This is not true - their original (and current) purpose is to calibrate the distance travelled by looking at the marks the tracks make - you can look at the dis

This is not true - their original (and current) purpose is to calibrate the distance travelled by looking at the marks the tracks make - you can look at the distance between marks and use the circumference of the wheel to determine the distance travelled. The actual pattern meaning was snuck in by the engineers and the director was only told about it after he had approved the design.