(a) The department shall have the authority to bring actions; and it may be sued in such actions as are permitted by law. In addition, the department may adjust and make settlement of any and all claims presented to it under oath.

(b) All actions brought ex contractu by or against the department shall be brought in a county where any part of the work is to be or has been performed. All other actions by or against the department shall be brought in the county in which the cause of action arose. Service upon the department shall be sufficient by serving a second original process issued from the county where the action is filed upon the commissioner personally or by leaving a copy of the same in the office of the commissioner in the Department of Transportation Building, Atlanta, Georgia.