  We present two methods to compress the description of a route in a road
network, i.e., of a path in a directed graph. The first method represents a
path by a sequence of via edges. The subpaths between the via edges have to be
unique shortest paths. Instead of via edges also via nodes can be used, though
this requires some simple preprocessing. The second method uses contraction
hierarchies to replace subpaths of the original path by shortcuts. The two
methods can be combined with each other. Also, we propose the application to
mobile server based routing: We compute the route on a server which has access
to the latest information about congestions for example. Then we transmit the
computed route to the car using some mobile radio communication. There, we
apply the compression to save costs and transmission time. If the compression
works well, we can transmit routes even when the bandwidth is low. Although we
have not evaluated our ideas with realistic data yet, they are quite promising.
