A milepost equation, milepoint equation, or postmile equation is a place where
milepost
A milestone is a numbered marker placed on a route such as a road, railway, railway line, canal or border, boundary. They can indicate the distance to towns, cities, and other places or landmarks like Mileage sign, mileage signs; or they c ...
s on a linear feature, such as a
highway
A highway is any public or private road or other public way on land. It includes not just major roads, but also other public roads and rights of way. In the United States, it is also used as an equivalent term to controlled-access highway, or ...
or
rail line
Rail or rails may refer to:
Rail transport
*Rail transport and related matters
*Railway track or railway lines, the running surface of a railway
Arts and media Film
*Rails (film), ''Rails'' (film), a 1929 Italian film by Mario Camerini
*Rail ( ...
, fail to increase normally, usually due to realignment or changes in planned alignment.
In order to make mileposts consistent with the real mileage, every milepost beyond the equation would need to be moved.
For example, an equation of ''7.6 back = 9.2 ahead'' means that the feature does not have any section between mile 7.6 and mile 9.2, and the distance between mileposts 7 and 10 is only 1.4 miles. This would usually be caused by a relocation that shortened the distance by 1.6 miles. It is also possible for an equation to add mileage to what it would otherwise be; the duplicated mileposts receive a special prefix, such as Z.
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See also
* California postmile
California uses a postmile highway location marker system on all of its state highways, including U.S. Routes and Interstate Highways. The postmile markers indicate the distance a route travels through individual counties, as opposed to milep ...
References
Scales
Milestones
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