Objective: to determine the influence on the frequencies and shapes of free vibrations of multi-span bridge structures of high-speed railways of such factors as the longitudinal modulus of elasticity of the connection of the rail with the sub-rail base, the stiffness of the supports in the direction along the bridge and the massiveness of the intermediate supports. Methods: the article considers a four-span bridge with a jointless path modeled as an elastic beam on an elastic base, for which the oscillation forms and their corresponding natural frequencies are determined for various parameters of the bridge-jointless path system. Results: the data presented in the article make it possible to take into account the presence of a jointless track on the bridge and its participation in the work of the bridge structure when designing bridge structures on high-speed railways, which makes it possible to make constructive decisions of the elements of the object more reasonably. Practical significance: since the dynamic reaction of a structure is entirely determined by its dynamic properties, it becomes extremely important to identify the spectrum of natural frequencies and oscillation patterns of a bridge structure when taking into account the operation of a jointless track on a bridge, which unites the structure into a single system, ensuring the compatibility of the elements of the bridge-jointless track system under longitudinal train and temperature influences, which It makes it possible to reflect the actual operation of the structure and, ultimately, allows you to build more economical bridge supports.