The extent of premature failure among treated wooden utility poles in Uganda

Abstract

Eucalypts spp and eucalyptus hybrids such as Grandis x camadulensis & Grandis x utrophylla clones are the species used for electricity transmission lines in Uganda despite being very susceptible to termite attack and degradation by other biodegrading agents. In this study, premature failure of wooden utility poles in service in Uganda was assessed. The objectives were to (i) quantify the extent of premature pole failure in terms of the number of poles failing per year and the proportion of the total poles supplied for the last five years (ii) quantify the extent of premature pole failure in terms of monetary losses per year for the last five years and (iii) assess the cause and point of failure of poles failing prematurely with respect to geographic and specific location of the poles in service in Uganda. The methods used in this study were (i) secondary data obtained through review of relevant documents such as annual performance reports, audited financial statements among others (ii) a total of thirty-eight key informants i.e. twenty two from eleven ERA licensed wooden utility pole suppliers and sixteen from government agencies dealing with utility poles. These were selected and interviewed so as to obtain information on quantity of pole failure vis-a-vis the quantity of poles supplied (iii) focus group discussions were held with major players in the wooden poles industry in Uganda. (iv) two hundred thirty-one failed poles were sampled from four regions in Uganda through a snowball sampling method, and observations made on causes of each pole failure, point of failure, hazard class of the poles, and geographic location of the poles in service. A total of 83,605 of the 1,007,290 poles supplied in the last five years failed prematurely and this accounted for Ugshs. 30,913,673,440 incurred in their replacements over the same period. Fungal decay (53%) and termite damage (21%) were the leading causes of pole failure while bird nesting (2%) and mechanical forces (2%) were the least. Seemingly dry areas presented the highest (88%) pole failure while private farms had the least (3%) observed wooden pole failure. Western Uganda (45%) had the highest pole failure while Northern Uganda (10%) had the least pole failures. Failure was highest (74%) at the bottom and least (1%) at the top. It was found out that on average, 16,721 poles i.e. 8.3% of treated wooden utility poles were replaced in the country annually over the last five years accounting for Ugshs. 6,182,734,688 incurred on their replacements annually. There was an association between hazard class, geographic location, point of pole failure and cause of pole failure. Fungal decay and termite attack were the main causes of premature failure of treated wooden utility poles and these mostly occurred at the bottom of the pole, around the ground line. The important factors for explaining pole failure in Uganda were; cause of pole failure, point of pole failure and geographic location of the pole in service. It is recommended that: (i) deliberate policy measures be instituted for purposes of ensuring that pole sourcing, handling, seasoning and preservative treatment is done according to set national standards so as to minimise premature pole failure and its associated costs; (ii) further research be conducted on (a) the effect of age, species, moisture content, drying defects at the time of treatment, physical and mechanical properties of seasoned poles on the final product (treated wooden utility poles) (b) quality of chemical and method used in treatment of wooden utility poles by pole treaters (c) effectiveness of the recent initiatives such as use of pole saver sleeves and concrete back filling.