Traffic Analysis Zones Design using Spatial Development of K-means Algorithm

Traffic analysis zones represent locations of trip generation and attraction. These zones are widely used in many urban transportation planning activities. Proper design of the mentioned zones is very important, because they cause considerable effects on the results of different transportation modeling and analyses. In this paper an efficient method is proposed to design these zones using geospatial information system. By using this method, various criteria can be considered to determine homogeneous traffic analysis zones whereas the number and size of the zones can be controlled as well. In the proposed method, the k-means technique is used for clustering basic areal units to homogeneous traffic analysis zones. To prevent overlaps and gaps between the zones and creation of the zones with too large or small sizes, some constraints are added to the k-means technique. However, definition of homogeneous zones without considering their geometric compactness results in generation of zones with complex shapes. For solving this problem, a geometric algorithm is developed to create continuous and compact zones. Efficiency of the proposed approach has been tested through to redesign the existing traffic analysis zones of Tehran city and its comparison with the existing traffic analysis zones. Results showed that the redesigned traffic analysis zones with the proposed method have been more homogeneous than the existing zones. Also, by using the shape compactness algorithm, compactness of the resulting zones increases whereas their homogeneity decreases. However the redesigned zones are more homogeneous than the existing ones.