The answer shall specifically admit or deny the matter or set forth in detail the reasons why the answering party cannot truthfully admit or deny the matter. A denial shall fairly meet the substance of the requested admission. When good faith requires that a party qualify an answer or deny only a part of the matter as to which an admission is requested, the party shall specify the portion that is true and qualify or deny the remainder. An answering party may not give lack of information or knowledge as a reason for failure to admit or deny, unless the party states that he or she has made reasonable inquiry and that the information known or readily available to him or her is insufficient to enable him or her to admit or deny. A party who considers that a matter as to which an admission has been requested presents a genuine issue for hearing may not, on that ground alone, object to the request but may deny the matter or set forth reasons why the party cannot admit or deny it. The party who has requested an admission may move to determine the sufficiency of the answer or objection thereto in accordance with § 511.36 . If the Presiding Officer determines that an answer does not comply with the requirements of this section, he or she may order that the matter be deemed admitted or that an amended answer be served.
49 C.F.R. §511.34