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Pont du Gard (Roman Aqueduct)

UNESCO World Heritage Site
Criteria	Cultural: i, iii, iv
Reference	344
Inscription	1985 (9th Session)

The Pont du Gard is a notable ancient Roman aqueduct bridge that crosses the Gard River in southern France. It is part of a 50 km (31 mi) long aqueduct that runs between Uzès and Nîmes in the South of France. It is located in Vers-Pont-du-Gard near Remoulins, in the Gard département. The aqueduct was constructed by the Romans in the first century AD and was added to UNESCO's list of World Heritage Sites in 1985. It is the highest of all Roman aqueduct bridges and is the best preserved after the Aqueduct of Segovia. Today it is one of France's most popular tourist attractions.

Description

The Nîmes aqueduct

The Nîmes aqueduct originally carried water from a source at the Fontaine d'Eure near Ucetia (Uzès) to a delivery tank or castellum divisorum in Nemausus (Nîmes), from where it was distributed to fountains, baths and private homes around the city. Although the straight-line distance between the two is only about 20 km (12 mi), the aqueduct takes a winding route measuring around 50 km (31 mi) to avoid the Garrigue hills above Nîmes. The Garrigues are the southernmost foothills of the Massif Central. They are difficult to cross, as they are covered in dense vegetation and indented by deep valleys, and it was impractical for the Romans to attempt to tunnel through the hills. A roundabout course was therefore the only practical way of transporting the water from the spring to the city.

The Fontaine d'Eure, at 76 m (249 ft) above sea level, is only 17 m (56 ft) higher than the delivery tank or castellium in Nîmes, but this provided a sufficient gradient to sustain a steady flow of water to the 50,000 inhabitants of the city. The aqueduct's average gradient is only 1 in 3,000. It varies widely along its course, but is as little as 1 in 20,000 in some locations. The Pont du Gard itself descends 2.5 cm (0.98 in) in 456 m (1,496 ft), a gradient of 1 in 18,241. It is estimated that the aqueduct supplied the city with around 200,000,000 litres (44,000,000 imp gal) of water a day that took nearly 27 hours to flow from the source to the city.

The spring still exists and is the site of a small modern pumping station. It provides water that is pure but high in dissolved calcium carbonate leached out of the surrounding limestone. The carbonates caused significant problems for the maintenance of the aqueduct, as they precipitated out of the water during its journey through the conduit. This led to the flow of the aqueduct progressively becoming reduced by deposited carbonates. Another threat was posed by vegetation penetrating the stone lid of the channel. As well as obstructing the flow of the water, dangling roots would introduce algae and bacteria that would decompose in a process called biolithogenesis, producing concretions within the conduit. It had to be maintained continuously by circitores, maintenance workers responsible for its upkeep, who would crawl along the conduit scrubbing the walls clean and getting rid of any vegetation.

Like most Roman aqueducts, much of it was built underground. It was constructed by digging a trench in which a stone channel was built and enclosed by an arched roof of stone slabs, which was then covered with earth. Some sections of the channel are tunnelled through solid rock. In all, 35 km (22 mi) of the aqueduct was constructed below the ground. The remainder had to be carried on the surface, either on a wall or on arched bridges. Some substantial remains of the above-ground works can still be seen today, such as the so-called "Pont Rue" that stretches for hundreds of metres around Vers and still stands up to 7.5 m (25 ft) high. However, the Pont du Gard is by far the best preserved section of the entire aqueduct.

The Pont du Gard

Built on three levels, the Pont is 49 m (161 ft) high above the river at low water and 274 m (899 ft) long. Its width varies from 9 m (30 ft) at the bottom to 3 m (9.8 ft) at the top. The three levels of arches are recessed, with the main piers in line one above another. The span of the arches varies slightly, as each was constructed independently to provide flexibility to protect against subsidence. Each level has a differing number of arches:

The first level of the Pont du Gard adjoins a road bridge that was added in the 18th century. The water conduit or specus, which is about 1.8 m (5.9 ft) high and 1.2 m (3.9 ft) wide, is carried at the top of the third level. The upper levels of the bridge are slightly curved in the upstream directions, a fact long attributed to the engineers wanting to strengthen it against the flow of water, like a dam wall. However, a microtopographic survey carried out in 1989 showed that the bend is caused by the daily expansion and contraction of stones under the heat of the sun, by about 5 mm (0.20 in). Over the centuries, this process has produced the deformation witnessed now.

The Pont du Gard was constructed entirely without the use of mortar or clamps. It contains an estimated 50,400 tons of stone with a volume of some 21,000 m³; some of the individual blocks weigh up to 6 tons. They were precisely cut to fit perfectly together by friction alone, eliminating the need for mortar. The builders also left inscriptions on the stonework conveying various messages and instructions. Many blocks were numbered and inscribed with the required locations, such as fronte dextra or fronte sinistra (front right or front left), to guide the builders.

The identity of the architect is unknown, but the method of construction is fairly well understood. The patron of the aqueduct – a rich individual or the city of Nîmes itself – would have hired a large team of contractors and skilled labourers. The route would have been planned by a surveyor or mensor, using a groma for sighting, the chorobates for levelling, and a set of measuring poles five or ten Roman feet long. He would have recorded figures and perhaps drawn plans on wax tablets, later to be written up on scrolls. The builders may have used templates to guide them with tasks that required a high degree of precision, such as carving the standardised blocks from which the water conduit was constructed.

The builders would have made extensive use of cranes and block and tackle pulleys to lift the stones into place. Much of the work could have been done using simple sheers operated by a windlass. For the largest blocks, a massive human-powered treadmill would have been used; such machines were still being used in the quarries of Provence until as late as the start of the 20th century. A complex scaffold was erected to support the bridge as it was being built. Large blocks were left protruding from the bridge to support the frames and scaffolds used during construction. The stone came from local quarries. The aqueduct as a whole would have been a very expensive undertaking; Émile Espérandieu estimated the cost to be over 30 million sesterces.

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• Pont du Gard stonework.jpg Pont du Gard stonework.jpg
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Although the exterior of the Pont du Gard is rough and relatively unfinished, the builders took care to ensure that the interior of the water conduit was as smooth as possible so that the flow of water would not be obstructed. The walls of the conduit were constructed from dressed masonry and the floor from concrete. Both were covered with a stucco incorporating minute shards of pottery and tile. It was painted with olive oil and covered with maltha, a mixture of slaked lime, pork grease and the viscous juice of unripe figs. This produced a surface that was both smooth and durable.

The Pont du Gard's design represents a fairly early stage in the development of Roman aqueducts. Its designer's technique of stacking arches on top of each other is clumsy and expensive, as it necessitates the use of a very large amount of stone. Later aqueducts had a more sophisticated design, making greater use of concrete to reduce their volume and cost of construction. The Aqueduct of Segovia and the Aqüeducte de les Ferreres are of roughly similar length but use far fewer arches. Roman architects were eventually able to do away with "stacking" altogether. The Acueducto de los Milagros in Mérida, Spain and a similar aqueduct near Cherchell, Algeria utilise tall, slender piers, constructed from top to bottom with concrete faced with masonry and brick.

History

The construction of the aqueduct has long been credited to Augustus' son-in-law and aide, Marcus Vipsanius Agrippa, around the year 19 BC. At the time, he was serving as aedile, the senior magistrate responsible for managing the water supply of Rome and its colonies. Espérandieu, writing in 1926, linked the construction of the aqueduct with Agrippa's visit to Narbonensis in that year. Newer excavations, however, suggest the construction may have taken place between 40 and 60 AD. Tunnels dating from the time of Augustus had to be bypassed by the builders of the Nîmes aqueduct, and coins discovered in the outflow in Nîmes are no older than the reign of the emperor Claudius (41-54 AD). On this basis, a team led by Guilherm Fabre has argued that the aqueduct must have been completed around the middle of the 1st century AD. It is believed to have taken about fifteen years to build, employing between 800 and 1,000 workers.

From the 4th century onwards, the aqueduct's maintenance was neglected as successive waves of invaders disrupted the region. It became clogged with debris, encrustations and plant roots, greatly reducing the flow of the water. The resulting deposits in the conduit, comprised of layers of dirt and organic material, are up to 50 cm (20 in) thick on each wall. Nonetheless it seems to have continued to supply water to Nimes until as late as the 9th century.

Although some of its stones were plundered for use elsewhere, the Pont du Gard remained largely intact. Its survival was due to its use as a toll bridge across the valley. In the 13th century the French king granted the seigneurs of Uzès the right to levy tolls on those using the bridge. The right later passed to the Bishops of Uzès. In return, they were responsible for maintaining the bridge in good repair. However, it suffered serious damage during the 1620s when Henri, Duke of Rohan made use of the bridge to transport his artillery during the wars between the French royalists and the Hugenots, whom he led. To make space for his artillery to cross the bridge, the duke had one side of the second row of arches cut away to a depth of about one-third of their original thickness. This left a gap on the lowest deck wide enough to accommodate carts and cannons, but severely weakened the bridge in the process.

In 1702 the local authorities renovated the Pont du Gard to repair cracks, fill in ruts and replacing the stones lost in the previous century. A new bridge was built by the engineer Henri Pitot in 1743-47 next to the arches of the lower level, so that the road traffic could cross on a purpose-built bridge. However, the Pont du Gard continued to deteriorate and by the time Prosper Mérimée saw it in 1835 it was at serious risk of collapse from erosion and the loss of stonework.

Napoleon III, who had a great admiration for all things Roman, visited the Pont du Gard in 1850 and took a close interest in it. He approved plans by the architect Charles Laisné to repair the bridge in a project which was carried out between 1855-58, with funding provided by the Ministry of State. The work involved substantial renovations that included replacing the eroded stone, infilling some of the piers with concrete to aid stability and improving drainage by separating the bridge from the aqueduct. Stairs were installed at one end, allowing visitors to walk along the conduit itself.

There have been a number of subsequent projects to consolidate the piers and arches of the Pont du Gard. It has survived three serious floods over the last century; in 1958 the whole of the lower tier was submerged by a giant flood that washed away other bridges, and in 1998 another major flood affected the area. A further flood struck in 2002, badly damaging nearby installations.

Tourism and visitors

The Pont du Gard has been a tourist attraction for centuries. 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. From the 18th century onwards, particularly after the construction of the new road bridge, it became a famous staging-post for travellers on the Grand Tour and became increasingly renowned as an object of historical importance and French national pride.

The Pont du Gard was added to UNESCO's list of World Heritage Sites in 1985. The description on the list states: "The hydraulic engineers and ... architects who conceived this bridge created a technical as well as artistic masterpiece." By this time, however, the site was congested with vehicle traffic – which was still allowed to drive over the 1743 road bridge – and cluttered with illegally built structures and tourist shops. As the architect Jean-Paul Viguier put it, the "appetite for gain" had transformed the Pont du Gard into "a fairground attraction".

In 1996 the General Council of the Gard département began a major four-year project to improve the area, sponsored by the French government, in conjunction with local sources, UNESCO and the EU. The entire area around the bridge was pedestrianised and a new visitor centre was built on the north bank to a design by Jean-Paul Viguier. The redevelopment has ensured that the area around the Pont du Gard is now much quieter due to the removal of vehicle traffic, and the new museum provides a much improved historical context for visitors.

The Pont du Gard is today one of France's top five tourist attractions, with 1.4 million visitors reported in 2001.

The 19th century Roquefavour Aqueduct of the Canal de Marseille replicates the Roman architecture of the Pont du Gard.

See also

• Eifel Aqueduct
• Roman aqueducts
• List of aqueducts in the city of Rome
• List of Roman aqueduct bridges

References

1. Bromwich, James (2006). Roman Remains of Southern France: A Guide Book. Routledge. p. 110. ISBN 9780415143585.
2. Lewis, Michael Jonathan Taunton (2001). Surveying instruments of Greece and Rome. Cambridge University Press. p. 187. ISBN 9780521792974.
3. ^ Langmead, Donald; Garnaut, Christine (eds.). Encyclopedia of architectural and engineering feats. p. 254.
4. Sobin, Gustaf (1999). Luminous debris: reflecting on vestige in Provence and Languedoc. University of California Press. p. 205. ISBN 9780520222458.
5. Bromwich, p. 112
6. Sobin, p. 217
7. Bromwich, p. 111
8. Bromwich, p. 112-113
9. Deming, David (2010). Science and Technology in World History, Volume 1: The Ancient World and Classical Civilization. McFarland. p. 176. ISBN 9780786439324.
10. ^ Michelin Green Guide Provence. Michelin Travel Publications. 2008. pp. 297–298. ISBN 9781906261290.
11. Fabre, G.; Finches, I.L. (1989). "L'aqueduc romaine de Nîmes et le Pont du Gard". Pour le Science (40): 412–420.
12. "Pont du Gard - technical aspects". Site du Pont du Gard. Retrieved 2010-09-05.
13. Gimpel, Jean (1993). The cathedral builders. Pimlico. p. 75. ISBN 9780060911584.
14. ^ Bromwich, p. 119
15. ^ O'Rourke Boyle, Marjorie (1997). Divine domesticity: Augustine of Thagaste to Teresa of Avila. Leiden: BRILL. p. 105. ISBN 9789004106758.
16. Hill, Donald Routledge (1996). A history of engineering in classical and medieval times. Routledge. ISBN 9780415152914.
17. Bromwich, p. 110
18. Fabre, G, Fiches,J.-L., and Paillet, J.-L. 1991. "Interdisciplinary Research on the Aqueduct of Nimes and the Pont du Gard." Journal of Roman Archaeology 4, 63-88.
19. Le Pont du Gard remarquable Aqueduc, retrieved 2010-06-15
20. Homer-Dixon, Thomas F. (The upside of down: catastrophe, creativity, and the renewal of civilization). Island Press. p. 237. ISBN 9781597260657. {{cite book}}: Check date values in: |date= and |year= / |date= mismatch (help); Missing or empty |title= (help)
21. ^ Cleere, Henry (2001). Southern France: an Oxford archaeological guide. Oxford University Press. p. 96. ISBN 9780192880062.
22. ^ Rennie, George (1855). "Description of the Pont du Gard". Minutes of proceedings of the Institution of Civil Engineers. 14: 238.
23. ^ Bromwich, p. 117
24. Stirton, Paul (2003). Provence and the Côte d'Azur. A&C Black Publishers Ltd. p. 116. ISBN 039330972X.
25. Viguier, Jean-Paul (2009). Architecte. Odile Jacob. p. 11. ISBN 9782738123046.

External links

• Official Pont du Gard museum website
• Pont du Gard at Structurae
• Location of Pont du Gard (Michelin)
• Photos of the aqueduct le Pont du Gard
• Full Aqueduct (Uzès to Nîmes) website (in French)
• Pont du Gard: Picture Galerie
• 600 Roman aqueducts with 35 descriptions in detail among which is the Pont du Gard
• Ancient Places TV: HD Video of the Pont du Gard