Karuppachamy Kalaimuragan (24) was busy guiding lorries in and out of the site in Changi area on Saturday evening when the tipper truck mowed him down, The Straits Times reported.
Though the cause of the accident is being ascertained, the Singapore daily cited other drivers at the site who said Karuppachamy was on the phone when the reversing vehicle hit him.
Karuppachamy was decapitated and his helmet was left half buried in the sand about a metre away from his twisted body, the media report cited the drivers as saying.
Preliminary findings show Karuppachamy might have been hit by the truck when he was giving directions to its driver.
Police and the Manpower Ministry were further investigating the incident.