This dissertation investigates the dynamics of highway bridges subjected to heavy vehicle loads. A convolution method based on bridge mode shapes is developed to predict the dynamic response of a bridge to a given set of wheel loads. The convolution integral is solved by transformation to the frequency domain. In order to validate the bridge response calculation method, an experimental procedure, consisting of impulse tests to determine the bridge modal properties and vehicle tests, is presented. The measured modal properties of the bridges are compared against predictions from beam theory and finite element calculations. Good agreement between theory and measurement is shown. The modal parameters are combined with measured wheel loads in the convolution calculation to predict bridge responses. These predicted responses are compared with the measurements and good agreement is found. The convolution method is extended by an iterative procedure to include vehicle models and two parametric studies are performed. In the first, the importance of the dynamic interaction between vehicles and bridges is investigated, and guidelines for determining when interaction can be ignored are presented. In the second study, the effects of vehicle suspension design on bridge dynamic response are considered. Vehicles with leaf-spring and air-spring suspensions are considered.