OpenStreetMap

OpenStreetMap is a useful data source of road and rail geographic data. Other amenities and building outlines are also available.

We have been coordinating a project here: AddingJunctionsAndSidingsToOsm

ITO World show the OpenStreetMap rail data that is currently available in a set of maps.

Tools to help with working with OSM

 * Tags in OpenStreetMap with the UK
 * Harry Wood set up download location for railways data filtered from OpenStreetMap worldwide. Details are in his blog post