RIMS has recently completed a project to create a new Candidate Selection Algorithm (CSA).  The CSA provides a candidate site list for pavement and surfacing renewals.  This list can be field validated and prioritised to create the short term forward works programme for a road network.  If this sounds familiar, it is. This CSA will be an updated improvement to the Treatment Selection Algorithm (TSA). The project has been funded by the Roading Efficiency Group (REG).

Many a road asset manager will be familiar with the Treatment Selection Algorithm (TSA) that has sat within RAMM for the last 30 years or more.  In 2016 a Waka Kotahi (NZTA) research project was undertaken to look at improvements to this tool (Project 599).  This research noted:

  • The findings of the long-term pavement performance site monitoring
  • That condition measurement techniques and parameters have changed
  • economic analysis parameters have changed.

There were a number of recommended improvements:

  • the inclusion of new data sets such as falling weight deflectometer
  • and a better consideration of thin asphaltic surfacings.

One of the improvements in the research project was a change in name to better reflect the purpose of the tool, a candidate selection algorithm (CSA).  This reflected that the tool provides a candidate site list for field validation. This is opposed to the name “treatment selection” which implied a forward works programme that could be implemented directly.

RIMS implemented a programme to implement both the improvements to the CSA and develop and test that electronic algorithm.

The new CSA builds on the old system with the improvements and can be used to guide future surface and pavement works and reflect current knowledge and experience.

The outcome of the CSA enables development of a spreadsheet of treatment lengths, with supporting asset and condition data and a recommended treatment as follows:

  • Do Nothing (General Maintenance)
  • Reseal in Budget (this year)
    • chipseal 2nd coat, chipseal reseal, locking coat
    • thin asphaltic resurfacing
  • Reseal Next Time (next year)
    • chipseal or thin asphaltic resurfacing
  • Rehabilitation
    • light rehabilitation with thin asphaltic or chipseal surfacing
    • heavy rehabilitation with thin asphaltic or chipseal surfacing

The report includes the updated algorithm flowcharts and the data extraction “sql”.  The new CSA outputs were tested against the Auckland Transport 3-year field validated forward work programmes for South, Central and North Rural contract areas.