  The German motorway, or 'autobahn', is characterised by long traditions,
meticulous state planning, historical misbalance between West and East
Germany's transport networks, and highest increase in traffic in modern Europe,
posing a need for expansion and/or restructuring. We attempt to evaluate the
structure of autobahns using principles of intrinsic optimality of biological
networks in experiments with slime mould of Physarum polycephalum. In
laboratory experiments with living slime mould we represent major urban areas
of Germany with sources of nutrients, inoculate the slime mould in Berlin, wait
till the slime mould colonises all major urban areas and compare the
statistical structure of protoplasmic networks with existing autobahn network.
The straightforward comparative analysis of the slime mould and autobahn graphs
is supported by integral characteristics and indices of the graphs. We also
study the protoplasmic and autobahn networks in the context of planar proximity
graphs.
