Pending its investigation and the decision thereon, the Arkansas Department of Transportation by written order at any time before the new rate becomes effective may suspend the operation of the rate. However, the suspension shall not be for a longer period than nine (9) months beyond the time when the rate would otherwise go into effect. Any order initially suspending the rate shall set a specific date for the commencement of a hearing inquiring into the rate requested unless waived by the applicant utility.