This thesis aims at providing a deeper understanding of the dynamic effects in stress laminated timber bridges. The goal was to develop the dynamic design process for SLT bridges by finding crucial, influencing parameters that affect the acceleration and dynamic behaviour. The studied parameters were, inter alia, span-to-span ratios, damping ratios and density changes. The results showed that the accelerations correlated with multiple parameters and that a lot of improvements can be made in the design process.