Index: src/timetable_cmd.cpp
===================================================================
--- src/timetable_cmd.cpp	(revision 16577)
+++ src/timetable_cmd.cpp	(working copy)
@@ -233,6 +233,10 @@
 
 	v->lateness_counter -= (timetabled - time_taken);
 
+	/* Reset vehicle delay if it becomes larger than the duration of the timetable,
+	 * because then we are back in the normal timetable loop. */
+	v->lateness_counter %= v->orders.list->GetTimetableDurationIncomplete();
+
 	for (v = v->FirstShared(); v != NULL; v = v->NextShared()) {
 		InvalidateWindow(WC_VEHICLE_TIMETABLE, v->index);
 	}