An official at the Federal Railroad Administration says the agency inspected the area where a commuter train derailed and collided with another in Connecticut last week just two days before the accident.
The official also said a more detailed inspection using Sperry Rail Service technology was conducted in April. Neither recorded any defects.
More than 70 people were injured in Friday's accident just outside of Bridgeport, and rail service in the area was disrupted for several days.
Full service was restored Wednesday morning.
The National Transportation Safety Board has said it is looking at two sections of rail found at the crash scene which appear to have broken apart, to determine if the damage occurred during or before the crash.