To improve the riding comfort of high-speed trains, advanced semi-active suspension for railway vehicles is becoming more and more necessary. The goal of this work is to develop a semi-active suspension with better performance than the ones in current use, at a lower cost. By a reexamination of system design, a new type semi-active suspension utilizing electrical relief valves was designed and the cost of equipment was cut by 40%. Running tests of this system were performed on the Tokaido Shinkansen line and the test results assure that the new system is more effective at damping vibration than the ones in use.