A stretch of Interstate 81 south of Syracuse will be closed for construction over nights next week, according to the state transportation department. I-81 south will be closed from the exit at South Salina Street, South State Street and Brighton Avenue (Exit 17) to the exit for the Onondaga Nation and Nedrow (Exit 78) from 7 p.m. to 6 a.m. each day from Monday, September 30 to Thursday, October 3.