Abstract: Objective: There are multiple instances of side\|crossing viaducts in the underground excavation project of Hefei Rail Transit lines. It is necessary to study the construction impact of the tunnel structure in close proximity to the side\|crossing viaduct and select a reasonable construction scheme to effectively improve construction safety. Method: The CRD (cross road deck) excavation project at the affiliated entrance/exit No.1 of Tianzhu Road Station on Hefei Rail Transit Line 2 is studied. Using MIDAS GTS/NX numerical simulation software, environmental impact analysis numerical models under different construction conditions are established. The deformation of bridge caps, columns, and the bridge pile foundation, and the surface settlement of the ground near the viaduct are analyzed. The numerical simulation results are compared and analyzed with the monitored results on\|site. Result &Conclusion: The measured ground settlement curves at the monitoring points are consistent with the simulated curves, verifying the accuracy of the calculation. For the construction of shallow buried tunnel side\|crossing the existing viaducts, the working condition of excavating the far elevated side construction section first is better than that of excavating the near elevated side construction section first, and the working condition of 6m bench length in CRD method is better than that of 3 m bench length. The ground settlement above the tunnel changes greatly during the first three parts of CRD excavation and support removal, and then tends to be stable; The surface settlement at the edge of the pile cap will be reduced due to the friction resistance of the bridge pile to the stratum. The impact of shallow buried tunnel side\|crossing construction on the horizontal deformation of bridge bearing platform and pile foundation is greater than on the vertical deformation, and the impact on the bearing platform and pile foundation near the shallow buried tunnel side is greater than on those near the far shallow buried tunnel side.