[OSM-dev] 1,074,201 things to do for OpenStreetMap, literally

[Dennis Luxen]

Fellow OpenStreetMappers,

Team OSRM is happy to announce a new data analysis feature for
OpenStreetmap data based on OSRMs great routing capabilities. Over the
past weeks, we at Team OSRM received a number of complaints that a
certain part of the road network was not route-able and were asked for
help. We observed that some of these error were not caused by obviously
invalid tagging, but by connectivity issues such as unconnected islands
of the road network, sources and sinks. Think of the latter two as
one-ways where you can drive in but not out, and vice-versa. There are
in fact 1,074,201 such way segments on the planet.

One assumption in reality is that the road network is (mostly) a
strongly connected component [1]. It is a technical term, but in essence
it means that you should be able to go from one intersection of the road
network to every other intersection. Especially, you should not get
stuck in a street that you can't get out of.

Head to OSRMs demo site [2] and activate the 'small components' layer or
use the routing view of Geofabriks great OSM Inspector [3] to see the
visualization.

A more detailed discussion on the possible error that are visualized can
be found on the web:

http://www.openstreetmap.org/user/DennisL/diary

Big thanks go to Geofabrik for hosting the tile layer.

--Dennis on behalf of Team OSRM

[1] http://en.wikipedia.org/wiki/Strongly_connected_components
[2] http://map.project-osrm.org/
[3] http://tools.geofabrik.de/osmi/?view=routing