(Corrects first name of train engineer in 10th paragraph, Brandon instead of Brian)
May 19 (Reuters) - A conductor critically injured in last week's deadly Philadelphia train derailment has sued Amtrak, his lawyer said on Tuesday, adding to a string of emerging lawsuits since the crash last week.
Emilio Fonseca, 33, was taking a restroom break in the first car during his work shift when the passenger train went off the rails, attorney Bruce Nagel told a news conference, saying the train suddenly surged forward and then crashed.
Fonseca, who is married and lives in Kearney, New Jersey, suffered a broken neck, back and both shoulders, and was believed to be the most severely injured Amtrak employee, Nagel said. He is among five people who remain in critical condition and is expected to remain hospitalized for several weeks.
Eight people died and more than 200 others were injured.
Fonseca is the second employee of the passenger rail line to sue over the crash, filing the action in state court in Newark claiming negligence and asking for unspecified damages, his lawyer said.
Other lawsuits have been filed by an Amtrak employee who was riding as a passenger and by four passengers who filed their action in federal court in Philadelphia.
Nearly a week after the derailment, it remains a mystery what caused the train to accelerate from 70 miles per hour (113 km per hour) to 106 mph (171 kph) in the minute before the crash. Authorities have not yet ruled out equipment malfunction, human error or other possible reasons for the train gaining speed so rapidly.
"There was a sudden surge and then the wreck occurred," Nagel said his client told him.
Crawling through the wreckage to a field, the badly wounded Fonseca immediately began warning injured and stunned riders to avoid stepping on downed electrified wires.
Train engineer Brandon Bostian, 32, who suffered a concussion, told investigators he has no memory of what occurred after the train pulled out of the North Philadelphia station, just before the crash.
The National Transportation Safety Board is investigating. (Reporting by Barbara Goldberg; Editing by Laila Kearney)