The Hot Metal Bridge is a 321 foot truss bridge that crosses the Monongahela River from Hot Metal Street on Pittsburgh's South Side to a ramp at Second Avenue near the Pittsburgh Technology Center. The bridge consists of two parallel spans on a single set of piers. One is the Monongahela Connecting Railroad Bridge, built in 1887, and the other the Hot Metal Bridge, built in 1900. Although they are two completely seperate spans, they commonly go by one name, the Hot Metal Bridge.

The Monongahela Connecting Railroad Bridge (upstream) carried conventional railroad traffic, while the Hot Metal Bridge (slightly elevated and downstream) connected parts of the J&L Steel mill, carrying crucibles of molten steel from the blast furnaces to the rolling mills on the opposite bank. The upstream span was converted to vehicular use in 2000, and the downstream span for pedestrian/bicycle traffic in late 2007.

The origins of the Hot Metal Bridge dates back to 1843, when a canal line manager named Benjamin Franklin Jones came to Pittsburgh. 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, located on the south bank of the Monongahela River in Birmingham (the Southside). Pittsburgh banker James Laughlin became a junior partner in 1854.

The Jones and Laughlin Steel complex on Pittsburgh's Southside was once one of the nation's largest.

The iron-making operation soon expanded to both sides of the river, with the American Steel and Iron Works, Keystone Rolling Mill and the Soho Department on the north shore, and the Jones and Laughlin Iron Works on the south shore. In 1860, the Eliza furnaces were erected on the north shore.

The Monongahela Connecting Railroad Bridge under construction in 1877.

In 1887, a railroad bridge was constructed to link the the two sides of the operation. The bridge carried two tracks for the Monongahela Connecting Railroad. In 1900, as mill operations continued to grow at a rapid pace, a second span was erected on the downstream side.

After widening the original piers, this twin-span was slightly elevated and carried a single track used to shuttle hot metal from the furnaces to the rolling mills. The floor of this side of the bridge was lined with metal plates to protect river traffic and the wooden railroad ties from the molten metal and sparks spewing from the opening at the top of each ladle railroad car. This connection made it possible to send molten metal directly from the furnaces to the mills.

The Monongahela Connecting Railroad Bridge and the Hot Metal Bridge,
part of the sprawling J&L Steel complex.

Jones and Laughlin Steel continued to expand and thrive until it's peak during World War II. The company was taken over by LTV Steel in 1974, during a downturn in the Pittsburgh-area steel industry. By 1984 the entire former-J&L complex was closed.

After several years of planning, the 130 acres of the South Side Works on the southern shore, and the forty acres on the northern shore where the Eliza furnaces once stood were completely cleared for new development, which continues to this day.

The 170 acres of the Jones and Laughlin Steel complex. By 1984 it was closed and abandoned. The old buildings
were razed and the land now occupied by a residential, office, retail and technology complex.

Overlooked for many years and nearly hidden by the sprawling industries they served, the pair of near-twin bridges, the Monongahela Connecting Bridge and the Hot Metal Bridge, have emerged after two decades of standing idle with a new purpose.

Although nearly every trace of the massive steel mills that lined each bank of the Monongahela River have vanished, the complex has been replaced by modern retail, office and apartment development on the southern shore, and a Technology Center on the northern shore. An automobile and pedestrian bridge to connect the two shores became a necessity.

The renovated Hot Metal Bridge has become a popular crossing point for motorists.

The rebirth of the Mon Con bridge was first. A $12 million renovation converted it into a two-lane bridge for motor vehicles. The bridge was opened to traffic on June 23, 2000, and provides a convenient connection between the streets of Birmingham and South Oakland. It has become a popular crossing point for motorists.

  
The Monongahela Connecting Bridge after renovation in 2001 (left) and the twin-spans a decade later in 2011.

The downstream side of the structure, the Hot Metal Bridge, was then renovated for bicycle and pedestrian use. Following $10 million in renovations, the bike/pedestrian bridge was officially opened on November 27, 2007.

A new through truss was installed to cross Second Avenue and compete the connection to the Eliza Furnace Bike Trail. On June 12, 2008, the Pittsburgh History and Landmarks Foundation installed decorative lighting on the bridge, using energy-efficient light-emitting diode (LED) and optical fiber technology.

The twin spans of the Hot Metal Bridge transport autombile, pedestrian and bicycle traffic over the Monongahela River.