1. Applied Economics and Management; Cornell University; 405 Warren Hall Ithaca NY 14853
2. Beijing Transportation Research Center & Beijing Jiaotong University; No.9 Liu Li Qiao Nanli Fengtai District Beijing 100073 China
3. School of Economics; Renmin University; Minde Building 947 Zhongguancun Village 59, Haidian District Beijing 100000 China
4. The World Bank; 1818 H Street NW Washington DC 20433