A serious affair was occurred us in September 1999. This was an accident of a timber bridge giving way in the park, Ehime prefecture. This bridge was constructed 10 years ago and made of Ekki(Lophia alata Banks ex Gaertn.) . Ekki is one of the trees which evaluated as having considerable endurance against the decay without a chemical treatment. But it was clear to occar a lot of internal dicay by some fungi from investigation of it.

We had another affair in this time. This was to evaluate for two bridges of same type in this park. Because we thought that two bridges might be had some potential of same internal decay of a timber bridge giving way. Therefore we investigated to decide most convenient non-destructive commercial equipment using a timber bridge giving way at first. As this result, We selected PUNDIT (Portable Ultrasonic Non-destructive Digital Indicating Tester in full) for evaluation of two bridges. It shows specifications of PUNDIT in table 1. PUNDIT utilizes an ultrasonic pulse generator to impart a stress wave into the member of the timber bridge. Two transducers are placed a fixed distance apart on a member. When the transmitting transducer imparts a wave into a member, PUNDIT timer is started timing passage of the wave. This timer is stopped and displayed the transit time in microseconds when the wave is reached the receiving transducer. We made decay maps from these measurements.