RECENT PROJECTS - PERTH SUBURBS.
Western Power invited AVS to evaluate 100 pole structures in the Perth metropolitan region. In the sample, fifty percent of the poles were unserviceable and included poles from the same geographic area. Many of the poles, both unserviceable and serviceable, were previously reinforced with 'angle' or 'H' beam staking systems.
We have evaluated the structures using TMXScan, LSEPatrol® and Best® Engineering systems. Our methodology on this project exceeded normal inspection methods and includes our proven non destructive ground-line assessment and complex engineering computations to confirm the serviceability of the structures.
The sample size of this project is statistically
too small to derive any assumptions and strategies over the entire Western Power
asset base. It did however, provide an indication of the analysis that can be
undertaken on a wider scale and in turn provided some sound information for
strategic decision making. It should also be noted that it was not a true random
sample as it included a symmetrical (50/50) sample of asset conditions, and
therefore, does not model the profile of a distribution network.
We modeled the poles from 'as new' (designed) through to 'as inspected' to finally reinforced or refurbished. We observed:
| 1. Satisfactory design
application but a percentage of under engineering; 2. A degradation rate higher than comparable asset bases; 3. An asset life lower than accepted tolerances; 4. Low mean average across-line and along-line Sis presenting potential risk to the business; and 5. The benefits of reinforcement with the appropriate staking system. |
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The linear rate of decay of the asset sample is 2.45% per annum with an average structure life of 24.3 years. The expected life of an asset in this urban environment, as defined in AS 4676 [1] is 35 years. It should be noted however, that the potential inaccuracy of the structures' year installed date and existence of termites could distort the real asset life figures and the decay rates.
Our staking model highlighted the value of staking with a thirty-five percent serviceability increase over the entire asset sample. After reinforcement the mean serviceability index moved from 0.8 to 1.3. This model is the most accurate reflection of the samples actual condition in the field and presented a more manageable asset profile.
As previously mentioned this study could not be used to determine sound asset strategies for Western Power for the reasons given above. However, the use of the AVS system, apart from a non-destructive testing regime, could provided Western Power with the data analysis and subsequent asset study to determine:
1. Network degradation rates;
2. Accurate short and long term CAPEX forecasting;
3. Asset risk assessment;
4. Accurate (not adhoc) reinforcing programs;
5. Future inspection regime changes (inspection frequencies);
6. OPEX forecasting for structural reinstatement and inspection; and finally
7. The ability to assess the value of current processes and strategies.
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