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NEWSLETTER 01 - 29.07.02

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The Mostar story


The oldest written testament of the existence of medieval Mostar date back to the 15th century, prior to the invasion of the Ottoman Turks. The testament was the work of Herceg Stjepan Radivoj (the Duke of Herzegovina).

Mostar developed at a rapid pace, eventually taking the primacy of Blagaj. Mostar developed into a strategic and commercial hub becoming the meeting point of roads from the sea connecting the south to the north and northern regions to the western regions.

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The first medieval bridge in Mostar was a wooden suspension bridge which was very unstable and of fragile construction. When The Turks invaded and conquered Mostar, they used the old wooden bridge for crossing from the east bank of the Neretva river to the west bank. (It is rumoured that the bridge swayed so much, that to cross it, one would be taking his life in his own hands). There are some notes pertaining to the construction of the wooden bridge but as to their whereabouts is another matter, we know that the bridge was made from wood without any pilasters and was suspended from chains. Remains of this bridge are still visible on the left bank (east) and south of the Old Bridge just below the museum (“Zavicajni Muzej”) Today we can find ruins from that era (that is, prior to the Turkish invasion). The foundation walls used for carrying the chains are still visible on the left (east) bank of the river, on the right (west) bank there are no traces of buttress walls. In conclusion we know:

In the 16th century Sultan Sulejman the Magnificent ordered the construction of a new bridge in Mostar. From the reports of Hadzi Kalfa, the bridge was completed in 1566 which coincidentally was the last year of Sulejman's reign.

Evlija Celebija the famous Ottoman traveler and writer produced more information on the Old Bridge, claiming it was built by Kodza Mimar Sinan, son of Aga Abdulmenan under the orders of Sulejman the Magnificent. Evlija also mentions that there was plumbing within the bridge which was installed by a master craftsman; truly remarkable. However, Evlija erred as to the architect of the bridge. A Turkish historian uncovered a document in which it clearly states that the bridge was built by Hajrudin, Sinan's student.

The arch vault is built of voussoirs with radial links that are equal to the height of the front arch. The voussoirs were placed out in horizontal rows, with three or four in one line [from two to five per row even if frequently is three-four], some of these stones exceeded 2m in length. The builder knowing that the structure, being of elegance, was very fragile, that he made absolutely certain that no unnecessary stones were used. He made the front walls on both sides 80cm thick [variable measure] and refused to fill the cavities or core of the bridge with heavy stones and soil which was the usual procedure on other bridges, (Zepa bridge being a prime example), instead of this he introduces one middle rib and where possible he incorporated cavities to reduce the weight of the bridge. This method of construction was used on the "Kriva Cuprija" bridge which straddles the Radobolja brook, a tributary of the Neretva river. However, circumstances were different for the Old Bridge, which required a more sophisticated sense for weight and balance of the construction [structurally speaking this statement is not proved]. Viewing the bridge in cross-section we can appreciate the method of construction: a cavity on the upstream (north) side of the bridge measures 20cm wider than the one on the downstream (south) side [today it is not possible to verify the above measure and peculiarity, which anyhow might have been presumably variable along the structure]. Two other cavities were discovered during maintenance work being done after World War II [even about this peculiarity no verify and location is currently possible].

The transition from the arch to the front walls is highlighted with a decorative profile [lower cornice] 15cm in height; the profile extends 15cm from the face of the bridge [see following paragraphs for detailed notes about measures and technical data]. The front faces of the bridge are on the same layer as the extended profile and are composed of tenelija ashlars in horizontal rows. These ashlars continue partly down the side walls of the bridge.

The bridge was partly annexed on the front rows of stone on the right side (west bank) in order to lower the slope. This wedge shape form has three rows of stones in its final spot, and its joints are perpendicular to the primary steep. It is difficult to tell whether this correction was made after or during the construction of the bridge, but we can assume that it was the second option, because there are no visible marks of different procedure in the following construction.

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The steep of the bridge is transparent on the façades, by the profile [upper cornice] similar but thicker from the one above the arch (approximately 20-24cm thick) [variable measure]. This profile is also going over the front walls for 14cm. From the top of the bridge level is steeply falling to the left and right side. The highest spot is on 60.39m above the see level, that means 20.34m above the summer river level [variable measure]. On the right side it goes down to 57.24m, and on the left 57.05m [see following paragraphs for detailed notes about measures and technical data].

The path over the bridge is from the both sides framed by stone plates parapet 23-25cm thick [variable measure], and 94.50cm height [variable measure]. The parapet is tighten to a profile in same layer as the front walls, so the profile [upper cornice] stays plastically accented from the top and from the bottom. It is interesting to note that the stone parapets were chamfered on one side and placed on top of the side walls [spandrels] with the chamfered end of the stone facing away from the bridge.

Why this was done, we do not know, we may presume that was the fine sense for optical effects, as in ancient pilasters or similar.

The path is paved by regular (big and small) stone plates, from the firm white limestone [not limestone but krecnjak stone], with cross threshold, which keeps from slipping of the people or horses. The stones are densely compressed and anchored with mortar, so that only few drops of water were allowed into the construction. The threshold end before the parapets, so that the rain would drain quickly and avoid making puddles. Underneath this pavement there is the layer of cm15 of gravel stone with mortar made of red earth and lime. This lowest level is leaned on the big stones with which the cavities were vaulted with [for technical details concerning different layers below pavement refer to following paragraphs].

In following years, we can’t tell exactly when, most possible during the further reconstruction [maybe Austro-Hungarian period], the iron fence was added to the existing stone parapets. . This was more than likely done for safety reasons while crossing the bridge.

The side walls which are attached to the supports from down and upstream side, and from some angle are protecting the parts of the shore, to which the bridge is spanning, from the water strokes, are mostly made to the same height as the front walls of the bridge. The technique of building these walls isn’t all alike and not similar to the masonry of the bridge, so we can presume that it must have been rebuilt or repaired sometimes during the centuries. This is mostly visible on the side walls on the left shore. Just on that place the two signs about the reconstruction were found.

A community formed around the Old Bridge and developed into a strategic and commercial hub. The surrounding mountains, the deep rocky river bed of the blue-green Neretva, houses composed of various geometrical shapes, the two towers, the bridge itself, all made from the same grey-white type stone, slate type covered roofs of the same stone only lighter in shade, leaves a deep impression on the observer.

The towers of the bridge were considered to be construction parts that were necessary for the support of the Old Bridge. However, this was over exaggerated and not the case, the towers provided an artistic flare to the bridge and they did not serve as supports.

There are disagreements as to the dates of construction of the towers. The facts based on the two signs (mentioned earlier in this text) the bridge being 974 (1566) and the towers 1087

(1676). Some historians claim that the left tower on the east bank was built prior to the tower on the west bank. The masonry also reveals different periods of building. The bridge was made of precisely cut stone (as most other public buildings) whereas the towers were constructed of gravel stone and other half worked materials.

From historical evidence it became obvious the two towers existed in 1452 (some writers describe them even 84 years before the bridge).

The assumption that the towers are from the pre Turkish era were confirmed by researches completed on the site. Research was first carried out on the tower situated on the right bank of the Neretva. After the mortar was removed from the tower it was found to contain gear grindings, similar traces were found on the left tower which proves an older dating of the construction of the towers. This fact indicates that the towers where from the medieval Bosnian State era and later modified for the needs of the Ottoman Turks. The first renovations of the towers were made during the reign of Mehmed the II el-Fatih also he carried out renovations on the then existing old wooden bridge. During that time the whole town of Mostar was converted into a fortification.

The towers on either side of the bridge had a specific shape. half cylinders with the flat side facing the bridge. The left tower (east bank) known as the Tara or Hercegusa, was transformed into a storage area for ammunition and powder, during the occupation in 1878. The right tower (west bank) was called the Halebinovka or Celovina tower. The lower portion of the Halebinovka tower served as a prison while the upper floors were used as observation posts. Venetian warriors attacked Mostar in 1652, 1693 and 1694. After the first attack it was evident that it would be necessary to take measures to ensure the protection of the city as well as the bridge crossing.

We know very little about the repairs made on the bridge outside of the fact that Hajrudin's work was so solid that it resisted wear and tear through the centuries. We can assume that the only fragile spot on the bridge was on the left (east) support and side walls which indicated traces of building repair.

Despite the fact the “sign” (mentioned earlier in this text) and dated 1676 mentions no repair work on the bridge the facts prove that indeed that repair work was carried out at that time. The second sign mentions that repairs on the bridge were completed in 1150 (1736-1737).

During the Austro-Hungarian occupation of Mostar area many renovations were made. The sloping ground on either side of the bridge was raised by 80 cm. in order to accommodate the current traffic problems. The path on the bridge was also increased and re-surfaced. To adapt to the current situation, main streets leading to the bridge were increased in elevation, also the elevation of the entrance doors of the bridge were increased. After World War II, reconstruction around the bridge area continued and the remains of Austro-Hungarian intervention were removed. During the Austro-Hungarian period damaged stones on the bridge were repaired using cement mortar, this was a poor solution as the mortar left stained dark spots on the bridge.

During World War II plans were made to destroy the Old Bridge, luckily these plans were discarded. However, some damages, due to mine slots, were done and even after mortar repairs, water could penetrate the construction leading to further damages. The situation was considered very serious therefore, restoration began in 1955. Supports were restored on either side of the bridge and damaged walls and empty cavities fully repaired, the restoration was completed by the end of 1965. The second stage of restoration involved the arch of the Old Bridge using the injection method, with a special mixture of 82.50% cement, 15% mixture of stone flour composed of limestone tenelija, 2.50% bentonit. The required volume of this mixture for the repairs came to 7 cubic metres which gives us a good indication that the arch (vault) was severely damaged also cracks were appearing in the stone and mortar joints. At this time damaged stones on the vault as well as on the façade were replaced, cavities of cement mortar were removed and replaced with a special mixture that blended in with the colour of the tenelija stone.


The Old Bridge of Mostar was destroyed in November 1993 by shelling during recent war events; the moments in which shelling were ongoing have been filmed and from that documentation it has been possible to gather some technical data and observations.

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From analysis of the remaining portions of the bridge located by the east abutment, it is possible to observe an higher surface deterioration on the north side than in the south one, but, as far as it was possible to see from the movie, shelling were coming from south side and hit mostly the south east portion of the bridge over the arch reins: nowadays the widest remaining portions of the bridge are located on that side. This seems quite strange but it is most likely that shootings were directed also to the north elevation during other war attacks, and this is the reason why the bridge had been protected by tyres, (temporary structures over the footpath were instead aimed at the protection of the people from shootings). Moreover shelling was performed with accuracy almost on the same spot in order to cause the collapse using the minimum numbers of shells and the structure was divided in two main parts: a small one below the arch reins by the east bank, (still built-in and on-site), and a big one which ruined wholly in the river.

From observations of the movie it is possible to note how shells have gradually brought to the bridge collapse:

§ the load bearing arch was the main target element of the shelling: a wide portion of it was destroyed before final collapse, (from the reins to the key stone for a thickness of about a meter);

§ other shelling which were higher than the target perforated the spandrel wall with escaping of fill;

§ the attack has been performed by people that knew the basic functioning of a bridge structure;

§ shelling was performed with the aim of causing the collapse of the bridge and not of ruining the bridge; the bridge collapsed when a shell broke definitely the continuity of the load bearing arch.

The above mentioned movie has helped the work for the repositioning of the recovered stones since it has been possible to determine the voussoirs that were most likely definitely lost and reduced to powder due to direct hit.

The renovation program on the Old Bridge was in the works for ten years and many reports were written by D. Krsmanovic, H. Dolarovic and Z. Langof, these reports and all technical data are available today.


The Old Bridge in Mostar was the inspiration for many poets and writers it also created many legends. Evlija Celebija talks of the bridge as well as the “cardak”. The cardak was on the west bank of the Neretva, being the meeting place of well educated people of that time. Today a coffee bar stands where the cardak use to be.

From ancient times until today the Old Bridge has remained a symbol of Mostar, it remains as an attraction for its inhabitants as well as for the many travellers and tourists. The tradition of jumping from the top of the arch down to the river will remain a symbol, carried by the generations to come, forever, as long as the Neretva river and the “Stari Most” (Old Bridge) exist. […]”

 


The Reconstruction


PCU is a specialized agency whose responsibilities are performing professional and other jobs for coordination of the project of the building of the Old Bridge and other structures within Pilot Cultural Heritage Projects of Bosnia and Herzegovina.

PCU has three components: 1. Building of the Old Bridge, (UNESCO), 2. Rebuilding of neighbourhood (AGA KHAN TRUST FOR CULTURE), 3. Rebuildnig of other neghbouring structures.

The following contracts within the bridge components by means of international and limited international competition have been signed so far:

· GEOLOGICAL INVESTIGATIONS (joint-venture "CONEX" d.o.o - Mostar and "YERALTI ARMACILIK" - Istanbul),

· DESIGN, PHOTOGRAMMETRY AND CALCULATIONS FOR THE OLD BRIDGE ("GENERAL ENGINEERING" s.r.l., Italy)

· LABORATORY TESTS (LGA-Geotechnical Institute, Nuremberg).

· REHABILITATION OF “TARA AND HALEBIJA” TOWERS – ARCHITECT AND ARCHEOLOGICAL ASSIGNMENT (Omega Engineering, Grasa - Croatia)

· TECHNICAL CONSULTANT FOR PCU (BCEOM - France)

· CUTTING "TENELIJA" STONE STORED IN "KOMOS" (COMPANY "KARA-DRVO" – BiH )

· SUPERVISOR FOR CUTTING "TENELIJA" STONE STORED IN "KOMOS"   (Mr. ANTE KRŠINIC - Croatia)

· GEOLOGICAL INVESTIGATION (INSTITITE FOR GEOLOGY SARAJEVO – BiH )

· FONDATIONS OF THE OLD BRIDGE IN MOSTAR (YAPI MERKEZI - Turkey)

· RECONSTRUCTION OF THE OLD BRIDGE (ER-BU - Turkey)

· SUPERVISION OF THE RECONSTRUCTION OF THE OLD BRIDGE (Omega Engineering - Croatia)




Design objectives


This Pilot Project has been named, in agreement with PCU as "Rehabilitation of the Old Bridge of Mostar" since it is partially composed by different practical approaches: conservation and preservation, remedial and repair interventions, dismantling and remounting operations and reconstruction works. All the above should be aimed at the final rehabilitation and restoring of the Monumental Complex of the Stari Most (Old Bridge) of Mostar.



Main design assumptions:

§ The Bridge of Mostar has been totally destroyed and doesn’t exist anymore as a whole structure, its ruins are the only left portions that should be considered the real and the only original Old Bridge of Mostar.

§ The recovered stones are, at the moment, the only valuable elements of a great ancient monument, they have historical value, and they represent an interesting example of the ancient technique of assembling voussoirs and a constructive method which should be studied and investigated.

§ Some bridge stones and arch voussoirs have been recovered from the river and stored on a platform. Recovered stones, which are apparently not broken and which original position has been determined, are 9% of the global amount.

§ Some bridge stones and arch voussoirs are still built-in next to the former bridge springers. Those built-in stones, which are apparently not broken, are 13% of the global amount.

§ Abutment walls are, by now, damaged either by structural fractures, either by heavy and light shootings, and by small surface degradations due to time.

§ Something, with the war, has been definitely lost and may not be recovered or restored.


Main design interventions:

§ Recovered bridge stones and arch voussoirs, being what is left of the Old Bridge of Mostar should not reused, but should be preserved exactly as they are and kept in good condition to ensure their long lasting. This due either to restoration, either to structural requirements (since the reuse would have caused a new stone cut and a disassembling of the voussoirs).

§ Recovered bridge stones and arch voussoirs may be settled in a purpose built museum and they may be organised for exhibition purposes. The original Old Bridge would be therefore represented by those ruined portions, and this intervention would totally match the International Principles of Restoration: it guarantees complete safeguarding and preservation of the ruins and moreover it would be reversible and absolutely not invasive.

§ Recovered huge blocks of assembled voussoirs, that could not be settled on the platform due to their weight, should be moved in a museum as well as all the other recovered stones, to avoid their quick deterioration due to the river waters. (This despite ICE wanted these blocks to be left as a monument by the shore).

§ On the spot where the bridge was, following the willing of the citizen of Mostar and for social, political and symbolical reasons a “new old bridge” may be rebuilt as a declared copy of the previous one. This copy should be built not approximately or just close to the original one, since the value and the meaning of the new structure should be in the "philological" and historical research of the ancient monument as if this were an integration or a preliminary introduction to the visit of the real Old Bridge settled in the museum.

§ Remaining built-in bridge stones and arch voussoirs next to the springers and to the abutments, should be partially dismantled, during the remedial works, and remounted in the original locations, during the reconstruction works trough an anastilosis technique. This dismantling is required only to match structural and safety requirements.

§ Strengthening of the abutment walls next to the bridge springers should be performed before and while dismantling operation are ongoing.

§ Declaration between former bridge elements and new intervention should be performed trough refined and light marking devices, (as defined by design specifications and drawings).

§ Ancient abutments should be repaired only for what concern structural fractures and heavy shootings: only for those damages that, due to the river floods, may lead to further degradation if not repaired.

§ In the adjacent areas, concrete blocks should be totally demolished and remedial works should be performed over the ancient flooring.

§ Repair works should be performed leaving all the signs of time and small traces of the war, avoiding any intervention that may lead to a polished and renewed masonry layout.


Rehabilitation of the old bridge is therefore designed as:

§ conservation and preservation of the ancient stones recovered from the river;

§ remedial and repair of built-in stones, bridge remnants, abutment walls and flooring;

§ dismantling and remounting in the original locations of some portions of the bridge remnants;

§ reconstruction of a "new old bridge" marked and declared as a recent intervention;

§ demolishing of the concrete provisional blocks built during the war and post-war period;



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News


· On 25.06.2002, the Project Manager of the PCU announced the official beginning of the Works for the Contractor: the ER-BU Company. The works on the Project Documentation, Methodology Procedures and other documents are in preparations. Works on the Site started: the soil was firmed, drainage pipes for Radobolja River were repaired and reinstalled, condition of the roads was improved, fencing of the area started. Also the first scaffolding for the repair of the walls was erected.

· On 05.07.2002. Onega Engineering, signed the Contract for the Supervision of the Reconstruction of The Old Bridge. They situated in new office, provided and equipped by the Contractor – ER-BU.


CREDITS:

This NEWSLETTER was made in accordance with prevailing articles of the Contract No 002/2002 about the Rehabilitation of the Old Bridge, by ER-BU CONSTRUCTION / TURKEY

Paragraph concerning the destruction event and paragraphs concearning the design objectives are extracted from final architectural report - General Engineering

Intellectual property of final architectural report and of design drawings is owned by General Engineering s.r.l.
author of the text: arch. Manfredo Romeo – other contributes have been mentioned in related paragraphs
© - General Engineering Workgroup -

SOURCE:

Final Design Report  - General Engineering

ER-BU CONSTRUCTION / TURKEY

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