The identification of the traffic load positions suitable to give the maximum / minimum design actions on the various elements of interest is carried out through an automated procedure, typical of the LUSAS finite element system, which involves the processing of the surfaces of influence of the various stress characteristics, in the points of interest through a “Direct Method Influence” (DMI) analysis, preliminar to the search for the most unfavorable traffic load positions, through a “Vehicle Load Optimization” (VLO) analysis. The stresses N, T, M in the points of interest of a beam-shell model are obtained by integrating the results on “slices” of the model placed independently of the mesh; the influence surfaces, defined in order to evaluate the maximum / minimum bending and shear stress on the most stressed longitudinal beam, can be calculated, either in correspondence of the mesh nodes or of the slices. The following figure shows, through red rectangles, the schematic positioning of the various “slices” on which the surfaces of influence have been made (only 2 spans of the deck has been studied for symmetry).  “Slices” positions for influence surfaces (red rectanguls)   The “Vehicle Load Optimization” analysis generates as many loadcases as there are maximized / minimized stresses at a given slice. The following figure shows the load pattern, generated by the VLO, which maximizes the bending moment on the girder placed on the outside curve, in correspondence with the support of the pile P1; the arrows in red represent the tandem loads while those in magenta the distributed loads, segmented on the roadway according to the indications of the surface of influence.   Traffic load pattern generated automatically by the “Vehicle Load Optimization” analysis – Loadcase that maximizes My of the girder placed on the outside of the curve on the P1 pile