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Mostar Old Bridge - Construction in the 15 th and Reconstruction in the 21th Century

The Old Bridge in Mostar spans the Neretva River in Herzegovina, Bosnia-Herzegovina's southeast region. Mimar Hayrudin, a Turkish architect, built it from 1557 to 1566 under the order of Ottoman Sultan Suleiman the Magnificent. Legend tells Hayrudin fled Mostar under a death threat from the sultan, who threatened to hang him if the bridge ever fell apart. During the Bosnian conflict in 1993, Croatian artillery bombardments destroyed the Old Bridge. Following its reconstruction in 2004, officials included it on the UNESCO World Heritage List in 2005. The governments of Turkey and Italy were the main sponsors of the project, as well as the government of Croatia. Recent research for the rebuilding project suggests that an earlier bridge existed on the same site, before the arrival of the Ottomans, under the mediaeval Bosnian state. The arch of the new limestone bridge, almost 29m long and 20m high, bends into a semicircle well known for its elegance and limestone construction contrasting the Neretva river’s deep green color. The Old Bridge symbolizes Mostar and attracts numerous tourists. In its long history, the bridge bore many names, such as "the New Bridge", "Sultan Suleiman's Bridge", "the Large Bridge" and, finally, "the Old Bridge", so the very name of the city, "Mostar", comes from two Slavic words, most (bridge) and premostiti (to span a river, bridgeable). The Old Bridge of Mostar (Stari Most) was a stone bridge of very slender and elegant shapes: its profile and its skyline were so thin and so high over the river waters that it was hard to believe that such a structure could be worked out of huge stone blocks. Built in tenelija stone, it was of a light colour tone, bright and changeable during daytime. The bridge was mainly conceived as a functional structure and its design was quite influenced by the morphol- ogy of the site, which is totally matched by its abutment walls, as well as interesting gothic like peak. The whole monumental complex, including the adjacent fortification towers, is totally part of the site, castled on the rocks and winding the banks, it is not the result of a single design work, but of a development over the course of time, that has followed, and historical events and the need to protect and preserve the bridge, that has marked the town even provided its name “Mostar”. The bridge had few esthetic devices and no ornamental element ; its architectural beauty and value were to be found in the simplicity and in the essentiality of the structure: the shapes of the bridge were not linked to any time, to any style or any fashion, in but the bridge of Mostar has always been admired as symbol. Two cornices, only, with an angled section profile, ran on each elevation and met at the keystone with a refined balance between tangency and jutting out: both of them had a protec- tive function against rain waters, and they marked different structural elements of the monument, being part of it and not pasted. A bigger cornice, on each side, determined the level of the bridge arch springer, prosecuting upstream and down- stream along the abutment walls. The stone surfaces were neither polished nor regular: they were perfectly cut and hand worked, but characterised by frequent ordinary structural inaccuracies which revealed their materiality and the fact that they were made of stone. Of more than one thousand stone blocks, there were no two elements of identical dimensions, and even the arch voussoirs were all different, with remarkable variations, due to the random, naturally-determined, availability of stones in the quarry. Un- doubtedly, most of the architectural beauty of this monument lay in the refined tuning in the globally compact appearance of the structure, caused by the thin joints of the masonry, and the unforeseeable and fragmentary close-view appearancedue to the small imperfections of stone blocks in the assem- bling of different shapes and sizes. The one-span bridge had an intrados curvature that was almost circular, with the centre adequate way approximately 296 cm lower than the east springer level ; but the circle shape may be not an adequate way to describe the curvature, which was modified at the level of the imposts to better match with the straight profile of the abutment wall, and was slightly raising at the key stone level. The exact original shape of the curvature vas desturbed by irregularities that may have been caused by settlements and by ordinary construction imperfections. The main dimensions of the bridge were as follows: the span was of 2871 cm on the north side and of 2862 cm on the south side and the rise of the arch was approximately of 1206 cm. The measurements were clearly often variable, and impost level of the bridge on the west bank was approxi- mately 12–13 cm higher than on the east bank. The load bearing arch had a depth of about 395 cm and an height of 80 cm, and was composed of 111 rows (a num- ber which was probably planned and not randomly obtained), and the rows contained between 2 to 5 voussoirs, (normal- ly 3–4). The voussoirs (arch stones) were of variable shapes and sizes, but the average stone block had the following dimensions: 40×80×100 cm. The arch and elevations of the bridge were made of tenelija stone (local limestone) and joined by mortar and metal reinforcing cramps and dowels. The use of forged iron devices to strengthen the structure was one of the peculiarities of the monument. They were assembled in various ways, they were applied almost to every element of the bridge. The bridge arch, at the top, was considerably higher (by about cm 270) than the adjacent street levels. The footpath over the bridge was steep, and tilted in such a way that all the architectural elements, e.g. spandrels, parapets and upper cornices, followed these directions until the top. The spandrel walls of the bridge were divided from the arch by a stone lower cornice, that followed the arch curvature, and were limited on top by the upper cornice, of straight but tilted profile. The lower cornice stones jutted out from the load bearing arch and determined the base from which the spandrel walls started ; at the same time the upper cornice was jutted from the spandrel walls. Finally, the parapets were almost aligned with the spandrel walls below them, but leaning slightly, outwards as they approached the top of the bridge, to give the optical effect of a wider footpath. The pavement was made in krecnjak stone and was characterised by transversal rib-steps to prevent slipping. The flooring was assembled on a mortar layer which, most probably, also had a waterproofing function together. On the structural side, the bridge was quite interesting, and an analysis of the inner elements shows the level of engi- neering skills at the time and the clever measures taken to ensure the long life of the structure. Main structural element of the bridge was the load-bearing arch, which was undoubtedly the part of the monument that required the greatest care and resources. The arch, due to its shape and the configuration of the dead loads above, was subjected to compressive loads. The stone blocks would have been perfectly adequate for the purpose, but additional devices were provided to strengthen the vault: forged iron dowels were inserted between adjacent voussoirs, and forged iron cramps were placed over the extrados and across the side joints. Thus each connection joint was strengthen either by mortar, or by metal reinforcements. A Project Coordination Unit (PCU) was formed by the World Bank, UNESCO and City of Mostar, as a specialized agency responsible for performing professional and other tasks to coordinate the project to the build the Old Bridge and other structures within the Pilot Cultural Heritage Projects for Bosnia and Herzegovina. Most of the stone elements of the bridge were made in tenelija stone (from the Mukoša quarry). One of the first tasks of the contractor for the actual reconstruction of the bridge was to prepare the Site around the Old Bridge. After determining the best possible position for placing the main crane, it was necessary to investigate the soil beneath. The first actual task on site was to remove the existing parts of the arch. The workers, using hand tools, separated each stone individually from the mortar, silicon and soil. One of the most important materials used in constructing the bridge was lead. The solidity was achieved with the use of metal cramps and dowels, fixed within the stone cavities with lead. One of the most important and most delicate procedures while ebuilding the bridge was pouring the lead into the voussoir stones. Lead was poured through channels into the “hidden” (already inserted) dowels between the rows of the arch. The channels had to be dry and clean, and the lead had to be poured at the optimum rate. This was the final procedure for consolidation of he bridge.

Mostar, Old Bridge, The Reconstruction of the Old Bridge in Mosta

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