20260527 18444100 1.0 TRUE 002 dataset Department of Transportation tim_tadlock@dot.ca.gov 20250806 ArcGIS Metadata 1.0 File Geodatabase Feature Class Caltrans tim_tadlock@dot.ca.gov TenthPMs_20250608_TSN Department of Transportation LRS Feedback@dot.co.gov Caltrans tim_tadlock@dot.ca.gov Postmiles are valid postmile points at 0.1 (1/10th) mile intervals, based on the Caltrans Linear Referencing System. Exceptions that are included are the beginning and ends of routes (and other situations) that don't necessarily begin or end on the even 0.1 mile interval. This geometry is based upon the extraction from TSN on 8 June 2025. . Route geometry updates based upon this extraction include routes 3, 36, 38, 49, 89, 139, 174, and 221. All updates received an update date of 6/8/2025 except for route 221 which received a date of 7/1/2025. Postmiles is used to display postmile locations on a digital 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). The source of data is the Caltrans TSN (Transportation System Network) database. 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 larger intervals, postmiles are included that fall on a smaller 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 TSN considers most state highways to have just a centerline, the underlying linework that the postmiles 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 Postmiles 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 Definition Query that would tell ArcMap to display postmiles at one mile intervals only on the right alignment where TSN indicates just a centerline, and on both right and left alignments where TSN 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' The Odometer field represent the actual distance in miles from the start of the highway to the postmile. This is in contrast to the postmile value, which no longer represents this value as each highway is realigned (and made longer or shorter) over time. California Department of Transportation (Caltrans) Department of Transportation Caltrans tim_tadlock@dot.ca.gov Transportation, Postmiles Transportation, Postmiles Postmiles is made available to the public solely for informational purposes. Information provided is accurate to the best of our knowledge and is subject to change on a regular basis, without notice. While Caltrans makes every effort to provide useful and accurate information, we do not warrant the information to be authoritative, complete, factual, or timely. Information is provided on an "as is" and an "as available" basis. The California Department of Transportation is not liable to any party for any cost or damages, including any direct, indirect, special, incidental, or consequential damages, arising out of or in connection with the access or use of, or the inability to access or use, the Site or any of the Materials or Services described herein. Please do not redistribute this dataset. Refer requestors back to Caltrans. Esri ArcGIS 2.9.7.32739 true -124.264846 -114.298297 32.544311 42.005472 Attribute accuracy is high, but not 100%. Errors are based on currentness of source database (TSN), or may result as dataset ages. Horizontal accuracy is only as good as the TIGER layer, generally within 5 meters. Data are sourced from the Transportation System Network (TSN) database, restructured into the Caltrans Reference Section table, restructured into an Event table which is then Dynamically Segmented onto the Caltrans Postmile Network in the Roads and Highways Linear Referencing System. 311109 EPSG 9.8(3.0.1)