MADISON, Wis. — A Memorial Day parade that led to a traffic jam blocking railroad tracks in a Milwaukee suburb did not amount to a specific hazard that could make the railroad company liable for striking a minivan, the Wisconsin Supreme Court ruled Tuesday. The decision was seen as a victory for the railroad industry, which worried that an opposite ruling could lead to railroads being liable for negligence for not slowing down under a variety of scenarios. Federal law requires trains to slow down or stop in …