Gravity model in the Korean highway

We investigate the traffic flows of the Korean highway system, which contains both public and private transportation information. We find that the traffic flow T-ij between city i and j forms a gravity model, the metaphor of physical gravity as described in Newtons law of gravity, PiPj/r(ij)(2), where Pi represents the population of city i and r(ij) the distance between cities i and j. It is also shown that the highway network has a heavy tail even though the road network is a rather uniform and homogeneous one. Compared to the highway network, air and public ground transportation establish inhomogeneous systems and have power law behaviors. Copyright (C) EPLA, 2008.