The results of geophysical studies are presented, the purpose of which was to assess the technical condition of two railroad bridges and their ground foundations in permafrost areas. It is shown that the passive seismic standing wave method makes it possible to determine the frequencies and shapes of several flexural modes of the bridge's natural vibrations, which can be used to assess its technical condition. This method is reduced to the recording of acoustic noise on the surface of the study object and accumulating the amplitude spectra of a large number of noise records. This makes it possible to extract from the noise standing waves formed in the study object under its influence and determine their parameters. The electrotomography of the soil foundation makes it possible to identify zones of thawed soils in the permafrost, which, together with the analysis of the bridge's natural modes, makes it possible to assess the potential danger of stability loss of its supports.