| Postmiles | |
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Data format: Shapefile File or table name: Postmiles Coordinate system: Geographic Theme keywords: Transportation |
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Abstract:
Postmiles are valid TASAS postmile points at 0.1 (1/10th) mile intervals, based on Office of GIS Linear Referencing System layer (Tele Atlas North America linework). Exceptions are the beginning and ends of routes that don't necessarily begin or end on the even 0.1 mile interval. |
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Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.
Postmiles are valid TASAS postmile points at 0.1 (1/10th) mile intervals, based on Office of GIS Linear Referencing System layer (Tele Atlas North America linework). Exceptions are the beginning and ends of routes that don't necessarily begin or end on the even 0.1 mile interval.
Postmiles is used to display postmile locations on a map display, or to query for the purposes of finding a specific location reference by county, route, and postmile.
Postmiles are coded with the district, county, route, postmile prefix (if any), postmile, and postmile suffix (if any). Two additional fields - PMInterval and 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).
PMInterval indicates the interval on which the postmile falls: 0.001, 0.01, 0.1, 1, 5, or 10. This field is handy for drawing a subset of postmiles at desired intervals, for example this Definition Query will tell ArcMap to draw postmiles only at 1 mile intervals:
"PMInterval" >= 1
Though the vast majority of postmiles fall on a 0.1 (tenth mile) or higher intervals, postmiles are inlcuded that fall on a lesser interval. Examples are the beginning or end of a route or county, or at an equation point. These postmiles can be identified through use of the "HwySegment" field, that contains codes of "Begin County", "Begin Segment", "Mid Segment", "End Segment", and "End County". Begins and ends of routes are coded "Begin County" and "End County". A Definition Query that would tell ArcMap to draw postmiles only at 1 mile intervals or the begin of county would be:
"PMInterval" >= 1 OR "HwySegment" = 'Begin County'
AlignCode indicates if the postmile is on a Right alignment, Left alignment, Right side of an independent alignment, or Left side of an independent alignment. Where TASAS considers most state highways to have just a centerline, the underlying linework that the postmiles are based upon has a line for each direction. In some cases the right and left lines are identical (where there is no median). In other cases the right and left are separated (where there is a median, or dual carriageways), but TASAS treats the segment as a single centerline. In the last case the underlying linework has dual carriageways, and TASAS treats the segment as a split alignment (where there are independent right and left alignments).
In some cases (especially for small-scale mapping), it may be appropriate to display postmiles for just one alignment (e.g. Right alignment), and only for the other side where TASAS indicates independent alignments. In other cases (e.g. large-scale mapping), it may be appropriate to display postmiles for both alignments, regardless of how TASAS treats the segment.
This is an example of a Definition Query that would tell ArcMap to display postmiles at one mile intervals only on the right alignment where TASAS indicates just a centerline, and on both right and left alignments where TASAS indicates independent alignments:
"PMInterval" >= 1 AND "AlignCode" <> 'Left'
Similarly, only at 1 mile intervals or beginning of county, and not Left:
("PMInterval" >= 1 OR "HwySegment" = 'Begin County') AND "AlignCode" <> 'Left'
publication date
None
Internal feature number.
ESRI
Feature geometry.
ESRI
State Highway Route number.
Unique identifier of underlying Linear Referencing layer. RouteID along with Measure fields can allow these points to be re-dynamically segment points.
County (standard 3-character abbreviation).
Caltrans District (1-12).
Route suffix.
Unrelinquished route.
Postmile prefix.
Postmile.
Postmile suffix.
Combined postmile. Combined from PmPrefix, PM, PmSuffix.
Measure from underlying Linear Referencing layer. Along with RouteID could be used to re-dynamically segment points.
Postmile interval.
Thousandth mile interval.
Hundredth mile interval.
Tenth mile interval.
One mile interval.
5 mile interval.
10 mile interval.
Location along highway segment.
Beginning of a county (or of a route).
Beginning of a segment (where postmiling changes for some reason, e.g. an equation point).
Point along the segment. Not an end point.
Ending of a segment (where postmiling changes for some reason, e.g. an equation point).
Ending of a county (or of a route).
Alignment code
Falls on a right alignment (may be identical to left alignment)
Falls on a left alignment (may be identical to a right alignment).
Falls on a right independent alignment.
Falls on a left independent alignment.
Route Type - State, US, Interstate
State Highway
US Highway
Interstate Highway
50 Higuera Street