TIGER fixup

From OpenStreetMap

1 Fixing TIGER data
2 Accuracy: Offset from reality
3 Braided streets
4 See also

Fixing TIGER data

The TIGER data is of variable quality. Even though your county may have been uploaded already, it needs to be checked and fixed.

Each uploaded way has a tiger:reviewed=no tag. Once you reviewed a way, delete this tag.

Here is a partial list of things that have been found wrong with TIGER data:

Wrong-way motorway
Wrong-way motorway-link
Missing bits of motorway or railway
Only one direction of motorway
Wrong road classifications
Duplicate roads (same road in two counties dataset)
roads joined that don't
roads that cross on different levels get intersection nodes
railway and roads moved so they intersect when they don't
whole subdivisions misplaced by dozens of meters
distorted subdivisions
missing subdivisions
many points used to position a road wrongly
missing layer information (this is an always)
using obscure never-used rather than common names
missing ref on highways (another always)
no place names (but the TIGER data set has the names, so it would be possibly to upload these later) - Beej Jorgensen has imported the GNIS populated place names as of December 9, 2007 in lieu of this.
"braided" streets; see section below.

Accuracy: Offset from reality

The TIGER data is offset from reality in places. Unfortunately the Yahoo! Aerial Imagery is also offset in places, which can cause confusion. We should aim to measure reality as accurately as possible with GPS readings. If you can establish that an area is offset from reality, you can apply corrections by shifting a section of the TIGER data. Unfortunately this will need to be done on a localised basis. There's no general offset applying to all of the data. This is because the TIGER data is compiled from several sources of varying accuracy. See Talk:TIGER fixup#Tiger not matching Yahoo satellite pics

Braided streets

Example of braided street problem

Some streets in the TIGER upload look "braided", where dual ways criss-cross back and forth across each other. These should be fixed so that each side is consistent.

See http://trac.openstreetmap.org/browser/applications/utils/filter/osm-unbraid for tools to help find them and fix them.

There was a list here of examples needing cleanup. These ones have all been fixed.