City of Stirling Transport Asset Managment Plan

5.3 Renewal/replacement plan Renewal expenditure is major work which does not increase the asset’s design capacity but restores, rehabilitates, replaces or renews an existing asset to its original service potential. Works increasing an asset’s service potential are classified as an upgrade/expansion or new works expenditure. 5.3.1 Renewal plan Renewal is undertaken using ‘low-cost’ renewal methods where practical. The aim of ‘low-cost’ renewals is to restore the service potential or future economic benefits of the asset by renewing the assets at a cost below the replacement cost. The City has implemented prediction modelling and decision criteria for

renewal of its transport assets using Assetic’s MyPredictor software. It should be noted that MyPredictor modelling software has an optimisation component that assesses each treatment and determines which treatment should be applied, taking into account whole-of-lifecycle costs. As an example, the optimisation undertaken within MyPredictor will always prefer to undertake least expensive treatments over more expensive treatments such as reconstructions. It will therefore be necessary in some instances to re-evaluate the treatment selected by the software and give priority to major roads. For modelling purposes, the following options have been used:

Treatment name

Note

Deep lift asphalt (major roads)

Deep lift asphalt or recycle on major road Restore extensive pavement defects. Mill min 100mm Rehabilitation options to be determined subject to detailed investigation Subsequent overlay can be single layer Two-layer asphalt on major road Restore minor pavement defects. Mill and fill 55-60mm Usually on DD roads, subsequent overlay can be single-layer Single-layer asphalt on major road If the existing pavement is in good condition, ie, following a two-layer, deep lift or recycle treatment Overlay or mill and lay 30mm 7mm SMA or 10mm DG with PMB at intersections Single-layer asphalt on minor road Preferred treatment for minor roads usually 25-30mm thick 7mm SMA or 7mm DG Kerb line milling is often undertaken to tie into existing crossovers Two-layer asphalt on minor road Used when a minor road has deteriorated extensively or shows extensive block or ‘crocodile’ cracking due to base course failing. Mill and fill 50-60mm Applied between resurface treatments. Predominantly on Major Roads. Only once between treatments

Two-layer asphalt (major roads)

Single-layer asphalt (major roads)

Single-layer asphalt (minor roads)

Two-layer asphalt (minor roads)

Crack sealing

42