Principal strains mapped across the arch barrel of bridge CFM-5 for a typical 2-carriage train travelling on the northern (top) track, for cases where the axle loads are applied directly above (a) rosette 3, (b) rosette 4, (c) rosette 5, (d) rosette 6, (e) rosette 7, and (f) rosette 8; ε₁ is compressive and ε₂ is tensile