A method and apparatus for transforming a topological wire route to a physical wire route is described where the topological wire is a connected route having only a topological position determined with respect to terminals or obstacles. A topological wire is first selected and then obstacles which sight the selected wire are identified. A fan with a radius that is a predetermined number times a minimum space is then set to the identified obstacle as a forbidden region. A minimum space must be left between the selected wire and the identified obstacle. Finally, a shortest route is detected so that it does not pass through the forbidden region, and the route of the physical wire on the board is determined with the shortest route.