Investigators of Tuesday's deadly Amtrak derailment say they are focusing on reports that the train was traveling more than twice the 50-mile-an-hour speed limit when it entered a sharp curve in Frankford.
An automatic train control system designed to prevent speeding was not in place where Amtrak Train 188 crashed, killing seven people and injuring more than 200.
The train's engineer, who has not been identified, declined to give a statement to police investigators and left the East Detectives Division with an attorney, police commissioner Charles H. Ramsey said Wednesday.
The train's conductor, also unidentified, was at Einstein Hospital with a skull fracture, Ramsey said.
The train reportedly was traveling over 100 m.p.h. when it entered the curve, according to people close to the investigation.
The train's "black box," which includes a speed recorder, has been recovered by investigators.
Amtrak crews have been installing "Advanced Civil Speed Enforcement" on the Northeast Corridor and other Amtrak rail routes, and were to install the system this year in the Philadelphia area.
The system is designed to prevent collisions, automatically slow speeding trains and enforce speed restrictions.
Positive Train Control, which includes Amtrak's system, is required by federal law to be installed on all passenger and major freight railroads by the end of this year.
But many railroads have asked for more time to install the expensive systems, and Congress is considering extending the deadline to 2020.
The accident happened at a sharp curve in Frankford where several rail lines merge, and trains are restricted to 50 miles per hour there.