To design a bridge, different typologies of construction materials can be used. All materials have in common that deformations occur due to different events, such as externalloading, temperature- and moisture variations. To allow these kinds of deformations,Expansion Joints (EJs) are used in the structure. In timber bridges, these joints haveturned out to be a complex construction detail, due to problems related to their strengthand moisture capacity. The purpose of this thesis is to overview design codes and tostudy the mechanical behavior of Nosing EJs in a roadway timber bridge under externalloading. The aim is to identify critical actions and provide an alternative design of thestudied EJ. The aim is also to create a Finite Element (FE) model of the EJs and carryout calculations according to the design codes. To achieve this, literature studies, designcalculations and FE-simulations were performed. It turned out that there were lack ofearlier studies within this field. Therefore, studies which treats EJs in bridges with othermaterial than timber were considered. The results from the simulations indicated thatthe steel components in EJs are the most exposed parts in the detail. It also turned outthat an eventual failure can transferred away from the screws to the parts consideredmore favorable in the EJ.