Catherine Stouffer, the wife of 37-year-old Gary Stouffer Jr., seeks unspecified damages in the suit filed Thursday in Dallas.
It's the second lawsuit filed since a train traveling 62 mph in November struck a flatbed truck that was part of a Midland parade honoring wounded vets and their wives.
Among the suit's assertions is that Union Pacific was negligent for failing to maintain a safe crossing.
Raquel Espinoza, a Union Pacific spokeswoman, expressed sympathy to the family but said in a statement that investigators confirmed the crossing signals worked properly at the time.
The National Transportation Safety Board is investigating.