Four lawsuits filed on behalf of victims of last year's Amtrak-truck collision in northern Nevada claim railroad crossing gates either came down late or not at all.

The children of an Amtrak conductor killed in the June 2011 crash and three injured passengers filed the suits Thursday in Washoe District Court.

The Reno Gazette-Journal reports (http://on.rgj.com/LGrvZt ) the complaints allege the railroad companies used a defective rail crossing warning system and the Nevada Department of Transportation failed to post effective warning signs for motorists.

An Amtrak spokesman declined to comment. An NDOT spokeswoman says her agency had not yet seen the suit.

Trucker Lawrence Valli skidded and crashed into Amtrak's westbound California Zephyr east of Reno. Valli, conductor Laurette Lee and four passengers died, and some 100 people were injured.