(a) Computation. In computing any period of time, the day of the act, event, or default upon which the designated period of time begins to run is not included. The last day of the period is included unless it is Saturday, Sunday, or a legal holiday in the District of Columbia, in which event the period runs until the end of the next day which is not a Saturday, Sunday or holiday. This rule applies to forward and backward measurement of time.

(b) Extensions. Any time period, except those provided by law or specified in these rules respecting informal complaints seeking damage, may be extended by the Board in its discretion, upon request and for good cause. Requests for extensions must be served on all parties of record at the same time and by the same means as service is made on the Board. However, if service is made on the Board in person and personal service on other parties is not feasible, service on other parties should be made by first class or express mail. A request for an extension must be filed not less than 10 days before the due date, except that in cases seeking expedited relief for service emergencies under part 1146 of this chapter, a request for an extension must be made within 24 hours of service of the petition, reply, or other filing or procedural order of the Board as applicable. Only the original of the request and certificate of service need be filed with the Board. If granted, the party making the request should promptly notify all parties to the proceeding of the extension and so certify to the Board, except that this notification is not required in rulemaking proceedings.

(c) Exception to time computation rules. See 49 CFR part 1152 for special abandonment rules.