A single line railway track over a road is supported by two trusses as shown in elevation in Fig. P.3.21(a). The load on the bridge produced by a train may be regarded as comprising two uniformly distributed loads, one representing the engine and one the line of freight cars as shown in Fig. P.3.21(b). With the front of the engine at mid-span, determine the distribution of shear force and bending moment in one of the trusses.