CTA rail cars have generally been secure and safe but in addition to general security issues on the CTA, there were calls to improve CTA's emergency response and communications procedures. CTA has also had incidents where operators apparently overrode automatic train stops on red signals, such as the 1977 collision at Wabash and Lake, when four cars of a Lake-Dan Ryan train fell from the elevated structure, killing 11, two minor incidents in 2001, and two more in 2008, the more serious involving a Green Line train that derailed and straddled the split in the elevated structure at the 59th Street junction between the Ashland and East 63rd Street branches, and a minor one near 95th Street on the Red line. In 2014, the O'Hare station train crash occurred when a Blue Line train overran a bumper at the airport station and ascended up an escalator.