Nowadays, many passengers rely on transfer guidance systems and their demands for punctuality of trains have become very high. In order to satisfy passengers' requirements for punctuality, it is necessary to establish an approach that can help deternining where delays occur and the type of delay reduction measures to be taken to reduce delays most efficiently. We have established functions to acquire and record the departure and arrival times of all trains in seconds at all stations. Based on these data, we introduce two indices that will be useful in deternining the places where delay reduction measures should be taken and the most effective delay reduction measures. We have applied this approach to the Hanzomon line, which is one of the most congested lines and small delays occur frequently. The results indicate that the proposed approach considerably reduced delays.