Paraic Ryan (Ireland) 1; Lara Hawchar (Ireland) 1; Mark Stewart (Australia) 2
1 - Department of Civil and Environmental Engineering, University College Cork, Ireland; 2 - Centre for Infrastructure Performance and Reliability, The University of Newcastle, Australia
According to the latest IPCC report, global warming may lead to increased risk of breakdown of infrastructure networks due to extreme weather events. Power pole networks represent important, and indeed valuable, critical infrastructure assets. There are approximately two million timber power poles in service in Ireland, five million in Australia, worth over $10 billion, and approximately 200 million in the US. Despite the scale and value of these critical assets, to date, little or no research has been conducted in Europe to examine their vulnerability to climate change. For instance, in Ireland, climate projections predict an increase in the activity and intensity of extreme storm events in winter. Thus, there is potential for increased risks of pole failure from extreme wind loads and falling trees, with significant direct and indirect cost implications. The work herein aims to quantify potential changes in power pole network risk and vulnerability using detailed probabilistic modelling and power industry collaboration. The climate-related hazards of interest are storm winds and timber decay – both of which may worsen due to climate change.
The climate change risk is assessed using a Monte-Carlo event-based sequential model, which incorporates structural reliability, deterioration, climactic effects and network maintenance. A full probabilistic analysis is performed to incorporate all uncertainties associated with climate change projections, material properties and loading. The results are presented in the context of a national network of one million Irish power poles.
The time-variant reliability analysis of the power poles is presented under various RCP trajectories as defined by IPCC. For each assessment, the numbers of wind failures and replacements due to pole condemnation is compared with the no-climate-change scenario results. This approach facilitates quantification of the potential impacts of climate change on a vital component of critical infrastructure. Two different locations are considered in Ireland in order to give some insight into spatial variability of impacts. Finally, advice is given regarding the efficient adaptation strategies that could be utilised by electricity infrastructure stakeholders.
This work shows that Irish timber power poles are vulnerable to future changes in climate. The time-variant reliability of the network is affected by a combination of increased deterioration (due to changes in temperature and rainfall) and changes in structural wind loading and resultant pole failure probability. The framework presented in the study can be applied to a range of critical infrastructure types, in any country.