One of the news reports said the signalling system had not been completed- sounds like false economy!

http://www.bloomberg.com/video/spain-s-high-speed-train-disaster-on-the-scene-QbZFjUXkQEO13dVeMINL~Q.html

http://www.bloomberg.com/news/2013-07-26/spanish-probe-into-rail-crash-focuses-on-speed.html