The methods for calculating road wear on the Strategic Road Network take account of the cumulative effects of vehicle loading and speeds. The most important factor is vehicle loading. Road inclines, roundabouts and other road features are not explicitly taken into account, but the overall approach is based on much empirical evidence from national and international sources, which shows how pavements wear in real life conditions. The change to the mix of traffic is regularly monitored to adjust the wear factor. It is supplemented by monitoring vehicle axle loads at sample spots on the network, such as roads near port entries, freight distribution centres and weigh-in-motion sites. Current design and maintenance standards have enabled development of long life pavements on most of the network, requiring no substantial structural work so long as the road surface is replaced at appropriate points. Current road condition survey programme and maintenance strategies aim to ensure that there is no structurally unsound road pavement.