WASHINGTON, May 14 (Reuters) - U.S. auto safety

regulators said Tuesday they have opened an investigation into

the performance of Alphabet's Waymo self-driving

vehicles after reports of its robotaxis exhibiting driving

behavior that potentially violated traffic safety laws.

The National Highway Traffic Safety Administration said its

preliminary evaluation into an estimated 444 Waymo vehicles

follows 22 reports of 22 incidents including 17 collisions.

The agency said in some of those cases the automated driving

systems "appeared to disobey traffic safety control devices" and

some crashes occurred shortly after the automated driving

systems "exhibited unexpected behavior near traffic safety

control devices."