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To improve the efficiency of the road transport industry in New Zealand, a range of mass limit increases for heavy vehicles has been proposed.

Some of the options for mass increases include increasing the axle load limit, which would inevitably lead to increased road wear.

As New Zealand has a mass-distance road user charging regime where the users pay for the road wear they generate, this increased wear is in itself not a problem provided that the charges accurately reflect the wear.

At present, road user charges are based on the fourth power law, which was developed from the AASHO road test carried out in the United States in the 1950s. The pavements and vehicles used for that test differ considerably from those in use in New Zealand today.

To determine the effects of increases in mass limits on pavement wear, a multi-stage accelerated pavement testing programme was undertaken at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) between 1999 and 2001.

Stage 1 investigated the effect of increase in mass limits on pavement life on four sections that differed only by aggregate type.

This report documents stage 2 of the project and investigates the effect of increase in mass limits on the life of a chipseal surfacing.

For comparing the effects of an increase in mass limits, the axle load on one wheel path was 80 kN, while the load on the other was increased to 100 kN. 

Keywords: accelerated pavement testing, CAPTIF, heavy vehicles, loads, loading, mass limits, pavement, pavement loading, pavement performance, pavement wear, roads, road user charges, surface texture, thin-surfaced pavements, traffic, vehicles