The National Transportation Safety Board determines that the probable cause of this accident was the failure of the Illinois Central crewmembers to operate IC Train 1218 at a speed so as to be able to avoid the collision.
Additional factors that contributed to the occurrence of the accident were:
- The failure of the Illinois Central crew-members to comply with the rule requiring that a crewman take a conspicuous position on the lead car and display a white light when cars are pushed by an engine.
- The failure of the Illinois Central Railroad Company to provide additional protection to accommodate the safe movement of trains on track No. 6 when track changes initiated a permanent display of "Restricted Proceed" on signal 6-1799 in 1969.
- Inadequacies in operating rules, practices, and personnel training.
Contributing to the severity of the accident was the apparent lack of clash protection provided to the occupants of the IHB locomotive.