RULE 28. SIDE AND LAP BACK TRIPS.  When an engineer is required to make an emergency side or lap back trip  between his terminals, miles made will be added to the mileage of the regular trip, and paid for on continuous time basis. Such side or lap back trips when not made in emergency, will be paid as per Rule 24, with a minimum of one hundred (100) miles for eight (8) hours or less (straight-away or turnaround), time consumed in such trips to be deducted when computing time on regular road trip.