please contact Christian Sommer for comments and questions, or if you have other data sets.
last update April 2010
used for shortest path queries, DIMACS means 9th DIMACS Implementation Challenge  Shortest Paths
copied from DIMACS
A graph contains n nodes and m arcs Nodes are identified by integers 1...n Graphs can be interpreted as directed or undirected, depending on the problem being studied Graphs can have parallel arcs and selfloops Arc weights are signed integers 

By convention, shortest path graph file names should have the suffix .gr. Line types are as follows. In the format descriptions below, bold characters should appear exactly as typed:  
Comment lines can appear anywhere and are ignored by programs.  c This is a comment 
The problem line is unique and must appear as the first noncomment line. This line has the format on the right, where n and m are the number of nodes and the number of arcs, respectively.  p sp n m 
Arc descriptors are of the form on the right, where U and V are the tail and the head node ids, respectively, and W is the arc weight.  a U V W 
Some of the DIMACS graph files that come with coordinates can be visualized using Google Earth and KML. The program compiled from the source code kmlgen.cpp takes as input a .gr and a .co file of the same graph and generates a .kml file.