A highway location reference system is a set of office and field procedures that includes a highway location reference method. The latter is a way to identify a specific location with respect to a known point. The system is seen as the procedures that relate all locations to each other and includes techniques for storing, maintaining, and retrieving location information. This report deals mainly with location reference methods, but recognizes that it is difficult to discuss methods apart from the system. The following methods are described: (1) the sign-oriented method (placement of either milepost signs or reference post signs along roadways); (2) the document-oriented methods (used because an agency did not want to incur the costs of installing signs in the field); and (3) other experimental methods, chief among them being the use of coordinates and the use of roadside land marks as reference points. There is not a great deal of difference between the most common methods. Little information on the costs of the various systems is available. The placement of physical markers remains a question. On two-lane highways, placement at alternating sides of the road has been used successfully by several states. On divided highways, a bettwe procedure is the placement on both sides. When two or more routes are concurrent, it is recommended that signs that include a route number contain the number of the highest level on the concurrency. It is also recommended that the public be informed as to the use of the such signing.
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