A team of researchers controlled a drone to take pictures of the 56m-tall bell-shaped stupa of Wat Phra Mahathat Woramahawihan in Nakhon Si Thammarat. It slowly flew in a cycle from the base to the top of the golden spine while capturing the high-resolution images of the structure.
On the ground, another team erected 3D laser scanners to take pictures of the stupa and other structures on the temple grounds, including smaller stupas built around the grand stupa, an ordination hall, a prayer hall and museums. The aerial shots from the drone and pictures from the scanners would be combined to create an accurate 3D structure of the whole temple, covering a 34 rai plot of land.
While the two teams were busy with their work, another research group placed a set of equipment inside the prayer hall to measure natural vibrations. Later they climbed the roof of the hall to reach the base of the grand pagoda. They needed to measure the vibration on various spots around the principal stupa, or Phra Mahathat Chedi in Thai, to identify the natural force and factors that can lead to its instability.
"It is the first time that the stupa has been systematically examined with high technology by a team of academic researchers," said Asst Prof Chatchai Sukrakanchana, the chairman of Nakhon Si Thammarat Council of Cultural Affairs and the chair of the academic working group of world heritage committee of Nakhon Si Thammarat.
Digital images from the drone offer as high a resolution as 0.5mm in detail, allowing researchers to see if there are any cracks on the stupa. Jetjaras Na Ranong
"The result based on the engineering perspective will be deeper and more accurate than the visual inspection. The information will be crucial for developing a restoration plan required by the Unesco World Heritage Committee when we submit the nomination dossier by next January," he said.
Wat Phra Mahathat has been on the tentative list of the Unesco World Heritage sites since 2012. At that time, the government allocated about 600 million baht in the budget, which was spent on improving the temple facilities, including building a new 3km road from a train station to the temple, moving electrical wires around the temple to underground and restoring the stupa. At present, the committee is preparing required papers and trying to build public awareness about the World Heritage status. (See sidebar.)
"Phra Borommathat Chedi is an important sacred site of Theravada Buddhism in the southern peninsula. It is among the eight great relics among stupas in Thailand and is known as one of the important Buddhist pilgrimage sites in the Kingdom," he said.
Legend has it that the grand stupa of the temple was originally built in the 6th century by King Sri Dhammasokaraja I, the first ruler of Nakhon Si Thammarat, to house Buddha's tooth relics. In the early 13th century, his successor, King Sri Dhammasokaraja V, rebuilt the stupa in the present Lankan-style, which is the bell-shape stupa, surrounded by 158 small pagodas.
The bell-shaped stupa underwent many renovations, including the latest restoration last year by the Fine Arts Department. Today, the central stupa is white and the top is shining gold. The official ceremony to celebrate the complete restoration project was organised in February this year.
Around the middle of the year, the provincial committee invited the academic team from Bangkok to conduct the structural analysis. The team was comprised of lecturers and researchers from the Engineering Faculty of Thammasat University, the Engineering Faculty of King Mongkut's University of Technology Thonburi and the Faculty of Science of Kasetsart University.
The top of Phra Borommathat Chedi was made of real gold weighing 197.85kg in total. Jetjaras Na Ranong
They spent about one month in the field. Their research project is part of the ongoing Historic Site Restoration for the Foundation of Sustainable Conservation project, funded by Thailand Science Research and Innovation (TSRI), formally known as the Thailand Research Fund.
"TSRI has supported the project for sustainable conservation for three years," said Assoc Prof Chanathip Pharino, director for the Public Well-Being Division of TSRI. The project was first implemented in Ayutthaya Historical Park, where the research team applied engineering science and other related fields to create the database and 3D images of Wat Yai Chaimongkol and Wat Chai Wattanaram.
"Our project can help find out if the historic structures are in danger of collapsing by judging tilt angles so the restoration can be done in time," said team leader Assoc Prof Nakhorn Poovarodom from Thammasat University.
Nakhorn was interested in the conservation of historical sites in Ayutthaya in the early 2000s when he brought his Japanese guests to Wat Phra Si Sanphet in Ayutthaya. His guests expressed concern over the collapse of one structure which was once in good shape when they had last visited 20 years prior.
"The concern hit me. I knew that I must do something; otherwise, more ruins may be deteriorating with no one knowing it," he said.
Equipped with expertise in structural mechanics and structural dynamics, he brought his engineering students for a research field trip in Ayutthaya Historical Park. They tried to measure and record the sizes of some ruins with pen and paper.
During that period, when mobile phones were not yet smart and still with the black-and-white screen, and drone technology was out of reach, the field work was labour-intensive. Years passed by, and the progress was too slow. But he did not give up. A few years later, his effort paid off when TSRI funded his research with the support of the Fine Arts Department. Nakhorn formed the team with other academic lecturers and researchers from the three universities.
They worked on the conservation project in Ayutthaya for two years. Last month, the project won TSRI's Outstanding Research Awards. The team brought the knowledge and tools they applied in Ayutthaya to Nakhon Si Thammarat.
The experience helped shorten the research time. In Nakhon Si Thammarat, they spent about a month collecting data and analysing the strength of the principal pagoda and other buildings. The team found that the grand stupa was slightly leaning.
"The stupa is leaning at about 1.5 degrees to the south. The tilt started at the start of the cone shape while the foundation of the stupa is stable. So far the stupa can withstand the tilt and does not have a safety issue," he said.
The 3D laser scanners are placed at 130 stations inside the temple. Jetjaras Na Ranong
After gathering more data, they applied "Finite Element Analysis" to develop damage scenarios. They found that the stupa can withstand a maximum lean of 5 degrees. The top part of the pagoda will collapse if it leans at 7 degrees.
"No one knows when and why the stupa started leaning. It might have leaned during the early years right after it was built. One thing we know for sure is that it is still strong and safe," said Nakhorn.
The team is not yet done with the field research. The next step is to find out if there are any structures hidden underground or around the main pagoda, and this may help discover the cause of the leaning.
A geophysicist research team of Kasetsart University joined hands with the Fine Arts Department for the study. The team brought in ground-penetrating radar equipment for the surveying. The information can be integrated with the 3D images of the temple to help complete the digital database of the site.
"The digital database and 3D photos will bring huge benefit to the future restoration," said Phanuwat Ueasaman, head of the archaeological research team from the 12th Regional Office of the Fine Arts Department.
"Instead of relying on the 2D image of old photos, the 3D pictures can give us more details of the structure and architecture. The [Historic Site Restoration for the Foundation of Sustainable Conservation] project should be implemented in other historical sites."
Asst Prof Dr Passakorn Pananont, right, and his geophysicist research team from Kasetsart University demonstrate the ground-penetrating radar machine. The equipment can identify subjects up to 5m underground. Jetjaras Na Ranong
Campaign to get locals on side
"I think it is good. The World Heritage status will bring more tourists to our province," said Dej Somjit, 70, an imam of Chumchon Lang Wat, a community located behind the temple.
"I am not sure if it is a good idea. I am afraid that the temple will not allow us to open our shops if it achieves world recognition," said Arun Chaowanakul, 63, who lives in the community.
In addition to Wat Phra Mahathat in Nakhon Si Thammarat, four other cultural sites are on Unesco's tentative list. They are Monuments, Sites and Cultural Landscape of Chiang Mai, which has been on the tentative list since 2015; Phra That Phanom and its related historic buildings and associated landscape in Nakhon Phanom (2017); Ensemble of Phanom Rung, Muang Tam and Plai Bat Sanctuaries in Buri Ram (2019); and the Ancient Town of Si Thep in Phetchabun (2019).
Students performed a manora dance during the merit-making ceremony. Jetjaras Na Ranong
