Caltrans contractors have scheduled a major freeway closure of Interstate 8 eastbound starting Thursday at 10 p.m. to erect a structure for a sign. The work, scheduled through 6 a.m. Friday, is part of the I-8 Pavement and Bridge Rehabilitation Improvement Project from El Cajon Boulevard to Marshall Avenue. The closure, which will begin near Jackson Drive, will detour all eastbound motorists to northbound state Route 125, then eastbound on state Route 52, southbound state Route 67 to eastbound I-8.