Traditionally, the compilation of long-term timetables for high-density rail service with multiple classes of trains on the same track is a job for expert people, not computers. We propose an algorithm that uses the range-constriction search technique to schedule the timing and pass-through relations of trains smoothly and efficiently. The program determines how the timing of certain trains constrains the timing of others, finds possible time regions and pass-through relations and then evaluates the efficiency of train movement for each pass-through relation.