A lawyer filing suit over a fatal Amtrak crash near Philadelphia blamed a “colossal miscommunication” for the deaths of two rail workers killed when a train traveling 106 mph struck a backhoe on the same track.

Lawyers filed a negligence lawsuit June 2 on behalf of the family of one victim, 61-year-old Joe Neal Carter Jr. The Wilmington, Delaware, man was working overtime on a Sunday morning and operating the backhoe when the Amtrak train struck him.

“How could the operator of a scheduled train traveling at 106 mph not know of work being performed on the same tracks ahead?” lawyer Robert Mongeluzzi asked after filing the lawsuit in Philadelphia Common Pleas Court.

The precise cause of the April 3 crash remains under investigation by the National Transportation Safety Board. However, Mongeluzzi said he hoped to determine how “a colossal miscommunication … killed two men.” The other person killed was Carter’s supervisor, 59-year-old Peter Adamovich of Lincoln University, Pennsylvania.

Mongeluzzi, along with fellow Philadelphia attorney Thomas Kline, represent Carter’s two adult children in the negligence lawsuit. They also represent 34 victims of the May 2015 Amtrak derailment that killed eight people and injured more than 200.

In that derailment, the speeding train jumped the tracks on a sharp curve shortly after leaving Philadelphia for New York. The NTSB concluded last month that the engineer was distracted by word that a nearby commuter train had been hit by a rock. The agency also said a contributing factor was the railroad industry’s decades-long failure to fully install positive train control, GPS-based technology that can automatically slow trains that are going over the speed limit.

Mongeluzzi and Kline believe similar safety systems could have averted the April crash just south of Philadelphia that killed the rail workers.

“Ten deaths in 10 1/2 months on Amtrak’s rails in Philadelphia alone,” Mongeluzzi said at a June 2 news conference. “How many more will it take before Amtrak wakes up and realizes that safety starts at the top and safety on the rails affects both employees and passengers?”

Amtrak spokeswoman Christina Leeds said the company cannot comment on pending litigation.

The southbound train was heading from New York to Savannah, Georgia, when it struck the backhoe in Chester at about 8 a.m. The impact derailed the lead engine of the train, which was carrying more than 300 passengers and seven crew members. More than 40 people were hospitalized, most with minor injuries.

The train engineer had just five seconds to brake after seeing something up ahead on the track, investigators have said. The Federal Railway Administration has suggested the crash followed a breakdown in communications and issued a directive ordering Amtrak to retrain rail workers on basic safety rules.

Carter had worked for Amtrak for 40 years. Kline said he “lived his life on the rails and, unfortunately, lost his life” there as well.

The suit was filed by his daughter Montia Carter, of Richmond, Virginia