An improved Dijkstra algorithm is set forward on the basis of priority queue based on quad-heap. It is proved in this paper that quad-heap is the optimum amongk-ary heap. The presented algorithm decreases the complexity of conventional Dijkstra algorithm toO(logn). Considering the dynamic characters of transportation applications

an inverse running sequence is presented based on the inverse adjacent list data structure. It is more suitable for the dynamic applications of GIS-T.