the ntsb has a go-team on the ground. they just spoke in the last half hour. take a listen. >> we're going to look at all of the signals, tracks, mechanics. there are many factors and human factor. that's part of the interviewing. as well as looking at the operations bulletins and some of the records to find out what exactly was the speed environment. and the requirements for this area. >> reporter: there's been a lot of talk about that positive access control system that would have automatically stopped this train here. that was not implemented at the time. we're told that it was likely going to be put in place next year on this particular track. right now, you can see that work is underway to remove the cars from this stretch of southbound i-5, that is going to be a massive process. cranes have been brought in and semi trucks to remove those cars. this is a major artery between seattle and portland. right now, it's completely shut down and they're working to