Original sentence: "  During those same four years, Amtrak also failed to install and activate ATC on the northbound track at this curve, even though it had been installed and active on the southbound track, which could have avoided the incident even in the absence of the PTC system.Officials later said that the incident could also have been prevented by the installation of an existing simpler and cheaper system, ATC (Automatic Train Control), which had been operational for years on the southbound track of the curve at which the derailment occurred, but not on the northbound track.Shortly after the derailment, Amtrak completed that ATC installation on the northbound track
Edited sentence: "  During those same four years, Amtrak also failed to install and activate the ATC (Automatic Train Control) system on the northbound track at this curve, even though it had been installed and active on the southbound track, which could have avoided the incident even in the absence of the PTC system.And within days of the derailment, Amtrak had completed that ATC installation on the northbound track, apparently with none of the regulatory-requirement delays attributed to PTC.But officials later admitted that the incident could also have been prevented by the activation of an existing simpler and cheaper system, ATC (Automatic Train Control), which had been operational for years on the southbound track of the curve at which the derailment occurred, but not on the northbound track