Answer: 120
Explanation: According to the clause provided in the traffic rule, an operator approaching an intersection may proceed even while the stop traffic sign is still on based on certain traffic conditions or guidelines which includes : The operator must have brought the vehicle to a complete stop at the intersection for at least 120 seconds. After this minimum stop time, the operator may then proceed albeit taking great caution. That is, it must be safe to proceed at the time, if it's not safe, then the operator is expected to remain at the intersection.