used in this document are sufficiently narrow passages through any body of water which can be spanned with a bridge or ferry as well as transit to offshore islands and the like which can be linked by a bridge or ferry non water type inland barriers can include mountains 16 u2032 fig1 21 valleys and the like in the fig2 example road segments 18 20 comprise those portions of an overall road network 14 contained in a digital map but specifically located on adjoining sides of an inland water barrier 16 typically the road segments 18 20 will be of the type capable of supporting vehicular traffic flow although the principles of this invention are equally applicable to bicycle and pedestrian paths as well an automobile 22 is shown entering a ferry 24 for passage across the inland water barrier 16 to the awaiting road segment 20 fig3 is similar in many respects to fig2 however the inland water barrier 16 in this example comprises a river and a bridge 26 is provided to join or link the opposing road segments 18 20 accordingly vehicles 22 are able to cross from one road segment 18 to the other road segment 20 by traversing the inland water barrier 16 via the bridge 26 fig4 portrays a section of a digital map containing several road segments 14 an inland water barrier 16 in the form of a river passes in a generally east west direction road segments 18 20 are provided in the vicinity of the inland water barrier 16 and are shown.