Ponte Maria Pia cross the river Douro located in the city of Porto in Portugal. The bridge was opened in 1877 by the king of Portugal and is named for Queen Maria Pia, who lived from 1847 to 1911.
Gustave Alexandre Eiffel given the task of constructing the bridge. He is best known for the Eiffel Tower, but was also a skilled bridge engineer.
Construction of the bridge began in 1876. He used a new technique that made the bridge was faster finished.
Construction began on building the arch from each side without support from below. So building a tower on each side the river that was used to support the arch. It was attached temporary wires in the mountains, who went through the tower arch. As the arc grew was set up several wires that held the bow up. When the arch was finished it stood by itself, and the wires were removed. This technique is used today in many bridges.
While the arch was larger, was the bridge deck built out from each side.
This technique is used when he built the Eiffel Garabit Viadukt.
Maria Pia bridge has been used as a railroad bridge until 1991 when St John took over the bridge.