A programme of research was undertaken to better understand chip loss on curves with the aim to improve chipseal design and selection practices. The research involved on-road measurements and computer simulation of tyre forces during cornering manoeuvres; correlation analysis using road surface, road geometry and traffic variables contained in the NZ Transport Agency's RAMM database; and finite element analysis of pavement surface stresses induced by a cornering truck. The key findings were: 1. There was not a particular chipseal type more prone to chip loss than others. 2. It was determined from the finite element modelling that even at lateral accelerations five times the level normally expected for properly designed curves, the stresses generated in single coat chipseals were insufficient to cause failure of the binder in large enough areas to cause chip loss. 3. The RAMM variable that correlated the strongest with chip loss on curves was the NZ Transport Agency administration region suggesting climate, sealing properties or construction practices as being the main drivers not lateral acceleration. These findings support previous research that it is not seal design but construction practices, notably the use of controlled traffic to bed the sealing chips, which have the largest influence on mitigating chip loss. (Author/publisher)
Abstract