OSM Inspector/Views/Routing

From OpenStreetMap Wiki
Jump to: navigation, search

The Routing view in OSM Inspector shows problems in the data related to routing and navigation.

Overview

OpenStreetMap data is not only for creating nice maps. Routing or navigating based on OpenStreetMap data is possible. But small errors in the data that might not show up in a normal map, can lead to suboptimal routes. This view helps by showing those kinds of problems.

Data sources

All data in this view is derived from OSM data.

Layers

This view has the following layers:

Unconnected major and minor roads

There are three layers for Unconnected major roads and three for Unconnected minor roads. They show where two ways almost meet with a distance of less than 1 meter, between 1 and 2 meters, and between 2 and 5 meters. This is not necessarily a bug. Maybe there is a gap and you can't get from one road or path to the other. But in many cases its just an oversight and the roads should really be connected.

Duplicate ways

The Duplicate ways layer shows lines where two ways tagged as highway=* lie on top of each other on the same nodes. This is probably a data entry error and should be fixed.

Islands

The Islands layer shows groups of road segments which are not connected to a larger network of roads. These roads are accessible for cars if you look at their tags but they are dropped by a routing engine because the car would be unable to leave this small subnetwork. There are multiple possible reasons:

  • There is no physical connection to a larger network, not even by a ferry. Keep in mind that ferries have to be connected to a road.
  • The roads which lead out of this subnetwork are not open for cars, e.g. due to an added access=private.

This layer is produced by osrm-components using the default car profile.

Sinks and sources

The Sinks and sources layer shows one-way roads which are not connected to the network at both ends. We call such a road a "sink" if it points towards the dead end. If it points from nowhere into the network, it is called "source". If the a public one-way road points into a private road, it is also considered as a sink because the private road is unusable.

This layer is produced by osrm-components using the default car profile.


Data Attributes

Every error in the layers "unconnected major roads", "unconnected minor roads" and "duplicate ways" consists of two objects, a way and a node referenced by their osm ids. The highwaykey represents the class of road involved in the error and has the following mapping:

  • 1=motorway
  • 2=motorway_link
  • 3=trunk
  • 4=trunk_link
  • 5=primary
  • 6=primary_link
  • 7=secondary
  • 8=secondary_link
  • 9=residential
  • 10=tertiary
  • 11=unclassified
  • 12=living street
  • 13=service
  • 14=track
  • 15=pedestrian
  • 16=cycleway
  • 17=footway
  • 18=bridleway
  • 19=steps
  • 20=tertiary_link, construction
  • 24=path


What you can do with this view to improve OSM data

Go through the duplicate ways and fix those cases. Sometimes whole ways overlap, sometimes only parts. Look at the tags of both ways, consolidate them and then remove one of the ways.

For the unconnected roads layer you have to look at the situation: If you know the area, you can connect the roads where they need to be connected and leave the others where there is a genuine gap. If you don´t know the area, use your good judgement. Sometimes its obvious from the context that some roads should be connected, but sometimes you just can´t tell and should leave things for others to fix.

Routing islands are often a tagging issue. In some cases they are a connectivity issue.

Sinks and sources are tagging issues (one-way streets leading into private areas where the street is split into two carriageways due to a check point at the entrance) or streets pointing into car parks and the mapper did not known the interior of this car park.

Statistics


See also / Siehe auch