Dialigned Roads

As seen on my screenshot, the blue-colored road polyline which is downloaded from OS Open Roads is misaligned over the basemap. Those ROADLINK networks are under British National Grid coordinate system. How to correct them?

The software used was ArcGIS Desktop 10.4.1. The shift is approximately 106 meters.

  • 1
    Did you make sure that the CRS of the road are the same like the basemap? May 28 '17 at 9:24
  • 1
    I assume that the network layer is not set with the correct datum shift against WGS84. Please include details on the software you are using to show both layers. And please measure the shift in meters.
    – AndreJ
    May 28 '17 at 18:32
  • The CRS.. I am not sure but the base layer is at same projection as the road layer.
    – khaliff
    May 29 '17 at 16:17
  • The software used was ArcGIS 10.4.1. The shift is approximately at 106 meters (Am I right in assuming that the shift is the align gap between the two layers?)
    – khaliff
    May 29 '17 at 16:21
  • @Hornbydd I think your comment has enough to make into an acceptable answer.
    – PolyGeo
    Jul 5 '17 at 23:20

The offset you are observing is because you have not set the transformation for the map, you've probably only set what coordinate system it should be displaying in.

You need to set the transformation from WGS to British National Grid. When you set the data frame coordinate system there is a button with the word transformation on it, click it, should be very obvious what to set, choose the transformation ending in the word petroleum.

Setting the Transformation

There are other transformations, but this one should be sufficient.

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