49 CFR 511.18: Joinder of proceedings.

Two or more matters which have been scheduled for adjudicative proceedings, and which involve one or more common questions of law or fact, may be consolidated for the purpose of hearing, appeal or the Administrator's review. A motion for consolidation for the purpose of hearing may be filed with the Presiding Officer by any party to such proceedings not later than thirty (30) days prior to the hearing. A motion for consolidation for the purpose of appeal may be filed by any party to such proceedings within 10 days after issuance of the Initial Decision. A motion to consolidate shall be served upon all parties to all proceedings whose joinder is contemplated. The proceedings may be consolidated where to do so would tend to avoid unnecessary costs or delay. Such consolidation may also be ordered upon the initiative of the Presiding Officer or the Administrator, as appropriate. The Presiding Officer may order separate hearings on any issue where to do so would promote economy or convenience or would avoid prejudice to a party.