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

regulators said on 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."

Waymo did not immediately respond to a request for comment.

This is the latest in a series of investigations opened by NHTSA

into performance of self-driving vehicles after initiated probes

into General Motors Cruise and Amazon.com's ( AMZN ) Zoox .

In February, Waymo recalled 444 self-driving vehicles after

two minor collisions in quick succession in Arizona, saying a

software error could result in automated vehicles inaccurately

predicting the movement of a towed vehicle.

NHTSA said all 22 incidents included either self-driving

crashes or driverless vehicles that exhibited driving behavior

that potentially violated traffic safety laws.

The incidents include collisions with stationary and

semi-stationary objects such as gates and chains and collisions

with parked vehicles.

NHTSA also cited incidents "such as vehicles driving in

opposing lanes with nearby oncoming traffic or entering

construction zones."

The auto safety agency will investigate the Waymo 5th

Generation automated driving system performance "in the

incidents identified in this resume and similar scenarios, as

well as to more closely assess any commonalities in these

incidents."

The investigation, which is the first stage before the

agency could demand a recall if it believes the vehicles pose an

unreasonable risk to safety, will evaluate Waymo vehicles

performance "in detecting and responding to traffic control

devices and in avoiding collisions with stationary and

semi-stationary objects and vehicles."

Waymo said in March it was beginning to offer free

driverless robotaxi services to select members of the public in

Los Angeles after receiving approval from a state agency to

start its ride-hailing program, Waymo One, in Los Angeles and

some cities near San Francisco.