Nysa Bridge

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Coordinates: 37 ° 54 ′ 12 ″  N , 28 ° 8 ′ 44 ″  E

Nysa Bridge
Nysa Bridge
Looking downstream to the west
use Substructure for the theater forecourt
Crossing of Cakircak
place Nysa ( Turkey )
construction Arch bridge with vaulted vaults
width Approx. 100 m
Clear width 5.7-7 m
Arrow height 2.95 m
height 5.9 m (to the apex)
location
Nysa Bridge (Turkey)
Nysa Bridge

The bridge of Nysa is a Roman river construction over the Cakircak brook in Nysa ( Caria ), today's Sultanhisar in Turkey . The 100 m long, tunnel-like structure from the late imperial era was the second largest of its kind in antiquity after that in Pergamon .

Classification

The Nysa Bridge spans the Cakircak brook running across the ancient city area for a total length of about 100 m, which gives it the character of a tube or a tunnel in the eye of the casual observer . Despite the outward appearance, however, the structure, which was built continuously above ground, is a river superstructure, i. H. a particularly wide bridge that combines bridge and tunnel elements: while the hydraulic and hydrological properties are comparable to a tunnel, the arch resting on two abutments corresponds structurally to a bridge, the above-ground position of which meets the technical challenges typical for tunnel construction such as the determination of the The direction of tunneling underground or the precaution against ceiling or water ingress was completely eliminated. In ancient times, river superstructures to cover longer stretches of a watercourse were primarily used to enlarge the inner-city area. In the case of Nysa, the purpose of the building was to create a spacious forecourt for the theater near the stream .

Dating

The Greek geographer Strabo (63 BC – 21 AD), who lived in Nysa, described a secret, water-bearing passage in the city, although it is unclear whether this meant the river overbuilding that still exists today. On the basis of a building inscription on the north wall of the tube not far from the bend, which points to one of the builders (“Work of Praülos up to this point”), the bridge of Nysa is dated to the late imperial era.

construction

The Nysa Bridge consists of a single, 5.7 m wide tube, which increases to 7 m at the mouth hole on the mountain side. The stitch height of the round arch , which is about 3 m above the foundation base, is 2.95 m, so that the total height is 5.9 m. The vault consists of unworked stones in a mortar bond and rests on a substructure made of stone blocks of different sizes with a size of 0.3–0.9 × 1.0–1.4 m.

The originally continuous river superstructure has now collapsed in two places: In the upper area, the closed vault has remained 75 m long, with the tunnel making a kink after 25 m. The covered section is followed by a 10 m wide collapse area, after which the overbuilding continues as a single arch, which, due to its isolated location, is often incorrectly referred to as an independent bridge construction. The end of the tube on the valley side also collapsed, so that the total width of the bridge was probably 100 m - a bridge width that in ancient times was only exceeded by the double structure in Pergamon . For comparison: the width of normal Roman bridges that did not function as substructures usually did not exceed 10 meters.

In its further course through the urban area of ​​Nysa, the Cakircak also crossed the stadium , in which water competitions could be held. Two bridges above and below the stadium have been preserved.

Flow capacity

The limit capacity of the river overburden during flooding was the subject of hydraulic and hydrological studies. With a gradient of 3.3%, a maximum flow capacity of 290  m³ / s of the tunnel was determined before the Cakircak brook dammed up, pressurized the structure and caused damage. Assuming this value is based on the fact that the Cakircak is 6 km long, has an average gradient of 19% and covers a catchment area of 4 km², the following average return intervals result depending on the method :

  • 17,500 years (Günerman method)
  • 10,500 years (DSI method)
  • 13,000 years (Mockus method)
  • 68,000 years (Snyder method)

According to this, statistically every 13,500 years - the value that Grewe describes as the " arithmetic mean " - a flood that exceeds the capacity of the Nysa bridge could be expected.

Individual evidence

  1. ↑ a b Grewe, Klaus et al. (1994), p. 352
  2. ↑ All information: Grewe, Klaus et al. (1994), pp. 348f.
  3. ↑ a b Grewe, Klaus et al. (1994), p. 350
  4. ↑ Archaiologikon Deltion 1921-22, 84: Π̣ραΰ̣λου ἔργον | ἕως ὧδε
  5. ^ Grewe, Klaus et al. (1994), p. 351
  6. ↑ a b All information: Grewe, Klaus et al. (1994), p. 351
  7. ^ Colin O'Connor: Roman Bridges , Cambridge University Press 1993, ISBN 0-521-39326-4
  8. ^ Grewe, Klaus et al. (1994), pp. 351f.

literature

  • Klaus Grewe , Ünal Özis and others: The ancient river structures of Pergamon and Nysa (Turkey). In: Ancient World . Vol. 25, No. 4, 1994, pp. 348-352.
  • Ünal Özis et al .: Flood Flows and Capacities of the Historical Pergamon and Nysa Tunnels in Anatolia. In: International Association for Hydraulic Research (IAHR), 18th Congress Proceedings. Vol. 6, Cagliari 1979, ZDB -ID 998222-x , pp. 696-698.
  • Ünal Özis: Ancient Water Works in Anatolia. In: Water Resources Development. Vol. 3/1, 1987, ZDB -ID 1251957-1 , pp. 55-62.

See also