Rail–Viaduct Interaction on India’s First Continuously Welded Rail: An Experimental Study

Continuously welded rails (CWRs) are widely used on modern railway lines. However, CWR tracks over viaducts experience nonlinear dynamic interactions under thermal and vehicular loads, leading to track buckling or fractures if not managed properly. To better understand the behavior under train–induced loads, a 2-km-long ballasted CWR viaduct, the first of its kind on the Rohtak–Gohana railway stretch, was instrumented and monitored under several passenger and freight trains. This study, focusing on three critical spans, namely, adjacent to the abutment, near the prestressed concrete U-slab girder, and the tallest span, revealed that the span near the abutment experienced higher relative longitudinal track displacements, elevated rail stresses, and greater vertical accelerations compared to the other spans. Additionally, vertical track displacements measured relative to the deck were observed to be consistently greater than the corresponding longitudinal displacements. Also, across all cases of train passings, the tensile and compressive axial rail stresses under train loads constituted 27% and 25% of RDSO’s (Indian standard) threshold values, respectively. Furthermore, experimental modal analysis indicated a 13%–20% decrease in the fundamental frequency of the viaduct under train loads. These findings can provide a good understanding to develop appropriate numerical models and better design considerations in the Indian subcontinent and elsewhere in the context of CWR.