The Effect of Electric Heavy Vehicles on Flexible Pavements in Australia: A Review

Decarbonisation of heavy vehicles to achieve net-zero greenhouse gas emissions, through the adoption of Zero-Emission Heavy Vehicle (ZEHV) technologies, inevitably influences vehicle typology and axle mass distribution. The additional weight of batteries used in ZEHV systems must be accommodated within existing vehicle mass limits. In Australia, the freight industry is advocating for a minimum one tonne increase in the allowable steer axle load to facilitate greater uptake of electric heavy vehicles. This desktop review investigates the potential effects of a one tonne increase in steer axle load on flexible pavements of both local roads and rural national highways. Currently, there is no nationally standardised methodology for assessing unacceptable pavement wear. This study compares several approaches and concludes that the use of mechanistic-empirical method with weigh-in-motion (WIM) data provides a more accurate assessment of pavement wear than analyses based solely on individual vehicle axles or total vehicle axle loads. The pavement wear analysis indicates that the steer axle contributes the greatest cumulative distress across all pavement types examined. Furthermore, the results show that a one-tonne increase in steer axle load would have a substantially greater impact on local roads- leading to an estimated 31.3% to 48.7% reduction in pavement life- compared with a 20.9% reduction in rural national highways.