Length of Single Rail Indian Railways has standardized a rail length of 13 m (previously 12.8 m) for broad gauge and 12 m (previously 11.8 m) for MG and NG tracks. And is denoted by L. Length of Single Rail is usually measured using the Meter for Length. Note that the value of Length of Single Rail is always positive. Typically, the value of Length of Single Rail is greater than 0.