Editing Linear referencing (section)

==Motivation==
A system for identifying the location of pipeline features and characteristics is by measuring distance from the start of the pipeline. An example linear reference address is: Engineering Station 1145&nbsp;+&nbsp;86 on pipeline Alpha&nbsp;=&nbsp;114,586&nbsp;feet from the start of the pipeline. With a reroute, cumulative stationing might not be the same as engineering stationing, because of the addition of the extra pipeline. Linear referencing systems compute the differences to resolve this dilemma.

Linear referencing is one of a family of methods of expressing location. Coordinates such as [[latitude and longitude]] are another member of the family, as are [[landmark]] references such as "5 km south of Ayers Rock."  Linear referencing has traditionally been the expression of choice in engineering applications such as road and pipeline maintenance.  One can more realistically dispatch a worker to a bridge 12.7&nbsp;km along a road from a reference point, rather than to a pair of coordinates or a landmark.  The road serves as the reference frame, just as the earth serves as the reference frame for latitude and longitude.