1. Doctoral Student, Dept. of Urban and Civil Engineering, Tokyo City Univ., 1-28-1 Tamazutsumi, Setagaya 158-8557, Japan; Highway Technology Research Center, 3-10-11 Toranomon, Minato 105-0001, Japan (corresponding author).
2. Associate Professor, Dept. of Urban and Civil Engineering, Tokyo City Univ., 1-28-1 Tamazutsumi, Setagaya 158-8557, Japan.
3. Maintenance and Transportation Division, Metropolitan Expressway Co., Ltd., 1-4-1 Kasumigaseki, Chiyoda 100-8930, Japan.