Figure 2

Traffic landscapes and exponent matrices for the twelve most populated cities in the USA. Each panel consists of the traffic landscape of the city on the map (top) and the exponent matrix derived from the traffic volumes between cells in the city (bottom). In the landscapes, each cell is colored according to the group it belongs to, following the color bar at the bottom of the figure. A higher value of k indicates the larger traffic volume of the group. For comparison, we mark the estimated distance exponent using the whole data of the city by a white bar in the color bar for exponent values