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picture of bridge

View southwest from Second Ave

picture of bridge

Elevation drawing looking downstream

More detail photos

Monongahela Connecting Railroad Bridge and Hot Metal Bridge

MC RR Bridge, Mon Con Bridge


USGS 7.5" Topo Quad - UTM Coordinates:
Pittsburgh East - Zone 17; 0588 4475
Mon Con: motor vehicles, 2 lanes; Hot Metal St aka South 29th St
Hot Metal: converted for pedestrian and bicycles

-- Second Av on right descending bank of Monongahela River [former location of Jones and Laughlin Steel Eliza Furnace]
-- East Carson St at South 29th St on left descending bank of Monongahela River [former location of American Iron Works, later LTV South SIde Works]

-- Monongahela River at mile 3.1
Two sets of trusses on shared piers. Mon Con Bridge is upstream side.


TOTAL LENGTH (including longest elevated ramp):
1174'-1" (before alteration including removal of northernmost skew span)

48.4 ft, vertical clearance, channel span
Emsworth Dam normal pool level 710 ft

William Glyde Wilkins ?
Many alterations
Mon Con Bridge reopened to motor vehicles: 2000
Hot Metal Bridge reopened to bicycles and pedestrians: 2007
Overlooked for many years and nearly hidden by the industries they served, this pair of near-twin bridges built on a shared set of piers have emerged with a new life. Nearly every trace of the massive steel mills that lined each bank of the Monongahela River has vanished. All that remains is the bridge twins.

Benjamin Franklin Jones came to Pittsburgh in 1843. He worked for a private canal line, became the manager and in 1847 a partner in the company. Seeing the emerging importance of iron, Jones sold his interest in the canal business to invest in iron making. By 1850, he had formed American Iron Works which was located on the south bank of the Monongahela River at Birmingham. Pittsburgh banker, James Laughlin, purchased a large portion of the business and became junior partner in 1854.

The operation quickly expanded to both sides of the river, including the American Steel and Iron Works, Keystone Rolling Mill, the Soho Department (all on the north shore) and the Jones and Laughlin Pattern Works (lumber) accompanying the iron works on the south shore. In 1860, the Eliza furnaces were erected on the north shore. Over the years, J&L Steel expanded further, ultimately running out of room to grow and opening another location in Aliquippa.

In 1887, a railroad bridge was constructed to link the the two sides of the operation. The upstream side carried two tracks for the Monongahela Connecting Railroad. The downstream side carried a single track used to shuttle hot metal from the furnaces to the rolling mills. Previous to this direct connection, the metal had to be reheated before being worked.

William Glyde Wilkins is listed as the engineer of the foundations for the Eliza furnaces and engineer of the Monongahela Connecting Railroad while in private practice from July, 1887, to January, 1889. He was responsible for many other bridge, railroad, and industrial engineering projects. This would indicate he was likely the designer of this bridge. The 1904 Hopkins map labels the bridge as "East End Bridge Co."

There is evidence that this pair of bridges was built in several phases, then upgraded many times during its life. This has led to some confusion regarding the date of construction. The river piers show masonry joints which seem to indicate that the piers were widened to accomodate the second set of trusses. White and von Bernewitz report that the first crossing was built in 1887, but also state that the Hot Metal Bridge was built by the Edgemore Boiler Works in 1900. There are also plans in a history of J&L Steel which show modifications in 1915.

Jones and Laughlin Steel continued to expand and thrive until its peak during World War II. The history and eventual decline of Pittsburgh's steel industry is not covered here. The purchase of J&L by LTV didn't slow the eventual closure. When it was all over, 130 acres of the South Side Works and 40 acres where the Eliza furnaces once stood (Pittsburgh Technology Center) were completely cleared for new development. Only a South Side powerplant and the bridges remained.

Information about Brownfields redevelopment (CMU Brownfields Case Studies):
Pittsburgh Technology Center (north side of Mon River) [pdf]
South Side Works [pdf]

The rebirth of the Mon Con bridge was first. A $12 million renovation and conversion to a two-lane bridge for motor vehicles was completed and the bridge opened to traffic, June 23, 2000. It provides a more convenient connection between the streets of Birmingham and South Oakland. The Birmingham Bridge, less than a mile downstream, offers no easy connection from the Parkway to the South Side, and the streets leading below it to Second Avenue are somewhat difficult to follow. This new Mon Con bridge offers a much easier and logical choice due to its proximity to the Bates Street interchange of the Parkway and Second Avenue. The proposed Mon-Fayette Expressway ramps are expected to fall within 1/4 mile of the Mon Con bridge. It seems this bridge will be quickly overwhelmed by its popularity.

The downstream side of the structure, the Hot Metal Bridge, is scheduled to be renovated for bicycle and pedestrian use. The northernmost truss and elevated section were removed to allow the construction of a simple ramp angling down to meet Second Avenue. Following $10 million in rennovations, the bike/pedestrian bridge was officially reopened, November 27, 2007. A new through truss was installed to cross Second Avenue and compete the connection to the Eliza Furnace Trail ("Jail Trail"). On the south end, the Mon Con bridge was also at such a level that a simple ramp allows access for motor vehicles. The Hot Metal bridge, however, once ascended into the South Side Works, and until the new bike ramps were completed the end of the structure hung high in the air. An example of another bridge which required this type of new connector is found in the former Herr's Island railroad bridge at the URA's Washington's Landing.

Because the bridges share piers and have similar truss designs, the pair are usually referred to simply as The Hot Metal Bridge. It is more accurate to give this name only to the downstream side. The floor of this side has metal plates lining the floor -- protecting the river traffic and the wooden ties from the molten metal and sparks spewing from the opening in the top of each ladle railroad car. Similar cars may still be seen at the USX Edgar Thompson Works in Braddock; remote-controlled trains pass near the Braddock Lock and Dam No. 2 on the Mononghela River.

This is also not Pittsburgh's only Hot Metal Bridge. Another spans the Monongahela River at Mile 8.6 to join the derelict remains of the Carrie Furnaces at Rankin with the big-box suburban development that has replaced the Homestead Steel Works.

Historic American Engineering Record documents:

view page - Monongahela Connecting Railroad, Main Bridge (HAER PA-277-B); Richard L. McCombs, Monongahela Connecting Railroad Company

view page - Monongahela Connecting Railroad, J&L Steel Hot Metal Bridge (HAER PA-277-C); Richard L. McCombs, Monongahela Connecting Railroad Company


USACE Monongahela River Nav. Charts; cited websites; HAER

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Introduction -- Nearby Structures

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Last modified: 25-Jul-2001

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