Beginning at its southern terminus with I-75, I-675 is a four-lane highway with a grassy median and frequently with cable barriers.

Between Ellenwood Road/Forest Parkway and the route's northern terminus at I-285 and Moreland Avenue, the freeway expands with three lanes in each direction.

[10] In 2006, a Reason Foundation report suggested a tunnel connecting I-675 to SR 400 and completing the originally proposed Interstate 420 estimating a cost of $4.8 billion.

[citation needed] In 2010, the proposal faced opposition from then-Atlanta mayor Kasim Reed and many residents of the areas it would pass through.

[14] An August 2010 GDOT feasibility study found that "no physical constraints exist along the proposed alignment that would preclude construction of a tunnel" and over a 75 year period, it would be expected to save 2.8 billion hours.