Proceeding under article 78 of the Civil Practice Act to review a determination of the Commissioner of Motor Vehicles which revoked petitioner’s operator’s license upon a finding of gross negligence. There is evidence in the record to support a finding that petitioner was proceeding in his right-hand lane of a three-lane highway; that he suddenly and without signal turned to bis left as a tractor *713trailer was about to pass him in the center lane, causing a collision which resulted in another collision between the tractor trailer and a car proceeding in the opposite direction. Extensive property damage and personal injuries resulted. The Commissioner had adopted this version o£ the facts, and, as there is adequate evidence to support that version, we may not disturb the factual determination. It was also within the field of fact-finding to determine that such conduct was gross negligence. In modern traffic a left turn without adequate observation or warning is an extremely dangerous maneuver which would justify the trier of the facts in determining that it constituted gross negligence. Determination unanimously confirmed, without costs.