EM-120」軌道線形檢測車係由奧地利Plasser & Theurer公司生產，以接觸式量測軌道的軌距、水平、方向、高低、平面性等參數，最高檢測速度120 km/hr，目前台灣高鐵線上實際檢測速度為80 km/hr。量測作業係於夜間維修時間帶進行，檢測工作頻率每月進行一次。此外，高鐵公司派員隨乘於700T營運列車上，在前駕駛室司機員座椅後方裝置加速規（列車動搖測試儀），檢測列車行駛之動搖狀況，同為每月檢測一次。每月提出「軌道線形與動搖測試報告」量測結果，可供維修人員瞭解軌道線形並做及時養護，以維持列車高速行駛時之平穩舒適。
The EM-120 track survey car is manufactured by Plasser & Theurer in Austria. It uses contact measurement method to measure the parameters such as gauge, cross level, alignment, longitudinal level and twist, etc. of the track. The maximum detection speed for THSR is 120 km/hr, and the current actual detection speed is 80 km/hr. Measurements are carried out at night maintenance time, and the frequency of survey is performed once a month. In addition, the vibration status survey is also performed once a month. It is conducted by THSRC staff where the inspector rides on an operating 700T train and installs an accelerometer (train vibration detector) at the rear of the driver’s seat in the cab to record and inspect the vibration status. The monthly “Track Survey and Train Vibration Report” can be used as reference for maintenance personnel to understand the track alignment condition and perform appropriate maintenance actions to maintain the stability and comfort during HSR operation.
The standard gauge of the HSR is 1,435mm. The track survey car has three bogies; there is a measuring wheel on both sides of each bogie, and the measuring wheels of the first bogie measure the gauge. The cross level is measured by three measuring wheels using 10m-chord; the longitudinal level is measured by 10m-chord with sensors on the 2nd, 4th and 6th axis of the three bogies; the 20m-chord and the 40m-chord are derived from the Multiple-Precision floating point number. Cant is the difference in the relative heights of the left and right rails. In the direction of increasing mileage position, the cant value is positive when the left rail is higher than the right rail, whereas the value is negative when the right rail is higher than the left rail. The track twist (distortion) is the difference between the cant measurement values between the two points of 2.5 m distance. Up to now, the test result report shows that the quality of the entire track is maintained in good condition.