the most common road application of wim data is probably pavement design and assessment. in the united states, a histogram of wim data is used for this purpose. in the absence of wim data, default histograms are available. pavements are damaged through a mechanistic-empirical fatigue process that is commonly simplified as the fourth power law. in its original form, the fourth power law states that the rate of pavement damage is proportional to axle weight raised to the fourth power. wim data provides information on the numbers of axles in each significant weight category which allows these kinds of calculations to be carried out.