In this appeal plaintiff contends that when the evidence she presented is viewed in the light most favorable to her, that evidence is sufficient to withstand a motion for directed verdict and to take the case to the jury on the question of McMahan’s and Moore’s negligence. We disagree.
As to defendant McMahan, plaintiff argues that a jury could find that he did not keep a reasonable lookout, drove faster than reasonable under the conditions, failed to keep his car in control, or failed to exercise reasonable care to avoid the collision. Under the facts and circumstances of the case, plaintiff’s argument is without merit. In McNair v. Boyette, 15 N.C. App. 69, 189 S.E. 2d 590 (1972), the Court held:
“When the facts are admitted or established, negligence is a question of law and the court must say whether it does or does not exist and this rule extends to the question of proximate cause.”
The facts clearly established at trial show that McMahan heeded the signs warning of a dangerous intersection. He even decreased his speed to beiow that recommended by the Highway Department. His speed was reasonable under the conditions. Further, he kept a reasonable lookout in that he took notice of the warning sign and saw the Archie car stopped at the intersection. The driver on the dominant road is entitled to assume until the *212last moment that a motorist on a servient road who is stopped in obedience to a stop sign will yield to him. Raper v. Byrum, 265 N.C. 269, 144 S.E. 2d 38 (1965). Finally, when the Archie car pulled into his path, McMahan took immediate action to try to avoid the collision. The facts clearly establish that McMahan acted in a reasonable manner and was not negligent.
As to defendant Moore, plaintiff argues the same failure to keep a reasonable lookout, failure to maintain a reasonable speed under the conditions, and failure to exercise reasonable care to avoid the collision. Moore’s failure to heed the warning sign and reduce his speed under the facts in this case would constitute sufficient evidence to go to the jury on the question of his negligence. Childers v. Seay, 270 N.C. 721, 155 S.E. 2d 259 (1967).
However, even though a jury might find Moore’s actions negligent, he would be liable only if his negligence were a proximate cause of the plaintiff’s injuries. 6 Strong, N. C. Index 2d, Negligence, § 10, p. 25. Where the facts are admitted or established, the existence of proximate cause is a question of law. McNair v. Boyette, supra. If Moore’s failure to heed the warning signs would have produced no injury except for the intervening act of another, his negligence would be insulated by the intervening act. The test by which the negligent conduct of one is to be insulated as a matter of law by the independent intervening act of another is the reasonable un-foreseeability on the part of the original actor of the subsequent intervening act and resultant injury. McNair v. Boyette, supra.
Moore, like McMahan, was entitled to assume that a motorist stopped on a servient street with clear visibility would obey the stop sign and yield the right of way. Raper v. Byrum, supra. The facts established that the Archie car traversed the northbound lane of Highway 49 and had turned into the southbound lane. Had defendant Archie not collided with McMahan and been knocked back into the northbound lane, her car would not have collided with defendant Moore’s. Archie’s conduct was not foreseeable, and except for that conduct and the presence of the McMahan car in the southbound lane, which plaintiff admits she did not see, the collision injuring the plaintiff would not have occurred. Archie’s conduct constituted an intervening act that insulated defendant Moore’s conduct from any causal connection with the injury.
*213The directed verdicts for defendants McMahan and Moore were proper. The judgment of the trial court is
Affirmed.
Judges Vaughn and Martin concur.