Statue of Unity: Engineering, Construction and Project Management of World’s Tallest Statue
Boodovaa reached out to Prof. Devanshu Pandit to find out the history and construction facts about Statue of Unity, the world’s tallest statue in memory of Sardar Patel “Iron Man of India”, opened today on October 31st, 2018.
On the birth anniversary of late Vallabhbhai Patel (31 October 1875 to 15 December 1950), first home minister and deputy prime minister of independent India, world’s tallest statue will be unveiled by Prime Minister of India Mr. Narendra Modi. It is named as Statue of Unity to give tribute to eminent politician and statesman popularly known as Sardar Patel for his task of uniting 565 princely states of India.
At 182 metre height, Statue of Unity is now tallest statue anywhere in the world. It is almost double the height of Statue of Liberty. The Statue of Unity Project also encompasses other elements such as museum, exhibition and convention centre, and valley of flowers. The statue depicts Sardar with his characteristic garb in walking position. Sculptor Ram Sutar and son Anil Sutar has conceptualized the statue which was later molded in bronze panels exceeding 6,500 numbers. Prototypes up to 30 metre height were prepared before finalizing the moulding details. Panels have been fixed on structural steel space frame which is in turn supported on two cylindrical RCC core walls having 450 to 850 mm thickness. RCC core wall also house high speed elevators that take passengers to chest level viewing gallery having capacity of 200 persons.
Project is brainchild of Mr. Narendra Modi, Prime Minister of India, who was Chairman of Sardar Vallabhbhai Patel Rashtriya Ekta Trust (SVPRET) governing council which is special purpose vehicle created for the project. The Sardar Sarovar Narmada Nigam Ltd, a wholly owned Government of Gujarat undertaking has been given task to oversee the implementation of project. SSNNL appointed Turner Consultants (August 2012) as project management consultants to take the project further. It was decided to float the project as EPC project, meaning design, procurement and construction will be carried out by single agency. Larsen & Toubro Limited, an Indian company known for its excellence in engineering construction and project management was selected as EPC contractor (October 2014). Project cost for the main statue as per contract is Rs. 2332 Crores (350 million US dollars at 2014 exchange rates). For proof checking of designs EGIS-Tata Consulting Engineers joint venture were selected (August 2015). In all more than 30 consultants were hired by PMC, Proof Consultants and EPC Contractor for various services. At peak of the project almost 3000 people were working to finish project in stipulated 48 months completion period.
If you see the photographs of the Sadhu Island prior to commencement of project, you would not risk constructing a single story structure there. Soil investigations revealed presence of weathered rocks that are fractured. After excavating to required depth, pressure grouting was carried out to fill the cracks. Raft foundation having 3.5 metre depth was laid on which 67,000 metric tons of entire statue and structure weight rests. The foundation is surrounded by 20 metre wide retaining wall.
Tall structures like Statue of Unity are designed for Gravity, Wind, Earthquake, Hydrodynamic, Drift and combination of forces. One of the most important loads on tall structures is wind load. The winds can topple the structure entirely or damage the panels. It is quite difficult to model the wind effect for the Statue as compared to any regular shaped chimney or silo structure of similar height as human body is heavy in the middle whereas at legs it is thin. To understand wind effect on this uneven shaped structure, specially designed wind tunnel tests were carried out by RWDI who have expertise related to testing tall buildings. Structure is designed for a wind speed of 60 mps. Designs were carried out considering iconic structure with code+1 provision meaning the project is designed for earthquake zone-IV against zone-III applicable at site. The Statue of Unity is designed to resist earthquakes measuring up to 6.5 on the Richter Scale, at a depth of 10 km and within a radius of 12 km of the statue as mentioned by designer. Also hydrodynamic model testing was carried out since the statue lies in the downstream of the 135 mtr. high Sardar Sarovar Dam.
For understanding survey works Terrestrial LiDAR (Light Detection and Ranging) was used which proved to be precise and easy that helped with foundation and earthwork. Also satellite images were used for survey appropriately; conventional methods would have taken more time.
Construction of two elliptical core walls was main structure which had insert plates to support structural space frames. Bronze panels forming statue were fixed on space frame. Use of RCC core wall is quite common in tall building construction. Core wall thickness varied from 850 mm to 450 mm. The construction of core walls was carried out using Perry Jump Formwork with estimated time cycle of 7 days per lift. However in the initial days the time cycle was as high as 20 days, which got improved, with each lift probably due to learning curve effect. This would be an interesting case study for project management professionals.
The logistics for the materials and manpower were quite challenging due to constrained working space. To understand the project scale and logistics read these numbers:
- 210,000 cu.m. of cement concrete
- 18,500 tonnes of reinforcement steel
- 6,500 tonnes of structural steel
- 1,700 tonnes of bronze
- 1,850 tonnes of bronze cladding made up of some 565 macro & 6,000 micro panels
Statue of Unity, world’s tallest statue as on October 2018 has come out as an engineering marvel successfully executed with numerous construction challenges will be a case study for engineering, construction and management. While, it is going to be a popular tourist destination it will be an interesting structure to visit by engineers and architects.
GoG (2018), Official Video Documentary on Construction of Statue of Unity, Government of Gujarat.
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RWDI (2018) https://rwdi.com/en_ca/people/cini-anoop
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