When working with National Bridge Inventory (NBI) coordinates I have found what appears to be an error in the raw data provided. I couldn't find any other mention of this specific error when searching for a solution to my problem. There seems to be dropped zeroes in the seconds portion of the DMS format used. According to the NBI Coding Guide the format of their coordinates is DDMMSSss. After I had converted this data to decimal degrees, plotted the points and compared it to known bridge locations I realized that several of these coordinates were incorrect. After trying a few different possibilities I discovered that there were missing zeroes in their data. For example:

  1. Raw Data
    Lat 34212979 Long 84565142
    Lat 34172838 Long 84584821
    Lat 34171338 Long 84452538
    Lat 34069870 Long 84461200
  2. Corrected Data
    Lat 34212979 Long 845605142
    Lat 341702838 Long 84584821
    Lat 341701338 Long 844502538
    Lat 340609870 Long 84460001200

Where the coordinate was 84 degrees, 56 minutes, 5.142 seconds the NBI data would record this without the place-holding zero in front of the seconds so that, according to their formatting, it would read 51.42 degrees instead. Even when the seconds are 0.012 the raw data would simply omit these place-holding zeroes and record 1200 in the seconds place. Out of 216 records there were 64 that were missing these place-holding zeroes. Had I not had pre-existing bridge locations to compare these to then 1/4 of my geocoding would have been incorrect.

My question is, How can I identify this incorrect data more easily in the future so that I don't have to go point by point to correct the formatting error? So far, the only solution I found was to double check the coordinates of all the points that I know to be incorrect. Also, has anyone else noticed such a problem with their raw data from the NBI? I didn't see any explanation for this in the NBI Coding Guide.

  • I don't have an answer for you but did you at least notify the NBI producers of the issue? – user77008 Jun 29 '16 at 4:09

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