In Lincoln County v. Edmond, 231 Ga. App. 871, 875 (2) (501 SE2d 38) (1998), county policy required the road superintendent to remove trees obstructing county roads or to provide warnings of the danger. Id. There was evidence that, for approximately two hours after being notified that a tree had fallen across a county road in a heavy rainstorm, the superintendent failed to take action to remove the tree or to warn the motoring public of the hazardous condition. Id. The Court held that the superintendent's duties were ministerial, even though he retained discretion in the manner by which he accomplished them, and that he could be held liable for breaching those duties. Id. The Court held that to invoke the waiver of sovereign immunity under the motor vehicle exception found in OCGA 33-24-51, a plaintiff "must prove that the defendant's action (misuse of a county vehicle) was both the cause in fact and the proximate cause of the injury." 231 Ga. App. at 873 (1). The plaintiff in that case alleged that a county employee had acted negligently when, after being informed of a downed tree, he drove his county truck back to the county garage, rather than proceeding to the scene of the downed tree. The Court rejected the argument that the ensuing accident arose out of the use (or misuse) of the county truck, thereby abrogating the county's sovereign immunity. Specifically, the Court held "that the non-use of a motor vehicle is not encompassed within the meaning of OCGA 33-24-51(a)," because "negligent use does not include the failure to use at all." Id. The Court further explained: Although plaintiff has fashioned a theory under which the county may be held liable, that theory must fail because the county truck assigned to the employee is only tangentially related to his failure to act, which is the true heart of plaintiff's complaint. Whether the employee's failure to act was negligent and the proximate cause of plaintiff's injuries would clearly be a jury question. But, equally clearly, the absent county truck was not used so as to be "both the cause in fact and proximate cause" of the injuries sustained by Edmond. Without such "use," plaintiff's suit against Lincoln County and the Board of Commissioners is barred by the doctrine of sovereign immunity. The trial court's denial of their motion for summary judgment was error. Id. at 873-874 (1).