§ 299.313 Track geometry; performance based.
(a) For all track of Class H4 and above, vibration in the lateral and vertical directions measured on the carbody of a vehicle representative of the service fleet traveling at a speed no less than 10 km/h (6.2 mph) below the maximum speed permitted for the class of track, shall not exceed the limits prescribed in the following table:
| Carbody acceleration limits 1 2 | |
|---|---|
| Lateral vibration 3 | Vertical vibration 3 |
| ≤ 0.35 g peak-to-peak | ≤ 0.45g peak-to-peak |
| 1 sec window | 1 sec window |
| excluding peaks < 50 msec | excluding peaks < 50 msec |
| 1 Carbody accelerations in the vertical and lateral directions shall be measured by accelerometers oriented and located in accordance with § 299.337(c)(3). | |
| 2 Acceleration measurements shall be processed through an LPF with a minimum cut-off frequency of 10 Hz. The sample rate for acceleration data shall be at least 200 samples per second. | |
| 3 Peak-to-peak accelerations shall be measured as the algebraic difference between the two extreme values of measured acceleration in any 1-second time period, excluding any peak lasting less than 50 milliseconds. |
(b) If the carbody acceleration requirements are not met on a segment of track, the segment of track is to be reclassified to the next lower Class of track for which it does meet the requirements of this part.