Positive train control (PTC) automatically slows or even halts trains that are moving too fast or heading into a danger zone. Under current law, the rail industry must adopt the technology by year end.

The cause of Tuesday’s crash, in which seven people were killed, has only begun to be investigated. Regulators are examining whether excessive speed led to the derailment on an Amtrak line in Philadelphia, said officials familiar with the investigation.

Amtrak has begun installing components of a PTC system but the network is not yet functioning, federal officials said.

An Amtrak official did not immediately respond to a call for comment.