sentences:  When the western section of I-640 was completed in 1982, I-75 was moved to overlap the auxiliary route to divert through traffic away from downtown in preparation for the 1982 World's Fair.This concurrency is somewhat unusual in that the exit numbers and mile markers follow the auxiliary route I-640 instead of I-75 mileage.An approximately five mile section of I-75 in northern Bradley and southern McMinn Counties, including the bridge over the Hiwassee River is prone to hazards from dense fog in the morning, which can severely obscure the visibility of drivers.