ISO 19133 Tracking and Navigation Standard: 6.6 Linear Reference System Standard

Most information maintained by a department of transportation (DOT) includes a physical location to specify where the data apply. Most often, this location is described with a linear referencing method (LRM). Because no single method is best for all applications, multiple methods are often used in each DOT. Engineers use stationing to locate construction items. Transportation data administrators may use mile point to locate roadway characteristics. Safety officers often use reference markers to locate crashes. TRB has stated that location can serve as an integrating concept for assimilating data from multiple sources. Until now, there were no standards for linear referencing methods; they vary between databases and between DOTs. Consequently, it has been difficult to integrate data from numerous sources by using locations with disparate formats. A new ISO standard should help remedy this situation. The ISO 19133 tracking and navigation standard includes a package for linear reference systems. It generalizes how linear locations are specified to enable translation between locations from different methods. It is based on the generalized model for linear reference, an abstraction of the NCHRP 20-27 conceptual model. According to the standard, locations are formalized as position expressions composed of a method of measurement (LRM), a linear element along which the measure is made, and the measurement itself. Locations can be on the linear element or offset laterally to either side. This paper explains the standard, how it was derived, and its implementation at the Minnesota DOT in its location data manager project.