helps. it would have prevented this accident the ntsb said very bluntsly. because if person didn't slow down the train, the ptc would. why wouldn't it be in place on such a major stretch of track? >> i think the short answer is money and time. these systems are very expensive to put in. they're very complex to build. the technology is certainly there. but actually developing and installing it is taking a long time for amtrak and also for commuter railroads and for freight railroads across the country. but amtrak, you know, has been telling a lot of people for a long time that they will make the deadline. which is december 31st of this year to have all of their networks outfitted with this technology. but if you look closely it no longer really looks like that. they say they have done about 400 miles of track with ptc and they have about 1200 to go. it just doesn't look like they will make it on time.