How frequently must train service personnel verify the accuracy of their handheld gauges?

Train service personnel must verify the accuracy of their handheld gauges every 90 days to ensure that all measurements are reliable and safe for operation. This time frame allows for regular maintenance and calibration of equipment without being overly burdensome, enabling personnel to focus on other critical tasks involved in train operations. Regular verification at this interval balances operational efficiency with safety and performance standards, ensuring that any discrepancies can be identified and corrected before they impact service quality or safety.