Can I sue the person that caused my accident while I was in my mail truck doing my route?
Yes, you can sue the person who caused the accident in court. That is a civil case separate from your federal workers’ compensation case.
If you obtain a recovery in your civil case, by federal statute, OWCP can claw out money from your recovery or settlement. This is called a right of subrogation.
NOTE: The above are general statements. Every case is different. Seek legal help based on the unique facts of your case.