Mourners dressed in black slept overnight on thin plastic mats on pavements near the Grand Palace in the Thai capital in order to secure a good view of the procession, which was expected to begin at 7 a.m. (1200 GMT).
The king’s cremation will feature ancient rites and a series of processions winding from the Grand Palace in Bangkok’s historic quarter to the 50-metre (165-feet) high Royal Crematorium that has been erected in a square near the palace.
His body will be pulled from the Grand Palace to the cremation site on a golden chariot. A sum of $90 million has been set aside for the funeral, the likes of which has never been seen in Thailand, officials in preparations have said.
King Bhumibol, also known as King Rama IX, died last October aged 88 after ruling for seven decades. He played a pivotal role in maintaining stability during years of political upheaval and rapid development.
Piyamat Potsopho, 38, said she had been waiting for the king’s funeral procession since Wednesday night.
“I was very fortunate to have been born under the reign of King Rama IX,” she said.
Another Bangkok resident, Suchinda Samparp, 67, said: “It’s so hard to describe the dedication I’ve seen, how people have come out to help each other and how the late king has inspired this.”
Analysts say the king’s death has left a large vacuum in the Thai psyche.
Thailand has observed a year of mourning for King Bhumibol and radio and television stations have played songs dedicated to the monarch almost non-stop since his death.
The songs urge Thais to follow in “father’s footsteps”.
King Bhumibol is often referred to as “father” by Thais and is credited with reviving the popularity of the monarchy in Thailand.
Days of heavy rain failed to deter mourners, many of whom pitched tents in order to gain the best access to the funeral.
Many businesses around the Southeast Asian nation were shut, while Bangkok’s old quarter was draped in floral garlands made of marigolds early. Some government buildings placed potted yellow marigolds around portraits of the late king.
King Bhumibol was born on a Monday, a day which Thais associate with the colour yellow.
Thai Buddhists traditionally keep the bodies of their dead for seven days before a cremation. Funerals of Thai royals, however, have historically taken place months after death.