A longitudinal tractive force analysis is carried out by including horizontal forces of magnitude 343 kN (35 t) based on an average field-measured value at the rail level and at wheel positions. For this analysis, a tensile strength of 0.2 MPa is assumed for both the brick masonry and the filler material. From this analysis, it was observed that cracking initiated at the crown of Span 1 at a live load of 637 kN (65 t), offering a margin of safety of 2.6 with respect to a 245-kN (25-t) axle load. Furthermore, no cracks were observed at the springing of the pier and abutments, suggesting that the hinging mode of failure is unlikely. The failure of the arch through the formation of hinge near the crown can take place only if there is excessive horizontal movement at the springing of the abutment.
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