, which was completed in 1883. The two lanes were equally used by the tram and the carts; the sidewalks were attached externally to the bridge. The bridge was 14.6 m (48 ft) wide, but left open the possibility to extend it later to 19.5 m (64 ft). It was therefore built on masonry piers that jutted out at the inflow side of the bridge. The walkway on this page can be removed for expansion.
The main openings were bridged with two each 110 m long Pauli carriers, which framed the 7 m wide two-lane roadway. The two 3 m wide walkways were outside the carrier. The Pauli carriers were largely built of steel, which made a significant saving compared to the wrought iron used until then. Your upper chord consists of riveted double T -beams, the bottom chord of several parallel rods eyes. Intricate carrier with truss bars are the vertical and horizontal braces, diagonal bracing of each 13 subjects in turn consist of very long and adjustable bars eyes. The Pauli carrier store on steel supports that are on the piers. The steel columns were hidden inside of cast iron portals according to the time. The two outer portals also had a single serving of ornament essay.
The two abutments were significantly closer to the middle of the river than the previous bridges in the area of the embankments. They were connected by iron girder bridges with main spans. Had the Smithfield Street Bridge at that time spans ( from north to south ) of 12 25 26 110 110 27 26 19 17 m; overall the building was thus 372 m long.
The bridge was built over the old bridge, while traffic continued to run on this. The bridge company had originally intended, the new bridge 15 ft higher than let the old building, while the representatives of shipping an increase of 20 ft on a clear height above the low water of at least 57 ft ( 17.4 m ) called. This eventually led to legal wrangling and a 10-month construction freeze. To avoid even longer interruptions, the bridge company eventually agreed to increase by 20 ft.
In the years 1890-1891 the bridge of Lindenthal was, as intended from the outset to extend a roadway. The bridge received for a third row of Pauli carriers and additional boxes next to the existing steel girder bridges. The two cast-iron portals were also doubled. The tram tracks were laid in the middle of the bridge on both sides of the central support.
1896 purchased by the city administration, the bridge, which could later be used toll-free.
1911 shifted to the new carrier by about 1.5 m outwards and moved both tram tracks on this part of the bridge so that the overall traffic on the old site was now separated from the trams. In the following years the elaborate portals have been replaced by the current, much simpler portals made of cast steel.
1933-1934 the floor beams were overhauled and provided with a bridge deck made of aluminum, which reduced the weight of the bridge by 675 tons. This measure was at the time the largest aluminum project in bridge construction.
1966 to 1967 there was again extensive renovation work on the bridge deck, which reduced the weight by a further 97 tons. In 1985, the operation of the tram has been set, the tracks were removed in 1994 in a major overhaul. The bridge was again the colors of the original bridge.
Awards
The Smithfield Street Bridge was documented including in the Historic American Engineering Record ( HAER ), established in 1975 by the American Society of Civil Engineers as a National Historic Civil Engineering Landmarks in the list of historical milestones in the civil engineering and declared 1980 a National Historic Landmark.