Case Study: Effect of Archaeological Excavation on Time and Cost in Historical Peninsula Construction WorksCemil Akçay
Throughout history, Istanbul has hosted several civilizations. The historical Peninsula, also known as Sur İçi, stands out in Istanbul because of its historical buildings and areas that have been inherited from past generations. The historical Peninsula is located within the borders of the Fatih district and the Yenikapı Filling area. In this region, hundreds of registered works are located and historical sites included in the UNESCO World Heritage list are also found. The region’s Urban-Historical sites constitute the vast majority of the region. Numerous examples of civic architecture were razed and sunk under the ground as the region, which was the capital of great civilizations such as the Roman, Byzantine, and Ottoman empires, changed hands due to wars. Therefore, archaeological research excavations are conducted under the Museum Directorate’s supervision to avoid damage to existing cultural elements during construction works in the region. When movable and immovable cultural assets are discovered during excavation, they are either are registered and protected or removed according to the decisions of the Cultural Heritage Preservation Board. Similarly, the region’s shoring system is constructed as a well foundation and excavations are performed as archaeological excavations. The use of archaeological excavation and well foundation shoring systems in the constructions on the historic Peninsula raises construction costs and extends the completion time. This study investigates the effects of archaeological excavation and well foundation construction on time and cost based on an outstanding project in the region. These effects were revealed by comparing the archaeological excavation of the same building in this region and construction with standard construction techniques in another region, in line with cost study, a business plan with critical path, and budgeting techniques with the S-curves.
Tarihi Yarımada İnşaat İşlerinde Arkeolojik Kazı İmalatlarının Süre ve Maliyete Etkisi: Vaka AnaliziCemil Akçay
İstanbul zaman içerisinde birçok medeniyete ev sahipliği yapmıştır. Geçmişten günümüze miras olarak gelen tarihî yapı ve alanlar düşünüldüğünde İstanbul’da Tarihi Yarımada bir diğer adıyla Sur İçi ön plana çıkmaktadır. Günümüzde Fatih ilçe sınırları içerisinde kalan bölge ile Yenikapı Dolgu Alanı’nın olduğu alan Tarihi Yarımada’yı oluşturmaktadır. Yüzlerce tescilli eserin bulunduğu bu bölgede ayrıca Unesco Dünya Miras listesine giren tarihî alanlar da bulunmaktadır. Bölgenin büyük çoğunluğu Kentsel-Tarihi sit alanıdır. Roma, Bizans ve Osmanlı İmparatorluğu gibi büyük medeniyetlere başkentlik yapmış olan bölgenin savaşlar neticesinde el değiştirmesi birçok sivil mimarlık örneği yapının yıkılması ve toprak altında kalmasına sebep olmuştur. Bu sebeple bölgede yürütülen inşaat işlerinde söz konusu kültür tabakalarına zarar verilmemesi için İstanbul Arkeoloji Müze Müdürlüğü denetiminde arkeolojik araştırma kazıları yapılmaktadır. Kazıda, taşınır ve taşınmaz kültür varlığına rastlanılması durumunda ilgili Kültür Varlıkları Koruma Bölge Kurul kararları doğrultusunda, kültür varlıklarının tescili ve korunması veya kaldırılması söz konusu olmaktadır. Yine, bölgede benzer şekilde iksa sistemi olarak kuyu temel iksa sistemi yapılmakta ve bunların kazıları da arkeolojik kazı olarak gerçekleştirilmektedir. Tarihi Yarımada’da gerçekleştirilen inşaatlarda uygulanan arkeolojik kazı ve kuyu temel iksa sistemleri, inşaat maliyetlerini arttırmakta ve inşaatların tamamlanma süresini uzatmaktadır. Bölgedeki örnek bir proje üzerinden yola çıkılarak hazırlanan bu çalışmada arkeolojik kazı ve kuyu temel imalatlarının süre ve maliyete etkisi incelenmiştir. Aynı yapının bu bölgede arkeolojik kazı ile yapılması ile başka bir bölgede normal inşaat teknikleriyle yapılması; maliyet çalışması, kritik yol ile iş planı yapılması ve S eğrileri ile bütçeleme yapılması teknikleri doğrultusunda kıyaslanarak söz konusu etkiler ortaya konulmuştur.
The historical Peninsula is the entire region that comprises the Fatih district and the Yenikapı Filling area and has hosted several different civilizations throughout history, such as Rome, Byzantine, and Ottoman. Istanbul, which is located on the historical Peninsula, has served as the capital of several empires including Rome, Byzantine, and the Ottoman. “Suriçi” is another name for the historical Peninsula. When studying the region’s history, the first ruins date back to prehistoric times, and the first formation of the topography dates back to 7000-8000 BC. It highlights the historical past extending back to the Roman and Byzantine empires and the Neolithic period within the purview of the Marmaray project, particularly boat remains and other archaeological findings in the excavations conducted in the Yenikapı station area. In addition, four areas in the region are designated as Historic Areas in the UNESCO World Heritage List: Sultanahmet Protection Area, Süleymaniye Mosque, Zeyrek Mosque and its surroundings, and Istanbul Land Walls. The region’s city history, e.g., Istanbul’s, bears the imprints of great civilizations. Besides wars, natural disasters such as fires and earthquakes have caused the destruction and burial of architectural and artistic structures. Therefore, not degrading existing cultural components and instead highlight them during construction activities in the region is essential. First and foremost, the Sultanahmet area in the historical Peninsula was classified as an “Archaeological Park” by the High Council of Real Estate Antiquities and Monuments in 1953. Then, in 1979, Zeyrek was designated as a “Protection Area.” In 1981, Süleymaniye Mosque and its environs were also registered as a “Protection Area.” The Cultural Heritage Preservation Regional Board registered and declared the entire region, encompassing the old Eminönü and Fatih district borders, as a protected area in 1985. Moreover, in line with the region’s development, renewal areas have been established under Law No. 5366 on the “Protection and Reconstruction of Deteriorated Historical and Cultural Immovable Assets” to reconstruct and restore the renovation areas and protected areas that have eroded and lost their characteristics. Due to the city’s development and the fact that existing unregistered buildings do not satisfy the earthquake regulations criteria in practice, it is now required to perform construction activities in the historical Peninsula and accelerate this process, like Istanbul. In addition to restoring existing registered works to their original state, unregistered buildings are renewed as part of a master plan in the renovation areas, in compliance with the Preservation Zoning Plans approved by the Cultural Heritage Preservation Boards. The Cultural Heritage Preservation Boards also assess the relationship between new or renovated and the registered buildings in the region. First, archaeological foundation research excavations are conducted in the historic Peninsula during the construction, under the supervision of the Archaeological Museums (assigned in line with the project approved by the board. A set of rules governs construction activities in the historic Peninsula. Conservation Zoning Plans approved by the Cultural Heritage Preservation Regional Boards govern construction in urban and historical sites. The region’s renewal areas are implemented according to the zoning plans and the preliminary island projects prepared by the relevant municipality and approved by the Regional Preservation Boards. Construction works in the region begin with archaeological research excavations supervised by the General Directorate of Istanbul Archaeological Museums. Construction works continue when no movable or immovable cultural property is found from the research excavations. If immovable cultural assets are located, surveys of the immovable properties are drawn up, and the Cultural Heritage Preservation Boards decide whether they will be preserved. Following the abovementioned decisions, it will be decided if the construction projects will be implemented or revised. The cost of undertaking construction work in the region has increased because of these projects. The construction period has also lengthened. Employers and contractors who will perform the job must plan ahead of time to account for this circumstance.
This study explores the effects of archaeological research excavations and well foundation constructions on the duration and cost of construction work in the historical Peninsula based on the building work planning methodologies. All construction work items are scheduled on a network based on the time and priority order. The duration of the project and the periods (abundance) in which a job can be delayed without delaying next works and the project total Critical Path Method (CPM), which is a network planning method, are utilized to calculate the start and end times of the work items using forward and backward mathematical calculations. In construction projects, the project’s total and time-dependent cost changes and the time-dependent changes of the resources used in the project are analyzed using the S-curves as a functional project control tool.
In this direction, an outstanding project has been handled, the majority of which is underground. Excavation and shoring-works up to the foundation level have been calculated with two alternatives in the project. In the first option, a well foundation shoring system was used for the archaeological research excavation. Bored pile and mechanized excavation productions are utilized in the second option, which will be employed if the construction is performed in a normal area outside this region. Construction work items, quantity, and cost analyses were conducted for both options. The network planning CPM method was adopted to calculate the construction time. The cumulative duration and costs of the two alternatives were compared with the S-curves drawn. The total cost of archaeological excavation and well foundation production was 58% more than bored pile and machine excavation in the case examined in the study. The study also shows that the time required for archaeological excavation and well foundation construction would be 113% more than bored pile and machine excavation.