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Transcript of Restoration works carried out on the historical Mehmed...
Restoration works carried out on the historical
Mehmed Pasha Sokolovic Bridge across the
River Drina in Bosnia and Herzegovina
Halide Sert, Süheyla Yılmaz, Mutluhan Nas, Hakan Demirci, Ayşe Avşin,
G. Sibel Turan, Nurdan Apaydın
Ministry of Transport, Maritime Affairs and Communications, General Directorate of Highways, Department of Structures, Division of Historical Bridges, Ankara, TURKEY.
Abstract Having witnessed the development of many civilizations for centuries,
Anatolia has been knitted all around with road networks from end to end in order
to meet the transportation-based needs of communities such as communications,
military, trading etc. Within the process, the bridges that are a part of the transport
system have become a complementary part of the cultural history over time as
useful structures serving in terms of the commercial, economic, military, social
and cultural issues. This study reports the restoration project and application
studies conducted under the technical counseling and supervision of the General
Directorate of Highways between 2009 and 2016 on the Historical Mehmed Pasha
Sokolovic Bridge crossing over the river Drina within the boundaries of Republika
Srpska/Bosnia and Herzegovina and included in the World Heritage List in 2007,
and this study is believed to contribute to the restoration discipline requiring the
cooperation of different professional groups.
1 Introduction
In addition to constructing new roads and bridges, improving the existing
historical bridges through maintenance and repair is also among the primary duties
of the General Directorate of Highways. According to the Division of Historical
Bridges' Inventory (as of December 2015), there are a total of 1816 bridges at
home, including stone bridges (1721), wooden bridges (29), iron bridges (32) and
reinforced concrete bridges (34), and a total of 308 bridges abroad, including
(121) in Bosnia and Herzegovina, (25) in Greece, (11) in Kosovo, (2) in Croatia,
(42) in Serbia-Montenegro-Sandzak, (20) in Macedonia, (3) in Lebanon, (18) in
Albania, (26) in Bulgaria, (1) in Palestine, (4) in Iraq, (2) in Romania, (1) in
Hungary, (1) in T.R.N.C, (4) in Syria, (3) in Crimea, (1) in Saudi Arabia and (23)
in Egypt, which were built during the rule of Ottoman Empire.
2
2 Routes in the Balkans during the Ottoman Period
As an outpost of the Ottoman Empire, the Balkans had always a strategic
importance for Istanbul, that served as the Empire's capital as of 1453, and acted
as a technology, information and communication bridge between the Ottoman
Empire and the Europe. Due to this strategic importance of the Balkans, the routes
connecting Anatolia to the Balkans and to the inner Europe has always maintained
its importance. These paths were composed of three main routes, including the
Right, Center and Left Arm departing from Istanbul, and secondary road
connected to these main routes and these three routes connected the Empire to
Crimea via the Right Arm, to Vienna over Belgrade via the Center Arm and to
Athens over Thessaloniki via the Left Arm. Thanks to the road system developed
by the Ottomans in Rumelia, both the cities were supported in economic and
military terms and, thanks to this road system, the end centers were also developed
rapidly. The best example in this regard is that Sarajevo, which was an end center
before, turned into a major trading center with the settlement of population and
still maintains its viability with its three extant covered bazaars and downtown.
The Center Arm which was heavily used in the active trading activities between
the Empire and the Europe during the Ottoman Period and also served as the main
route followed by the army during the expeditions launched from time to time
between Istanbul and Belgrade, was also intensely used by the messengers and
thus both the road and the bases on the road were always kept well-maintained
(Halaçoğlu, 2002; İnalcık, 2010).
3 Ottoman Bridges in Bosnia and Herzegovina
Within the borders of Bosnia and Herzegovina where the majority of Ottoman
bridges in the Balkans are located, only a total of 100 bridges, 32 of which are
non-extant today, have been duly identified so far although a total of 121 historical
bridges were reported to exist there before. Therefore, it would be reasonable to
attribute the main reason why those bridges were so destroyed to the fact that the
bridges in the region were blasted during the World War I, II as well as the Civil
War in the region between the years 1992 and 1995. Among these bridges located
in the Bosnia and Herzegovina are also the bridges built by Mimar Sinan which
marked the Classical Ottoman Architecture during the 16th
century. After being
appointed as the "Imperial Chief Architect", "Sinan the Architect" played a
leading role in the design and application of the architectural masterpieces
symbolizing the power of the Empire and built a total of 9 bridges within the
borders of Turkey and 3 bridges outside our borders (Bektaş, C.,1968).This paper
reports the restoration project and application studies carried out on the historical
Mehmed Pasha Sokolovic Bridge over the river Drina which is located on the
route providing access to the Adriatic Sea over Sarajevo and Dubrovnik by
departing, in Nis and Constanta, from the middle route connecting Istanbul to
Belgrade and reached today thanks to the repairs performed on it in different
periods despite particularly the devastating effects caused by wars.
3
4 Historical Mehmed Pasha Sokolovic Bridge
4.1 Location, History and Architectural Features of the Bridge
Crossing over the river Drina in the city center of Visegrad within the borders
of Republika Srpska/Bosnia and Herzegovina, the bridge is 1070 km far from
Istanbul and 130 km from the capital, Sarajevo (Figure 1). The bridge was built by
Mimar Sinan, the Imperial Chief Architect, between the years 1571 and 1577 at
the behest of the grand vizier Mehmet Pasha Sokolovic who was born in the
village of Sokolovic (Sokol) near Visegrad. According to foundation charter of
1574: “The founder of the Foundation (Mehmet Pasha, Sokolovic, son of the
martyr Sinan Bey) has had a high and twelve-arched stone bridge built over the
river known as Drin (Drina) beside the town of Veşgırad (Visegrad) in the
starboard of Bosnia in Rumelia and devoted it to the passers-bys', passengers' and
other people's service… Also, in order to preserve the bridge and other charity
works, the endower has devoted a great deal of real properties for bringing in
money and ensuring their repair and maintenance; in return for this, may the name
of the endower be remembered with gratitude by people and all these good deeds
done by the endower be written in the books of deeds forever….” [VGM (General
Directorate of Foundations) Archive, Reg. No: 572].
Figure 1. Mehmed Pasha Sokolovic Bridge over the river Drina.
The L-shaped bridge has a total length of 228,60 m, including 179,40 m over
the river bed and 49,20 m as the ascending ramp, and a total width of 7,25 m. The
bridge which has a total of 12 arches, including 11 under the part crossing over the
river and 1 under the ascending & descending ramp, has 3 more arches under its
part where the ramp is connected to the road. The abutments (flood splitters) were
built in a triangular form in the upstream side and of in a circular form in the
downstream side. The sofa is located opposite the richly decorated stela situated
Downstream, 2007
Sarajevo
Istanbul
4
on the abutment A6 in the upstream side and there, there are two inscriptions on
the construction of the bridge stating that the bridge was built at the behest of
Mehmed Pasha Sokolovic between 1571 and 1577.
On the spandrel walls, there are niches and palmettes and a rosette on the
spandrel wall situated on the bending side of the bridge. What put the bridge on
the map today is the novel 'The Bridge on the Drina' which describes, by the
testimony of the bridge, the last 350 years of the relationship between different
ethnic cultures living in the region and brought the Nobel Prize in Literature to its
author Ivo Andrić in 1961.
4.2 Pre-Restoration State of the Bridge
With the effect of the dams constructed in the downstream side of the bridge in
1966 and in the upstream side in 1989, the irregularities in the river bed have
gradually increased and the problems in the foundations and abutments of the
bridge have got bigger. After being indicated among the 100 endangered sites in
the world by the "World Monuments Watch" in 2005, the bridge was included in
the World's Cultural Heritage List by UNESCO in 2007. In order for the
elimination of damages on the bridge and the execution of restoration works by
Turkey, a cooperation protocol was signed between TIKA on behalf of Turkey
and the Commission to Preserve National Monuments, the Ministry of Education
and Culture of the Republika Srpska and the Municipality of Visegrad on behalf
of Bosnia and Herzegovina on April 19,.2010. In addition, another protocol was
signed between TIKA and the General Directorate of Highways on March 5, 2008
in terms of the Supervision Services for the Restoration Project and on December
8, 2011 in terms of the Supervision Services for the Restoration Application.
4.3 Restoration Application Projects
Technical Research Studies; Prior to the restoration works, Dzemal Bijedic
University of Mostar carried out technical research studies on the bridge from
2007 to 2008, and in this scope, topographic measurements were made on the
river bed, core samples were collected from (11 points on) the bridge through both
mechanical methods and drilling and thus the geological and geotechnical
investigations describing the bridge's body, foundations and the ground on which
the bridge is located were performed, and, thanks to the original samples, the
physical, chemical and mechanical properties of the new materials to be used in
restoration were identified. In conclusion of these studies, it was seen that the
foundations of 4 abutments situated in the side facing Sarajevo were settled on a
solid rock whereas other abutments were settled on a poor and a very poor rock
and the foundations with a height ranging from 1.30 m to 4.20 m and given the
form of an encasement were constructed on a pine-type wooden grid system
5
1 2 3 4 5
6
7 8 9 10
consisting of 2 or 3 rows. It was determined that the original mortar used in the
abutments other than those numbered A3, A4, A5 and A6 which were
reconstructed between 1949 and 1952 and filled internally with cement mortar
was the lime mortar containing stone chips and powder, and the stone used there
was krečnjak (a limestone as hard as marble) whereas it was sedra (a hollowed-
type limestone) in the abutments, arches, spandrel walls, cornices and parapets.
Measured Drawings; All surfaces of the bridge, the measuring works of
which were started on 18.11.2008, were scanned with laser and a 3-D model of the
bridge was obtained. It was also found out that, due to the changes occurred in the
water level and flow rate of the river Drina following the construction of the
Bajina Bašta Dam in the downstream side of the bridge and the Visegrad Dam in
its upstream side, the river bed profile has undergone some changes in places and
the foundations have substantially come out into the open. As a result of the
structural analyses, it was observed that there occurred significant tensile stresses
in the bridges' foundations which were exposed to both its own weight and
hydraulic loads. As a result of technical researches conducted on the bridge and
the river bed, the bridge's construction system as well as the current status of the
relations between ground-foundation-river were identified and the measured
drawings were prepared in line with these data (Figure 2,3).
Figure 2. Upstream Facade, Measured Drawing
Figure 3. Scouring in the Abutment A3, Perspective View and Structural Analysis
Restitution Projects; In order to identify the bridge's state when it was first
built and the changes it underwent in the time; all historical researches, foundation
certificate-charters, archive data, previous projects, old photographs, engravings
285
.92
A
3
Top encasement level of the Abutment A3: 285,92
Abutment A3
Abutment A3
Top
encasement
level of the
Abutment
A3: 285,92
Thalweg
level of the
Abutment
A3: 283.66
283
,66 Thalweg level of the Abutment A3: 283.66
Hydraulic load analysis of the current status:
Max. tensile strength: 1,05 MPa
6
and traces on the bridge were investigated. Based on the archival studies
conducted in the Prime Minister's Ottoman Archives, it was determined from the
documents dated 1854 and 1865 that the several correspondences were exchanged
for the repair of damage in the bridge's abutments and for requesting an allowance
in this regard, and that the bridge was repaired in 1873, however fully submerged
during the great flood in 1896.
It is also stated by the resources that the inscriptions heavily damaged during
the World War I and brought to the State Museum of Sarajevo in 1928 were
reconstructed by the museum and the same inscriptions completely destroyed
along with the richly decorated stela during the World War II were restored
through repairs in 1949/52 and 1977/79 (Mujezinović, M., 1953). Besides, the
bridges built by Mimar Sinan were typologically analyzed and the bridges built in
Europe in the same century were also examined in this context, and all repairs
undergone by the bridge so far were analyzed in line with the documents and
information obtained as a result of large-scale researches. It was also found out
that the foundations of the bridge which was heavily damaged during the World
War I and II (Figure 4,5) and reconstructed along with its five arches and
abutments, underwent a thorough repair between 1980 and 1982 and a concrete
injection was performed to the foundations of the abutments A5, A6 and A8
(Gojković,M.,1989).
Figure 4. After World War I, 1915. Figure 5. After World War II,1943. Despite some changes resulting from the repairs performed in different
periods, it was observed that the bridge has maintained its original architectural
and structural properties. As a result of the evaluation of all these documents and
information, a restitution project was prepared for the bridge's possible state in the
period when it was first built.
Restoration Application Projects were prepared in accordance with the
principle of minimum intervention on the basis of maintaining the bridge's original
construction system and material properties, uniforming the water flow through
amendments to the river bed and thus improving the bridge’s resistance against
natural conditions and time by individuating the environmental conditions as far
as possible (Figure 6). In this context, it was envisaged to provide a stone support
as a raft foundation in a way to also cover the foundations outcropped, to take out
the secondary elements on the bridge floor, to re-construct the stone cladding, to
repair the damaged parts and the three-arch bridge in the ramp section and to
7
ensure the lighting of the bridge along with landscaping. The Restoration
Application Projects were approved by the General Directorate of Highways and
TIKA on 26.10.2009, by Institute for Protection of Cultural, Historical and
Natural Heritage of Republika Srpska on 07.04.2010 and by the Commission to
Preserve National Monuments of Bosnia and Herzegovina on 17.06.2010. Upon
receipt of the building permit from the Ministry of Landscaping, Construction and
Ecology/Bosnia and Herzegovina, the tender for the Restoration Application
Works was held under the coordinatorship of TIKA in Bosnia and Herzegovina on
December 12, 2012. The Restoration Application Works were actually started on
April 1, 2013 in accordance with the work schedule and with the preparation of
the stones to be used in the stone support as a raft foundation projected to be built
on the riverbed.
Figure 6. Layout Plan and Upstream Facade, Restoration Project.
Mehmed Pasha Sokolovic Bridge
(L:179,40 m)
Three-Arch Bridge
(L:30m)
Linking Road
(L:81m)
Ramp Section
(L:49,20m)
Protected Area’s Boundary
K
8
4.4 Restoration Application Works
Before the restoration works, joint meetings were held with the officials of
Visegrad and Bajina Bašta Dams in the upstream and downstream of the bridge,
and it was aimed to ensure minimum water level from September 1 to October 1
taking into account the electricity generation and ecological balance and to
complete the anticipated works in the riverbed within this period. It was
determined from the topographic surveys of 01.09.2013 on the riverbed and
encasements that scouring in the thalweg line was still continuing, and the
scouring was minimum(1,90 m.) in the upstream side of the abutments A8 and A9
and maximum in the downstream side of the abutments A3, A4, A5 and A6.
Accordingly, the top level of the stone support to be built as a raft foundation was
determined to be 285.92, which is top encasement level of the original abutment
A3. The stone support projected as a raft foundation was built as about 18m long
in the upstream and 24m long in the downstream side and, on the river shore, until
starting point of the solid ground in according with the project levels(Fig 3,7,8).
Figure 7,8 . Constr. of stone support as a raft foundation/Install. of scaffolding.
The earth fill on the cornice level, involving the ramp (49,20 m), linking road
(81 m) and three-arch bridge(30 m), and the sediments amassed by the running
water were carefully scoured, cleaned and subsequently, the remnants of a wall
(12 m) belonging to an ancient road network under the ground of the three-arch
bridge were reached and the necessary revisions were made to the project . Then,
the impaired stones on the spandrel wall's surface were decomposed and then
completed, the stones deviating from the vertical direction were numbered,
removed and then brought to the plummet and used in original places (Fig 6,9,10)
Figure 9,10. Excavation/Decomposition-Removal Works.
Downstream, 2013 Downstream, 2013
A2
A3
A1
A1
9
The fouling on the stone surfaces of the spandrel wall, especially on the
abutments and inside the arches, were removed using a low pressure (1.5 bar)
water and soft plastic brush without damaging the patina and joints (Figure 11).
Figure 11,12. Cleaning Works / Joint Opening and Pointing
In order to fill the structural gaps under the spring line of the arches,
foundations and other sections under the water, a 30% ready-mixed mortar was
added to the original mortar mixture ratio and a low pressure injection was
applied. The damaged and disappeared joints between the original abutments,
arches, spandrel walls, wing walls and parapet stones were renovated using lime-
based mortars prepared in accordance with the original mixture ratio .In 2014, the
non-original cubic stone flooring on the cornice line over the riverbed was
removed and replaced by a flat flooring made of krečnjak stone and this was also
applied on to the bridge's sections over the ramp and the three-arched bridge. In
2015, however, the top levels of the stone support built as a raft foundation on the
riverbed were removed and, after checking their suitability for the project, the
necessary corrections were applied and, following the completion of the remaining
works, the cubic stones dismantled from the bridge deck were used in the parking
lot between the linking road and the main road and in the landscaping works in
Visegrad, and also the lighting system of the bridge was installed.It is planned to
complete, in 2016, the landscaping works in the immediate vicinity of the bridge,
all the planned manufacturing of which was achieved within the Restoration
Application Project, and to put the bridge into service in May 2016 (Fig. 12,13,14)
Figure 13,14. View of the bridge after restoration works.
Downstream, 2016 Downstream, 2016
10
5 Conclusion
Having meticulously executed the Project and Application works within the
historical KONJIC Bridge's restoration thanks to the experiences it gained from
technical counseling services given during the reconstruction of the historical
MOSTAR Bridge, our General Directorate takes the same great care to the
Restoration Project and Application works of the historical MEHMED PASHA
SOKOLOVIC BRIDGE. In conclusion, the Bridges ensuring the continuity of the
transportation system by providing a seamless gateway service during the
commerce, communication, pilgrimage, migration and excursion and "bringing the
past to the present" by reflecting the architectural and engineering know-how of
the period will survive thanks to the restoration work carried out by the General
Directorate of Highways despite the destructive effect caused by people and
natural conditions and continue to be useful structures serving the social and
cultural issues.
References
1. Batur, A, Batur, S (1968) Works by Sinan, C. BEKTAŞ, on behalf of Koca Sinan Association,
Sinan Committee (Published by Sinan Committee for the 380th Death Anniversary), Doğuş
Printing House-1567, İstanbul; 63-92.
2 Çulpan, C (1975) Turkish Stone Bridges, Turkish Historical Society Publications, Ankara.
3.Erdoğan,M. (1988) Strategic Importance of the Works by Mimar Sinan within the Military
Bodies of the State, VGM Publications, İstanbul.
4.Gojković, M (1989) Stari kameni mostovi (Old Stone Bridges), Naučna knjiga.
5.Halaçoğlu,Y. (2002) Transport and Communication in the Ottoman Empire, General
Directorate of PTT, Ankara.
6.İnalcik, H. and Ari,B. (2010), Turkish Islamic and Ottoman Urbanism, Proceedings Book of
Turkish World and Cities Board -III, s.57-70, 24-27 May 2010, Astana.
7.KGM (2007) History Highways, Turkish Road Association Publications, Ankara.
8.KGM (2013) Division of Historical Bridges Inventory, KGM Archive, Ankara.
9.KGM, TİKA (2009) Sokollu Mehmet Paşa Bridge Construct. Drawing and Rest., Unpublished
Tech. Report, KGM Archive, Archive Reg. No: BIH / VİSEGRAD / N.86 / RUP-2009, Ankara.
10.Ortayli, İ (2007) Turkey Organizational and Administrative History, Cedit Publica., Ankara.
11. Sert, H et al. (2009) Historical Bridges' Technical Specifications, Legislations, Inventories,
Projects, Maintenance and Repair, KGM Publication No:268, KGM Publishing House, Ankara.
12. Sert, H et al. (2012) Historical Bridges' Technical Specifications, Legislations, Inventories,
Projects, Maintenance and Repair, KGM Publications, KGM Publishing House, Ankara.
13. Sert, H (2012) Restoration Works Conducted on the Ottoman Bridges in BIH, Hist. Mostar,
Mehmed Pasha Sokolovic and Konjic Bridges, Turkish World Engineering, Architecture and
Urban Plann. Conf., Proceed. Book, s.151-168, 15-18 Ekim 2012, Trabzon.
14. Sert, H, (2013), Restoration Project and Application Works Conducted on the historical
Mehmed Pasha Sokolovic Bridge crossing over the river Drina in Bosnia and Herzegovina, 4th
Symposium on Strengthening of Historical Structures and Their Safe Transfer to the Future,
TMMOB Chamber of Civil Engineers, İstanbul Office, İTÜ, İstanbul.
15.VGM Archive, Reg. No: 572.
Note: The unacknowledged photos used in this paper were taken from the archive of the General
Directorate of Highways, Division of Historical Bridges.