Iowa Code § 434.11: Additional rules and regulations.

The rules, regulations, method, and requirements herein provided to be made by the director of revenue shall be made and communicated in writing or print to the said several railway companies and shall be and become binding upon said railway companies as provided in chapter 17A, provided, however, that the director shall have the power to prescribe supplemental or additional rules, regulations, and requirements in the manner prescribed by chapter 17A.