There are several shapes and mechanisms of pantograph on Shinkansen and conventional lines, and a method to measure contact force for most forms of pantograph has been developed. The contact force is determined from the force arising on a certain section of the pantograph (i.e. the section force), inertial force, and aerodynamic force. The section force can be obtained from the strain on the pantograph head or on the pan spring, while the inertial force can be obtained from multiple accelerometers attached to the pantograph head (Fig. 1) and equivalent masses of that. The method to obtain inertial force using an accelerometer is already widely used in Europe, and the measuring frequency of that method by an accelerometer is up to about 20 Hz, while the newly developed method by multiple accelerometers can measure up to 40 - 50 Hz (and up to 100 Hz for some types), enabling highly precise measurement.
      The aerodynamic force acting on the pantograph head, which was previously difficult to measure, can now be estimated from the section force and the contact wire deviation. The estimated aerodynamic force has been shown to closely correspond to the actual aerodynamic force obtained from the wind tunnel test (Fig. 2). The highly precise estimation of the aerodynamic force allows more accurate contact force measurement. In addition to the quantitative evaluation of current collection performance, the contact force can be used for the estimation of tension, local wear, and excessive stress of the contact wire, those are valuable for maintenance of overhead contact lines.