From OpenStreetMap Wiki
After the GeoBase data has been imported, it needs to be cleaned up. There are several common errors which need to be cleaned up:
- Streets from the GeoBase NRN data need to be joined up to existing streets in the OpenStreetMap data.
- Some streets from the NRN data which are very close to existing streets in the OSM data might be omitted. These need to be added from the "complete" or "excluded" file for the GeoBase tile you are working in.
- The NRN data includes road names only in British Columbia, Alberta, Prince Edward Island, Nova Scotia, Yukon and Nunavut. In all other provinces and territories, road names have been automatically added from the Statistics Canada Road Network dataset with RoadMatcher. However, this process isn't very accurate, and road names are often not matched correctly. This needs to be fixed by adding the road names manually from the Statscan dataset, which is available here. (Download in shapefile format and use OpenJump to add road names from Statscan). The Statscan dataset should not be imported directly into OSM as the road network is not geographically accurate, however it is topologically correct and generally very up-to-date.
- Roads previously traced from Yahoo imagery or Landsat may not have names. Add them from GeoBase (in provinces where the NRN data has road names) or Statscan (otherwise).
- Motorways need to be cleaned up: motorways should be tagged with highway=motorway, and motorway slip roads should be tagged with highway=motorway_link.
- One-way streets are not included in GeoBase and need to be surveyed. However many one-way streets will be tagged as "lanes=1" (though the direction is inaccurate) so this will help you find areas with one-way streets to add.
- In some areas the GeoBase data is poorly aligned with reality and needs to be cleaned up. In a few cases (generally in new subdivisions) it is totally wrong, and needs to be fixed.