Union Pacific Railroad Co. will have to face a lawsuit alleging that its employee’s negligence caused a driver to crash into a train.In a written opinion and order, filed Friday, U.S. District Judge Iain D. Johnston of the Northern District of Illinois granted summary judgment to Union Pacific on a claim that it provided inadequate measures to prevent the crash.However, he wrote that Union Pacific was not entitled to summary judgment on a claim that one of its flagmen negligently directed the plaintiff to drive …