No. 16 Starts at Ban Nong Lek then continues to the Train station, Charoensri Complex shopping center, Irrigation Department, Matchimawas Temple, Central Post Office, Provincial Hall, Mukkhamontri Rd, TAT Office, Udon Sunshine Orchid Farm and then Nong Samrong.
(From Getting Around)
But I cannot find No.16 bus at Charoensri Complex.