Country: Australia
Key Area: Transportation
Services: Performance Modelling

A desire to improve its pavement performance modelling (PPM) outcomes led the Mundaring Shire Council (MSC) to ask Opus for assistance. Situated due east of Perth, Western Australia, MSC manages 576 kilometres of sealed pavements. The pavements are predominantly thin surfaced flexible, with either a spray seal or asphaltic surfacing.

Opus provided robust inputs into MSC’s works programme to ensure it used all the available data and minimised whole of life costs, while maintaining network condition. To do this we created a PPM, which aimed to identify an appropriate investment level to sustain the network’s sealed pavements, develop a works programme to fit within the available funding, ensure the works programme achieved the best condition outcome for the available funding whilst minimising life cycle costs.

To ensure we delivered the best outcome for MSC we selected a team from Opus’ pool of experts. These included a New Zealand-based modeller and an Australian-based field team to verify our model in the field.

We based our model (which we customised to reflect local practice and objectives) on extensive information which we obtained from the Term Network Contracts administered by Main Roads Western Australia. Our process utilised the latest pavement inventory and condition data from MSC’s ROMAN system, which we reviewed for obvious omissions and inconsistencies. We then reviewed the model set up and sought feedback on it in terms of MSC’s practice, rationalised the number of pavement sections needed to produce a practical works programme, ran the model with the amended set up and data, reviewed its performance and sought feedback on the network level predictions.

We examined the maintenance actions available to MSC, applying a range of treatments and constraints to ensure the model produced reasonable treatment options. After identifying appropriate investment levels, we undertook an optimisation process to maximise the pavement condition for a fixed annual investment. We found that to sustain the network in its current condition over the medium-term, a 40% investment increase was required.  From this, we produced a programme of works, validated it in the field and identified future enhancements to the model and works programme development processes.

Our PPM helped MSC minimise whole of life costs while maximising pavement performance, developed a robust works programme within the funding constraints while aiming to sustain the current network condition and provided a scientifically-based system to compare engineering judgement in the field and capture institutional knowledge in a reusable medium.