"路线测量" can be translated into English as "route surveying" or "route measurement".
"Route surveying" is a more commonly used and professional term in the field of surveying and mapping, referring to the process of measuring and determining the geometric elements (such as length, direction, elevation, etc.) of a route.
"Route measurement" is a more straightforward translation that also conveys the basic meaning of measuring a route, though it may be slightly less technical in some contexts.
In most professional or technical settings, "route surveying" would be the preferred choice.