Trooper Kyle Deatherage, 32, was struck by the truck-tractor near milepost 62. He was pronounced dead at the scene.
"Trooper Deatherage left a legacy of courage and duty and today he is surrounded by the respect of his fellow officers and by the love of his friends and family. Our hearts are heavy with grief, but they are also strengthened by Trooper Deatherage's brave calling," Illinois State Police Director Hiram Grau said in a statement.
Deatherage has been a member of the Illinois State Police since 2009. He is survived by his wife, Sarah, and two young children.