Together, they have been through thick and thin, trudging through the deep snow, camping in the wilderness and occasionally confronting wild animals living in the forests.
The area Chai oversees includes more than 50 base stations, the nearest 10 km from the company, and the farthest 400 km, which takes him eight or nine hours to reach.
Most of these stations are built on the top of mountains and cannot be reached by car. He has to climb the mountain tracks, sometimes as far as 4 km, carrying heavy equipment.
Apart from the long distances and arduous journeys, Chai also constantly faces danger from extreme weather and wildlife.
"During most of my trips, I cannot rest, because of the distance and the scarcity of people. Sometimes when I get too drowsy, I get out of the truck and wipe my face with snow, or turn the music up as loud as it can be to keep myself awake," he says.
"In the winter here, the sun sets after 3 o'clock. Once the sky gets dark, I cannot see the tracks clearly, and it gets even more dangerous."
The tracks in the forest region are particularly hazardous, Chai says. In winters, hot spring water freezes and collects on the roads, forming sheets of ice that can extend up to several kilometers and amass as high as several meters.
Drivers who let their guard down might think they are just flat, icy roads, not knowing that there is still running water underneath. Once the ice cracks, the cars will be trapped.
Chai cannot recall how many times he has been trapped on these roads. With no residents nearby and no signal to contact rescue, he has sometimes had to wait for as long as 10 hours overnight in temperatures below — 40 C.
Some of these hardships have lessened since the company equipped him with a satellite phone, but with improved ecological protection, he has been encountering all kinds of wild animals, including bears, wolves and lynxes.
"Once, I looked up and, just 4 meters away, I saw a black bear staring at me. I climbed up the nearest pine tree and waited for the rescue," Chai says.
"It is said that people experience a burst of energy when facing threats. As a result of that experience, I believe it, because, later, I tried to climb that same tree and couldn't."
Persevering with the job is not the result of yearning for adventure. In fact, growing up in Moridaga, he had been bored with the sight of trees and mountains, and longed to leave them to pursue a life in a big city.