Notes on Transportation line data, SDTS format
The transportation line data (roads, railroads, and miscellaneous transportation features such as pipelines) converts quite smoothly to a shapefile via DLG format. The match between attributes converted this way and converted in Arc/Info, and then comparing both to the original DLG files, is good. The major difference noted is in the coincident feature attribute (where one feature represents different attributes in different files).
The feature attribute primary module for roads contains the letters ARDF in the name: for railroads the module contains the letters ARRF, and for miscellaneous features the module contains the letters AMTF. In some cases there may be a coincident attribute primary module with the letters ACOI in the name. This coindcidence module is fairly common in roads and public land survey data layers with regularly shaped geographic features.
The SDTS2DLG program creates a DLG and a DLA file when run. Running the DLGBLD program links the records within the DLG file. The DLA file contains information about the topoplogy of the data (line, node, etc) and functions as a link between the attribute information and the actual topology features. The first column indicates Area, Point, Line or Node. The second links to a record id in the attribute file (RCID), while the next column links to an attribute id in the attribute file (ATID and RCID). The fourth column matches the minor code in the DLG file, and the last points to the file where the attribute will be found (most often the feature attribute primary module).
The following is sample data from the roads DLA file, directly after conversion and delimiting. There were no commas after the initial letter or before the final set of letters in the files tested.
N, 60, 1, 1 ,ARDF
N, 62, 2, 2 ,ARDF
A, 165, 165, 1009 ,PC01
A, 166, 166, 1010 ,PC01
L, 849, 1628, 5298 ,ARDF
L, 1476, 2246, 5936 ,ARDF
L, 1476, 29, 5937 ,ARDM
L, 1477, 2247, 5938 ,ARDF
The ATTR2DAT program creates a file from the feature primary attribute module. This file contains attribute information in a useable format. There is quite a bit of information in the roads DAT files with unclear purposes. The file is bascially an ascii delimited text file, although it is created with a DAT extension. Only the first two columns were retained when testing the data, and no problems due to deleting the other data were observed.
1,1700005, , , , , , , , , , , ,-9,-99, ,
2,1700005, , , , , , , , , , , ,-9,-99, ,
3,1700005, , , , , , , , , , , ,-9,-99, ,
4,1700005, , , , , , , , , , , ,-9,-99, ,
In addition to the DLA and DAT files, there is another file in the roads data that indicates route number for the highways where that is applicable. A sample of that data is illustrated below; the data was obtained by running the ATTR2DAT program on the tr01ardm.ddf file (the other programs were not needed for this process). The resulting file was then treated like the other DAT files.
Sample route data:
7,SR 121 ,
8,US 287 ,
9,US 36 ,
The DLA and DAT files for railroads and miscellaneous transportation features were similar in format to the roads data; sample data is shown below. There are some differences in the DAT file, mainly in the number of fields of data (each comma below in the line delimts a field).
Railroad DLA file sample
A, 29, 29, 28 ,PC01
A, 30, 30, 29 ,PC01
L, 6, 4, 35 ,ARRF
L, 7, 5, 36 ,ARRF
L, 8, 6, 37 ,ARRF
Railroad DAT file sample
1,1800201, , , , , , , , , , , ,-9,-99,
2,1800201, ,U, , , , , , ,Y, , ,-9,-99,
5,1800208, , , , , , , , , , , ,-9,-99,
6,1800201, , , , , , , , , , , ,-9,-99,
7,1800201, ,U, , , , , , ,Y, , ,-9,-99,
Miscellaneous Transportation features DLA file sample
A 4, 4, 3 PC01
A 5, 5, 4 PC01
L 3, 2, 7 AMTF
L 5, 3, 8 AMTF
Miscellaneous Transportation features DAT file sample
1,1900401, , , , , , ,-99,
2,1900202, , , , , , ,-99,
3,1900401, , , , , , ,-99,
For additional information regarding this Web page, contact Deb Southworth Green, in the Division of Information Technology Management, at Deb_Green@fws.gov
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Keywords=GIS, data, metadata, steering, standards
Last Modified January 04, 2001 10:03 AM