in 1963 the upper level was built east of field to serve the new outer drive east building. between 1970 and 1980, the viaduct was demolished east of columbus; this probably happened after the extension of wacker drive to lake shore opened in december 1975. by 1988 the new randolph had been completed, including a new upper level west of columbus. east of columbus, this level was built to slope down to the old upper level, which was orphaned by the move of lake shore drive in 1986. the old viaduct was kept west of columbus, and it slopes down to a middle level east towards the new lake shore drive.