The issue of excessive structural vibrations caused by train operations is becoming increasingly prominent, and more and more retrofit measures are being taken on existing tracks. This paper focuses on sections already laid with elastic sleeper tracks, aiming to study the impact of replacing them with cast iron sleeper tracks to reduce vibrations. By establishing a dynamic coupling model of the vehicle-track-soil-building, this paper analyzes the structural vibrations of the building caused by train operations. It compares the vibration characteristics at the source and at the building using concrete elastic long sleepers and iron cast sleepers. The vibration reduction effects are assessed in two aspects: insertion loss at the tunnel wall and building vibrations caused by train operations. The insertion loss at the vibration source with cast iron sleeper scheme ranges from 1.2 to 22.0 dB, and the insertion loss for building vibrations ranges from 0.0008 to 19.4 dB.