1. The modulus of rupture (MOR) at groundline of wooden transmission poles

2. The extent and location of internal decay/defects in creosote treated poles.

Another aim of this paper is to demonstrate that techniques could be developed to carry out the above two tasks in a few minutes of inspection time for economic reasons.

Several configuration for ultrasonic propagation, eg. radial, tangential, diagonal and surface were used to predict the MOR at groundline. Energy absorption techniques were also used to predict strength. Good predictions of MOR for poles were made by using multiple regression analysis on some of the above techniques. For salt treated poles a combination of surface waves and the energy absorption technique were used to predict the MOR. Best predictions of MOR for creosote treated poles were made by using diagonal configurations. Good predictions of MOR for creosote treated poles were also obtained using radial and tangential configurations for ultrasound propagation. Different techniques were used for salt treated and creosote treated poles, due to their differing decay characteristics.

A series of experiments were performed to estimate the extent and location of internal decay in creosote treated poles. An algorithm was developed to generate a cross-sectional image of internal decay. The change in ultrasonic apparent velocity and attenuation was used to detect and locate the decay.

It is believed that the methods of strength prediction and decay detection presented in this report will give better reliability on assessing the strength and condition of poles. The inspection methods suggested can also compete on an inspection time basis with current techniques of pole inspection.