There is a special ritual associated with the idols of Lord Jagannatha. Since the idols are made of wood, it needs to be replaced. The replacing doesn’t happen in a random fashion. It is done once every 9 to 10 years. There is a specific ritual associated with the replacement of the idols. It is called the Nabakalebara ritual. The literal translation is being a new body. The last time the ritual was done was in 2020.
Mind you, the idols are not made of just any wood. Neem wood is used for this and not just any neem wood. Apparently, the neem tree has to fulfill certain criteria, like it has to have x number of branches, colour and even the location of the tree is significant. Even the sourcing of the tree is a journey, it’s called the Banajag Yatra. An army of priests, helpers and carpenters go on the journey to find the right tree.
Once the new idols are created the old ones are buried in a secret ceremony. The Govt of Odisha declares a power cut when the ritual of burying the old deities is carried out. Legend has it that the person witnessing the ritual dies. Even when the new idols are placed in the temple, the ritual of transferring the energies from the old idol to the new is shrouded in secrecy, even the priest performing the ritual is blindfolded. The significance of the old and the new idols stand for destruction and reincarnation. An age-old Hindu belief.
The three mammoth chariots meant to take the idols around during the festival are made in a very detailed yet public process. It’s done in front of the royal palace, it is said that one family of carpenters have been carrying on the task of building the chariots for generations.