An initiative by the Department of Transport and Main Roads and ARRB

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ASSET MANAGEMENT – Accounting for life-cycle costing implications and network performance risks of rain and flood events

NACOE Project Number: A4

Contact email: info@nacoe.com.au

Project Stage of Completion: 100%

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Between 2010 and 2013, the Queensland road network was impacted by a series of major cyclone and rainfall events that caused $6.5 billion dollars of damage to the network. The Transport Network Reconstruction Program (TNRP) was established to facilitate the state-wide recovery of the state-controlled road network. This project sought to quantify the impact of these events in a life-cycle costing framework, and to identify the funding levels required to improve the resilience of the network as it responds to future events.

A series of case studies were developed that enabled a comparison of three investment scenarios; the base case of what actually happened, a full resilience scenario and a ‘stitch-in-time’ approach to road rehabilitation. A life-cycle costing model was developed to facilitate this analysis. The study found that large benefits can be realised through the full-resilience option, but that this requires a very high agency investment. In contrast, the stitch-in-time approach may not require increased total agency costs, and still deliver reduced road user costs, and reduced flood damage risk.

While the cumulative economic effect of the full-resilience model was negligible over 30 years across the case studies, for the stitch-in-time model the analysis calculated a cumulative lifecycle cost saving of nearly $600 million for a marginal benefit-cost ratio of 6.9.

A best-for-network strategy was also proposed, where the best option is chosen for each link, leading to an overall marginal benefit-cost ratio of 3.7. The anticipated life-cycle benefit of the best-for-network strategy could extend to $16 billion over the 30-year analysis period.

In addition, it was found that enhanced drainage maintenance across the state-controlled network will reduce the extent of damage. Based on this finding, $100 million of programmed maintenance, rehabilitation and drainage maintenance was accelerated in 2016-17.