Bridge at Limyra
Coordinates: 36 ° 20 ′ 56 ″ N , 30 ° 12 ′ 23 ″ E
| Bridge at Limyra | ||
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| Official name | Kırk Göz Kemeri | |
| use | footbridge | |
| Convicted | Street Limyra - Attaleia | |
| Crossing of | Alakır Çayı | |
| place | Near Limyra ( Turkey ) | |
| construction | Segment arch bridge in composite construction | |
| overall length | 360 m | |
| width | 3.55-4.30 m | |
| Number of openings | 28 | |
| Pillar spacing | 11.60-14.97 m | |
| Clear width | 9.50-12.87 m | |
| Arrow height | 2 m | |
| Pillar strength | 2.10 m | |
| Arch thickness (vertex) | 0.8 m | |
| Arrow ratio | 5.3-6.4 to 1 | |
| Flow profile | 4.5–6.1 to 1 | |
| Arch slenderness | 11.9-16.1 to 1 | |
| Load capacity | 30 t + 500 kp / m² | |
| construction time | Presumably late 2nd to 3rd century | |
| Status | Endangered | |
| location | ||
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| Above sea level | 19.66 m | |
| Elevation and supervision of the arch bridge | ||
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The Roman bridge at Limyra ( Turkish: Kırk Göz Kemeri ) in what is now south-western Turkey is one of the oldest segment arch bridges in the world. The 360 m long stone bridge crosses the Alakır Çayı River near the ancient city of Limyra in Lycia . Its 26 segment arches are largely buried today. They have an arrow ratio of 5.3 to 6.4 to 1, which gives the structure an extremely flat profile and was only achieved again in the late Middle Ages (for example at the Ponte Vecchio ) with 6.5 to 1. Despite its outstanding technical and historical significance, the bridge near Limyra is little known; The increasing destruction of the building prompted the German Archaeological Institute (DAI) to conduct the only field investigation to date.
exploration
There are no reports of ancient news about the bridge. The first descriptions of the structure appear in European travelogues of the 19th century: Charles Fellows described the bridge with 25 arches during a visit in May 1840; Spratt and Forbes did the same two years later. An Austrian expedition with the participation of Otto Benndorf interpreted the building in 1882 as part of an ancient road from Limyra to Antalya to the east . However, no plans or sketches were made at the time.
The first and so far only scientific survey of the bridge was carried out by Wolfgang Wurster and Joachim Ganzert on two consecutive days in September 1973 and supplemented by further on-site visits in the three following years. The results were published in 1978 in the Archäologische Anzeiger des DAI, expressly also to point out the increasing endangerment of the bridge, which had remained almost intact:
“Recently, citrus plantations have been planted in this fertile alluvial land; greenhouses for early vegetables are now being built in the east of the bridge. The bridge is very endangered by the beginning, intensive agriculture in the area. The residents remove stone material from the still intact bridge covering; Bulldozers for creating irrigation canals tear open the bridge and crush the stone pavement with their caterpillar chains. "
The engineer O'Connor briefly summarized the DAI report in his English-language monograph on Roman bridge construction in 1993 and also emphasized the exceptional character of the bridge. Further scientific discussions with the bridge at Limyra are not known.
Topographical and traffic-related location
The Roman bridge crosses the Alakır Çayı 3.2 km east of the ruins of Limyra (measuring point: theater ) and 3.8 km north of the current sea coast near the modern road from Turunçova to Kumluca ; the ancient name of the river is not known. The local topography is determined by the foothills of the Toçak Dağı mountain range, which merge into the flat alluvial land of the Finike Bay . In this transition area, the bridge was built just above the point where the narrow river valley opens up to the wide estuary and flood water hinders the crossing during the rainy season. While the bridge ends in the gravel plain in the east, the western end is presumably on the rising rock to protect against flooding. The resulting sharp bend in the road to the south offered an inexpensive way to block the road. Nowadays the Alakır Çayı only flows under three arches of the Roman Bridge (as of 1978). In modern times, the Alakır Barajı dam was built upstream for irrigation purposes and flood protection.
In contrast to other Roman provinces , the ancient road system in Lycia was poorly developed. While the north-south traffic ran mainly over the few river valleys, the west-east routes, unlike today, mostly ran over the mountain heights. The route from Limyra via the Alakır Çayı into the neighboring Pamphylia to Attaleia was likely to have played a special role, since both regions combined formed the province of Lycia et Pamphylia up to the 4th century AD . Compared to the main arteries of the empire, the road connections in Lycia, 3–4 m wide, were of course much more modest and were probably restricted to pedestrian and pack animal traffic. It also fits that the road surface of the bridge at Limyra does not show any wagon tracks; Even traces of a railing or a parapet could not be detected on the building.
construction
With a length of 360 m, the bridge near Limyra is the largest preserved engineering structure from antiquity in Lycia. The bridge has 26 uniform segment arches, which consist of two superimposed, radially walled brick layers. At the eastern end of the bridge, instead of the former 27th segment arch, there are two smaller, semicircular repair arches of later date, which were built with just a simple brick layer. The original, flat approach of the collapsed arch is still clearly visible in the pillars.
During the archaeological exploration, Wurster and Ganzert found the entire structure to be buried with river deposits up to the fighter points ; Attempts to expose were not made. Only two of the 28 bridge arches were so open that the clear width and the pier thickness could be measured directly. However, it was possible to calculate the center distances of all pillars from the arch sections that were not buried.
Segmental arches and pillars
The spans of the segment arches, i.e. the distances between the pillars' centers, range from 11.60 m to 14.97 m (arch 2 or 26 - counting in the west (orographic right) beginning). Four groups of similar size can be formed with the following average widths :
- 11.60-12.30 m (4 arches: 2, 3, 7, 21)
- 12.75 m (14 arcs: 5, 9–15, 17–19, 22–24)
- 13.10 m (4 arches: 1, 4, 6, 8)
- 13.60 m (3 arches: 16, 20, 25)
It is unclear why the distances between the pillar axes of the bridge differ from one another in groups; they cannot be explained as an adaptation to the nature of the river bed . The fluctuations could indicate a multiple use of different falsework in the construction of the barrel vault .
Wurster and Ganzert determined the pillar width to be 2.10 m in only one case (between arches 26 and 27). If you subtract this value from the 12.75 m wide normal curve, the result is a clear width of 10.65 m. Since all segment arches have a pitch of around 2 m, the ratio of clear width to height in the Limyra bridge is an unusual 5.3 to 1.These flat arches were unique in stone bridge construction at that time and remained until the return of segment arch bridges in Italy in the 14th century Century unsurpassed. The largest arch of the Limyra Bridge even spans a length that is 6.4 times its height. The elevation of the two repair arcs , on the other hand, is 2.7 to 1, which is still in the normal range of semicircular arcs .
Bridge height and level
The total height of the bridge could not be determined due to its burial condition, but the distance from the fighters to the road surface could be determined; it is only 3.25 m.
The bridge level forms an almost horizontal plane: While the roadway from arches 1 to 20 is at a level of 20.05–20.55 m above sea level. M. is located, it falls slightly in an easterly direction at the remaining six segment arcs to 19.94 m to 19.66 m. Given the length of the structure, the authors classify the fluctuations as minimal. Since there is no evidence of a later lowering of the structure, the uniform height suggests that the pillars were carefully leveled and that the foundation was solid. In contrast to this, the longitudinal axis of the bridge differs from arch to arch in some cases significantly from the main direction.
Statics
Remarkably, the support line for the dead weight is almost identical to the curve of the arch axis. The static examination of the segment arch bridge proves the great load-bearing capacity of the construction:
“According to today's classification, the bridge could take over the loads of bridge class 30 according to DIN 1072 ; that would mean that it could carry a 30-ton truck on one arch and an additional 500 kgf / m² on the remaining surface of the arch . The bridge was therefore dimensioned with great certainty for ancient traffic. "
Structure
The bridge at Limyra was constructed in a composite construction from bricks , stone blocks and rubble stones .
Brick arches
The bricks of the segmental arches are made of yellow-red clay to which fine brick chippings have been added. The rectangular panels have a format of 40 × 50 cm, are approx. 5 cm thick and stand upright with the shorter side in the arch structure, so that the double-walled arches have a total thickness of 80 cm. The binding material in the 4 cm thick joints is hard lime mortar with the addition of coarse brick chippings and fine gravel . The two semicircular arches were built with slightly smaller bricks, and in some places the original bricks from the destroyed segmental arch were reused. The fighting stones are smoothly hewn limestone blocks with an inclined support surface for the arch attachment.
The two-layer arched vault allowed efficient use of the falsework, which could be moved to the next arch opening after the lower brick layer had been completed:
“Bringing up the two layers of the double brick arches separately in two phases had two advantages. In the first phase, the falsework only had to bear the load of the lower arch layer and could therefore be dimensioned weaker. In the second phase, the load of the upper layer could already be borne by the lower vault layer, so the falsework was already available for another bridge opening. "
Wall shell
As far as can be seen, the bridge from opening 2 to 21 has a four-layer brick cladding, on which a mortared quarry stone masonry is attached. Between the 22nd and 26th arches and at the two bridge ramps , however, the wall shell is made of stone blocks. The repaired fields 27a and 27b differ from the brick and quarry stone cladding in the west and the ashlar shell in the east due to the small size of the built-up rubble stones and the disorderly incorporated bricks. The underside of the arch of opening 26 still shows the projection-like support for the falsework.
The inside of the bridge above the arches and pillars consists of a composite of rubble stones and large river pebbles with lime mortar.
band Aid
Only 30-40 cm is over the apex of the arcs of the large and irregular limestone slabs existing bridge patch that both sides 10 cm beyond the edge of the bridge projects. The use of small river pebbles as paving reveals repair features on the two semicircular arches. The bridge path is 3.55 to 3.70 m wide and increases to 4.30 m at the bridge ends.
Dating
The chronological classification of the bridge at Limyra is made considerably more difficult by its extraordinary character within the Roman building tradition and the lack of comparative studies of Roman bridges. Wurster and Ganzert cite the following characteristic construction features of the bridge as a starting point:
- Multi-field system with the same field width and horizontal bridge runway with low ramps at the bridgeheads
- very flat segmental arches made of double, radially layered brick vaults
- Mortar masonry
- Outer shell predominantly quarry stone with brick penetration , partly isodome ashlar masonry
- particularly large-format flagstone paving.
In contrast, most of the Roman stone bridges had ashlar cladding and rested on vaulted vaults, which for a long time also dominated the construction of vaults in Lycia. In contrast to the massive and towering semicircular arch bridges, which were typical of Roman construction technology , the bridge near Limyra with its flat segment arches has a significantly lower and more elongated appearance, so that Wurster and Ganzert "tentatively" date the building later in time Justinians I (6th century), for whom the use of brick and stone associations in Lycian regional architecture is documented.
On the other hand, since this mixed technique was already used in the nearby aqueduct of Aspendos in the 3rd century AD and the Romans were well aware of segment arch bridges, as the two building researchers themselves explain using three examples, it would also be an earlier date of origin at the end of the 2nd or possible in the 3rd century. This early dating seems more likely from today's perspective, after seven more segment arch bridges from Roman times have been documented in the meantime.
The remains of the Roman bridge at Kemer , which also dates back to the 3rd century and whose construction has some similarities with the Limyra bridge, are located in the neighboring Xanthos river valley .
See also
literature
- Colin O'Connor: Roman Bridges. Cambridge University Press, Cambridge 1993, ISBN 0-521-39326-4 , p. 126 (E23).
- Wolfgang Wurster , Joachim Ganzert: A bridge near Limyra in Lycia. In: Archäologischer Anzeiger . 1978, pp. 288-307.
Web links
- Bridge at Limyra. In: Structurae
- Bridge at Limyra in the Arachne archaeological database
- Traianus - Technical investigations of Roman buildings
Individual evidence
- ↑ Henryk Ditchen, Jozef Glomb: Famous bridge builders: their times and monuments , logos Berlin, 2011, ISBN 978-3-8325-3271-0 , page 82
- ↑ a b c d e f Wurster & Ganzert (1978), p. 288
- ^ Wurster & Ganzert (1978), pp. 289f.
- ↑ O'Connor (1993), p. 126: “Wurster and Ganzert describe the remarkable bridge near Limyra… The outstanding feature of the bridge is that the arches are segmental… It is believed that the bridge is Roman. If this is the case, then it is one of the few truly segmental Roman stone arch bridges, ... "
- ^ Wurster & Ganzert (1978), pp. 288f.
- ↑ a b c d e Wurster & Ganzert (1978), p. 289
- ↑ a b c d Wurster & Ganzert (1978), p. 303
- ↑ a b c d e f Wurster & Ganzert (1978), p. 295
- ^ Wurster & Ganzert (1978), pp. 288, 291
- ↑ a b c d e Wurster & Ganzert (1978), p. 291
- ↑ a b Wurster & Ganzert (1978), p. 290
- ↑ a b Wurster & Ganzert (1978), p. 291f.
- ↑ a b c d e Wurster & Ganzert (1978), p. 292
- ↑ 12.75 - 2.10 = 10.65 m (Wurster & Ganzert (1978), p. 292)
- ↑ 10.65: 2.00 = 5.3 (Wurster & Ganzert (1978), p. 292)
- ↑ (14.97 - 2.10 m): 2.00 = 6.4 (Wurster & Ganzert (1978), p. 292)
- ↑ 5.30: 2.00 = 2.7 (Wurster & Ganzert (1978), p. 292)
- ^ Wurster & Ganzert (1978), p. 292, Fig. 5; P. 295
- ↑ a b Wurster & Ganzert (1978), p. 295f.
- ↑ a b Wurster & Ganzert (1978), p. 296
- ^ Wurster, Wolfgang W. & Ganzert, Joachim (1978), p. 297
- ↑ a b c Wurster & Ganzert (1978), p. 299
- ↑ a b c d Wurster & Ganzert (1978), p. 293
- ^ Wurster & Ganzert (1978), p. 299f.
- ^ Wurster & Ganzert (1978), p. 301
- ^ Wurster & Ganzert (1978), p. 300, fn. 10
- ^ Wurster & Ganzert (1978), pp. 301f.
- ^ Wurster & Ganzert (1978), p. 302
- ^ Wurster & Ganzert (1978), pp. 302f.
- ↑ Wurster & Ganzert (1978), p. 302, fn. 13; 303, 18; 304-307
- ^ Wurster & Ganzert (1978), p. 300
- ^ O'Connor (1993), p. 171
- ↑ Wurster & Ganzert (1978), pp. 304-307
