One of the workers, an 18-year-old man from Three Hills, died at the crash site near Beiseker on Monday.
The other worker, a 19-year-old woman, also from Three Hills, was taken to hospital with critical injuries and remains in intensive care.
Mounties say the transport truck went through a stop sign and struck a car.
The truck and car next slammed into a parked pickup truck, then all three vehicles veered into the two workers standing nearby.
The truck driver, a 35-year-old man from Blackfalds, faces charges of dangerous driving causing death and dangerous driving causing bodily harm.
No names have been released.
Alberta Transportation Minister Ric McIver said in a statement Tuesday that the workers were employees of Carillion Canada, which was on contract with the provincial government.
They were "part of the team helping to maintain Alberta roads for the safety and benefit of all motorists," McIver said. "Our hearts go out to their families and friends during this time."
He said Alberta Occupational Health and Safety and the federal Transportation Safety Board are investigating. Alberta Transportation officials are also reviewing the crash.