Road cut slopes in mountainous regions often experience small-scale collapses and landslides that cause serious traffic disruptions. To quantify their destructive potential, this study establishes a quantitative evaluation model for hazard intensity of road cut slope geohazards, integrating dynamic indicators (velocity, impact force, impact pressure) and accumulation indicators (volume, movement distance). Using Fangqian Town, Pan’an County, Zhejiang Province as a case study, 173 road segment units were delineated and analyzed through field investigation and testing following Typhoon In-Fa (2021). Multiple failure modes were identified, including falling, scattering, sliding, wedge-type, and toppling. Results show that the segment exhibits the highest potential intensity, with a velocity of 46.4 m/s, an impact force over 6.5 × 104 kN, and an impact pressure of 123.8 MPa under rainfall conditions. Empirical regression for landslide and collapse movement distances achieved high accuracy (R2 = 0.93 and 0.81). The proposed method effectively quantifies hazard intensity at a regional scale and provides a scientific basis for geohazard early warning and risk management of mountain road systems.