Vehicle–pavement interaction is not only a central problem to pavement design, but also has a profound impact on infrastructure management, vehicle suspension design, and transportation economy. Figure 1 shows a central role of vehicle–pavement interaction played in a wide variety of applications. From a  vehicle-design point of view, a designer needs to consider vehicle vibration and controllability, which affect ride quality and vehicle maneuver. Vehicle–pavement interaction also has a huge economic impact. As pavement performance deteriorates and roadway surface gets rougher, both operation costs (fuel, tire wear, and routine maintenance) and roadway maintenance cost of the vehicle increase dramatically, accompanied by decreasing transportation productivity. There is no doubt that there is a great and urgent need for fundamental research on vehicle–pavement interaction due to rapid deterioration of huge highway infrastructure nationwide, tight maintenance budget, and the key role played by vehicle–pavement  interaction.

Since the American Association of State Highway Officials (AASHO) road test, the fourth power law has been widely used by pavement engineers to design high- way and airfield pavement and to predict the remained life and cumulated damage of pavements [1–3]. Besides the damage caused by static loads, dynamic loads may lead to additional pavement damage. A consequence of a high power in the damage law is that any fluctuation of pave- ment loading may cause a significant increase in the damage suffered by pavement structures. A number of recent filed measurements and theoretical investigations showed that vehicle vibration-induced pavement loads are moving stochastic loads [4–8]. The researchers concluded that vibrations of vehicles were related primarily to pave- ment surface roughness, vehicle velocity, and suspension types [9–13].

Estimation of pavement damage caused by dynamic loads varies anywhere from 20 % to 400 % [14]. The smaller estimates are based on the assumption that peak dynamic loads (and hence the resulting pavement damage) are distributed randomly over the pavement surface. The larger estimates are based on the assumption that vehicles consistently apply their peak wheel loads in the same areas of the pavement. Theoretical studies by Cole [15] and Hardy and Cebon [16] confirmed that for typical highway traffic, certain areas of the pavement surface always suf- fered the largest wheel forces, even when the vehicles  had a wide range of different suspension systems, payloads, and speeds.

Complicated relationships exist among vehicle suspen- sion, dynamic wheel loads, pavement response, and dam- age [17–19]. On one hand, it has been known for years on how to manufacture automobiles operating properly on a variety of pavement surfaces. On the other hand, however, the effect of vehicle design on pavement has not been thoroughly studied. For instance, Orr [20] stated in his study that comparatively little was known about the influ- ence of suspension design on pavement in the automobile industry yet.

A number of obstacles exist in revealing vehicle–pave- ment interaction. A theoretical foundation universally applicable to the involved specific problems is no doubt very attractive. It will not only provide a guide for exper- imental study and validation, but will also enable better design and maintenance of vehicles and pavements. As such, this article provides an overview of a unified theory for dynamics of vehicle–pavement interaction under mov- ing and stochastic loads. This article covers three major aspects of the subject: pavement surface, tire–pavement contact forces, and response of continuum media under moving and stochastic vehicular loads developed by Sun and his associates (Fig. 2). The remainder of this article is organized  as  follows.  Section 2  addresses   mathematical description of pavement surface roughness. Section 3 studies contact force generated due to vehicle–pavement interaction, which is the source to both vehicle dynamics and pavement dynamics. Section 4 investigates pavement response under moving stochastic loads. Section 5 dis- cusses difficulties and deficiencies in the existing research, and projects further research and applications. Section 6 makes concluding remarks.