Nysa Bridge | |
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Coordinates | 37°54′12″N 28°08′44″E / 37.903405°N 28.145514°E |
Carries | Substructure for theatre square |
Crosses | Cakircak |
Locale | Nysa ( Sultanhisar), Caria, Turkey |
Characteristics | |
Design | Arch bridge |
Material | Stone |
Width | c. 100 m |
Longest span | 5.7–7 m |
No. of spans | 1 (bottom vault) |
Clearance below | 5.9 m |
Location | |
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The Nysa Bridge is a late imperial Roman bridge over the Cakircak stream in Nysa (modern Sultanhisar) in the ancient region of Caria, modern-day Turkey. The 100 m (328 ft) long substructure was the second largest of its kind in antiquity, after the Pergamon Bridge. [1]
The Greek geographer Strabo (63 BC–AD 21), who lived in Nysa, mentioned a secret water conduit in the town, but it remains unclear whether he meant the existing tunnel-like bridge. [2] An inscription at the northern wall of the tube, close to a bend after 25 m (82 ft), indicates a construction date in late imperial times. [3] It reads "Work of Praülos until this point". [4]
The Nysa Bridge served as a substructure for the area in front of the city theatre, which lay close to the Cakircak stream. [5] It was built as a two-level structure: the bottom vault spanned the brook. On top of it a row of arches connected the two hills that formed the urban area. The ground arch spanned the stream on a length of some 100 m (328 ft), giving the bridge the appearance of a tube or a tunnel, although it was constructed entirely above ground. It consists of a single, 5.7 m (19 ft) wide vault whose uphill mouth widens to 7 m (23 ft). The overall height of its semi-circular arch is 5.9 m (19 ft), featuring a rise of 2.95 m (9 ft 8 in). The vault is made of rubble stone laid in mortar, resting on a substructure of ashlar stone blocks of varying size (0.3–0.9 x 1.0–1.4 m). Originally featuring a continuous vaulting, it is collapsed today between m 75 and 85, and again at the downhill exit. The remaining, isolated structure at the downstream side has often been incorrectly referred to as a bridge of its own. [6] The Nysa Bridge was the second largest bridge substruction of its kind in antiquity, only surpassed by the nearby Pergamon Bridge. [1] By comparison, the width of a normal, free standing Roman bridge did not exceed 10 m (33 ft). [7]
In its further course, the Cakircak also ran through the city stadion, so that naumachia could be given. There are remains of two other ancient bridges both up- and downstream. [2]
The capacity limit of the Nysa Bridge in case of floods has been the subject of hydraulic and hydrological research. The gradient of the tunnel was calculated as 3.3% with a maximum discharge capacity of 290 m³/s. Exceeding this limit puts the bridge under internal pressure and damages the structure in the process. Considering that the Cakircak is 6 km (3.7 mi) long, with a median gradient of 19% and a drainage basin of 4 km2 (1.5 sq mi), the following median intervals were calculated, depending on the method employed:
The study came to the conclusion that statistically every 13,500 years, a value which has been referred to as the " arithmetic mean", floods are to be expected which would exceed the capacity of the bridge. [8]
Media related to Nysa Bridge at Wikimedia Commons