There are many existing bridge structures in some valley areas all around the world. The stiffness of these bridge structures is generally small due to the slenderness of the high piers, and thus, vibrations can be easily excited by any external loads such as moving vehicle loads and/or wind loads. Meanwhile, the vibration of the bridge will in turn excite the vibration of the moving vehicles and affect the ride comfort of the passengers. Based on the vehicle-bridge coupled vibration, the 3-D vehicle model which can consider the effect of the patch contact on the dynamic response of the bridge-vehicle coupling system, and the impact factors of the existing bridges are presented.