Context:
The Pont Neuf - New Bridge - is a masonry arch bridge crossing the Seine river in Paris, and spanning both sides of the île de la Cité. The construction of the bridge was between 1578 and 1607, meaning the bridge’s construction began under Henry III, who commissioned it in an attempt to gain support from the citizens, and Henry IV.
The Pont Neuf was the first bridge to cross the river Seine in a single span and one of the first masonry bridges in Europe to not have houses along its sides, but footpaths instead. This meant that the bridge itself, not only linked the right bank of Paris to the left, enabling the growth of Paris’ cultural centre with the construction of the Palais Royale and the Champs - Elysées, but also became a tourist attraction unto itself due to its pedestrian nature. In fact, the word, “pieton,” meaning , “pedestrian,” first appeared in French dictionaries in the early 17th century, demonstrating how the non-vehicle zones on either side of the Pont Neuf significantly impacted urban planning. The saying, that at any one time one could be sure to find, “a monk, a white horse and a prostitute,” on the Pont Neuf is testament to the unifying nature of the bridge, which was one of the first places in a European capital to emphasise how the different classes could be brought together through positive cohesion.
Structure and structural behaviour:
The Pont Neuf is a masonry voussoir arch bridge, whose arches were originally semi-circular. Semi-circular arch bridges are bridges in which the radius of each arch is equal to the distance from the apex to the centre point between the two piers. In these types of bridges the voussoirs which constitute the arch are put into compression due to their wedge shape, transferring the load to the piers. They were popularised by the Romans due to the facility with which the arches could be constructed. This is because each arch could be constructed individually with no additional buttressing support, so it was possible to construct long chains with relative ease, in order to form a bridge. The bridge has 5 arches between the left bank and Île de la Cité and 7 arches between the Île de lat Cité and the right bank.
Construction:
The construction of the bridge began in 1578. The wooden foundations were lain between the left bank and the Île de la Cité in the riverbed, on top of which 4 masonry piers were built. However in 1579, the design of the bridge changed from 4 arches on the left and 8 on the right, to 5 arches on the left and 7 on the right. This meant that the length of the protrusion of the platform on the island was reduced by 10 toises - 18.5 metres - and an additional pier was constructed.
The construction was then paused for 9 years due to the wars of religion but subsequently resumed. After the construction of all the piers, semi-circular wooden frames were used to place the stone voussoirs and mortar before the keystones were installed in all the arches to make them self-supporting. In 1848 - 1855, there was a large scale renovation/adaptation to lower the road and pavement level. In order to accomplish this, the arches were made elliptical, meaning the curvature of each arch was altered from semi-circular to elliptical. Following this, the bridge was not renovated again until 1994 to 2007 in time for the bridges 400 year anniversary.