The State has a duty to use ordinary care to keep its property reasonably safe for the benefit of those who come upon its property as invitees. (Peters v. State (1984), 36 Ill. Ct. Cl. 255). The State has a duty to its invitees to warn them of hazardous conditions not readily apparent. Nolan v. State (1983), 36 Ill. Ct. Cl. 194; Ross v. State (1971), 27 Ill. Ct. Cl. 104; Kelly v. State (1969), 26 Ill. Ct. Cl. 426. For the Claimant to establish a breach of the heretofore stated duties, the Claimant must prove by a preponderance of the evidence that a dangerous condition existed, that the State had actual or constructive notice of the dangerous condition, and that the State's negligence was the proximate cause of the Claimant's injury. Perlman v. State (1979), 33 Ill. Ct. Cl. 28; Mackowiak v. State (1982), 35 Ill. Ct. Cl. 315. Comparative negligence is to be applied in such cases. (Peters, supra.) a claimant is held responsible for all normal, obvious and ordinary risks at the time in question. (Fleischer v. State (1983), 35 Ill. Ct. Cl. 799; Duble v. State (1967), 26 Ill. Ct. Cl. 87). A legal duty requires more than the possibility of occurrence and the State, like any other person, is charged with a duty only when harm is legally foreseeable. The issues of foreseeability and duty involve a myriad of factors, including the magnitude of the risk involved, the burden of requiring the State to guard against the risk, and the consequences of placing such a burden on the State. Wilson v. State (1989), 41 Ill. Ct. Cl. 50; Owens v. State (1989), 41 Ill. Ct. Cl. 109.