Science Fair Project Encyclopedia
Pont du Gard
Pont du Gard means literally bridge over the Gard (river). The Gard river, which has given its name to the Gard département, does not actually exist under this name. The river, formed by many tributaries, several of which are called Gardon, is itself called Gardon until its end.
Built on three levels, the Pont is 49 m high, and the longest level is 275 m long.
- Lower level: 6 arches, 142 m long, 6 m thick, 22m high
- Middle level: 11 arches, 242 m long, 4 m thick, 20 m high
- Upper level: 35 arches, 275 m long, 3 m thick, 7 m high
On its first level, it carries a road and at the top of the third level, a water conduit, which is 1.8 meters (6 feet) high and 1.2 meters (4 feet) wide and has a gradient of 0.4 percent.
The pont is thought to have been built around 19 BC. It was part of a nearly 50 km (31 mi) aqueduct, bringing water from springs near Uzès to the Roman city of Nemausus (Nîmes). The full aqueduct had a gradient of 34 cm/km (1/3000), descending only 17 m vertically in its entire length. The pont itself was built so that the water could cross the small Gardon river valley, delivering 20,000 cubic meters (44 million gallons) of water daily to Nîmes.
It was constructed entirely without the use of mortar, the stones - some of which weigh up to 6 tons - all of which are held together with iron clamps. The masonry was lifted into place by block and tackle with a massive human treadmill providing the power for the winch. A complex scaffold was erected to support the aqueduct as it was being built. The face of the aqueduct still bears the mark of its construction, in the form of protruding scaffolding supports and ridges on the piers which bore the semicircular wooden frames on which the arches were constructed. It is believed to have taken about three years to build, employing between 800-1,000 workers.
From the 4th century onwards, it began to be less maintained, and deposits filled up to two thirds of the conduit space. By the 9th century, it became unusable, and the people of the area started using its stones for their own purposes. However, the majority of the aqueduct remains remarkably intact.
From the Middle Ages to the 18th century, the Pont was used as a road bridge to cross the river. The pillars of the second level were reduced in width to make more room for the traffic, but jeopardizing the stability of the structure. In 1702 the pillars were restored to their original width. In 1743, a bridge was built next to the arches of the lower level, so that the road traffic could continue without damaging the Roman aqueduct. The bridge was restored in the 18th century, when it became a major tourist sight, and was restored again in the reign of Napoleon III in the mid-19th century.
The outstanding quality of the bridge's masonry led to it becoming an obligatory stop for French journeymen masons on their traditional tour around the country (see Compagnons du Tour de France), many of whom have left their names on the stonework. Markings left by the original builders can also be seen, indicating the positions in which the dressed stones were to be placed: for instance, FRS II (standing for frons sinistra II, or "left front 2").
In 1998 the Pont du Gard was hit by major flooding which caused widespread damage in the area. The road leading up to it and the neighboring facilities were badly damaged, although the aqueduct itself was not seriously harmed.
The French Government sponsored a major redevelopment project in conjunction with local sources, UNESCO and the EU which concluded in 2000, pedestrianising the entire area around the aqueduct and greatly improving the visitor facilities, including establishing a museum on the north bank. The project has been criticized for its cost (€32 million) and for the perceived loss of natural beauty of the surrounding landscape and area. One side-effect is that it is no longer possible to walk through the conduit at the top of the aqueduct. Nonetheless, it is still one of France's top tourist attractions, with 1.4 million visitors reported in 2001.
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