a rail vehicle includes a body with side walls having a frame including supporting beams for absorbing vertical forces and longitudinal beams extending horizontally . panelling is disposed on the inner side and the outer side of the frame and attached to the longitudinal beams . additionally , windows are disposed in the side walls and framed by the supporting and the longitudinal beams . the supporting beams extend obliquely to the longitudinal beams and engage in the respective recesses of the longitudinal beams .