The Missouri State Highway Patrol is investigating a crash killing a Springfield man on I-44 in Laclede County. Troopers report a tractor-trailer driven by 58-year-old Tipton J. McCurley of Eucha Oklahoma hit 36-year-old Cullen May, who was walking along the westbound lane of the interstate at mile marker 143 east of Lebanon at 7:16 pm Thursday. Troopers are investigating why May was on the interstate. Troopers shut down one lane of the westbound traffic to investigate.