State Highway Network Lines

StateHighways is used to display state highways on a digital map display. Each record represents a segment of California state highway where the county, route, postmile prefix, and postmile suffix are unchanging, and there are no gaps or overlaps in the postmiles. Each segment is coded with the district, county, route, postmile prefix (if any), begin postmile, end postmile, and postmile suffix (if any). One additional field - AlignCode - should be understood by the user for effective use of this data set (refer to the Entity and Attribute Information section of this metadata). AlignCode indicates if the state highway segment is on a Right alignment, Left alignment, Right side of an independent alignment or Left side of an independent alignment. Where TSN (Transportation System Network - the source database) considers most state highways to have just a centerline, the underlying LRS (Linear Referencing System) linework that these segments are based upon has a line for each direction. On undivided highways the right and left lines are identical. On divided highways the right and left are separated, but TSN treats the segment as a single centerline. In the last case where highways are not only divided but also have different lengths (where the right and left carriageway diverge around physical obstacles or are separated onto different one-way streets) the underlying linework has dual carriageways, and TSN treats the segment as an "independent alignment".  In some cases (especially for small-scale mapping), it may be appropriate to display linework for just one alignment (e.g. Right alignment), and only for the other side where TSN indicates independent right and left alignments. In other cases (e.g. large-scale mapping), it may be appropriate to display postmiles for both alignments, regardless of how TSN treats the segment. This is an example of a query string that displays linework only for the right alignment where TSN indicates just a centerline, and on both right and left alignments where TSN indicates independent alignments: "AlignCode" <> 'Left'.The bOdometer and eOdometer fields represent the actual distance in miles from the start of the highway to the begin and end of each highway section.  This is in contrast to the begin and end postmile values, which no longer represent these values as each highway is realigned (and made longer or shorter) over time.