Interstate 285 (Georgia)

Interstate 285 (I-285) is an auxiliary Interstate Highway encircling Atlanta, Georgia, for 63.98 miles (102.97 km). It connects the three major Interstate Highways to Atlanta: I-20, I-75, and I-85. Colloquially referred to as the Perimeter, it also carries unsigned State Route 407 (SR 407) and is signed as Atlanta Bypass on I-20, I-75, and I-85.

Because of suburban sprawl, it is estimated that more than two million people use the highway each day, making it one of the busiest Interstates in the Atlanta metropolitan area, and one of the most heavily traveled roadways in the US. During rush hour, portions of the highway slow, sometimes to a crawl.

I-285 is 8 to 12 lanes wide, with the northern part from I-75 to SR 400 to I-85 the most heavily traveled. One segment of the highway near Tom Moreland Interchange (a large, flyover highway interchange northeast of Atlanta colloquially called Spaghetti Junction) with I-85 widens to 18 lanes, including collector–distributor lanes. Exits are numbered clockwise, starting at the southwesternmost point at I-85 and ending just east of there where it meets I-85 again near Hartsfield–Jackson Atlanta International Airport.

Between I-85 and I-20 in southwest Fulton County, I-285 is designated as the Bob A. Holmes Freeway (named after the member of the Georgia House of Representative), where I-285 heads north, and has an interchange with the Langford Parkway. Between I-20 in northwest Atlanta and I-75 near Cumberland Mall, it is designated as the James E. 'Billy' McKinney Highway (named after the member of the Georgia House of Representatives) as it continues north and starts to curve to the east just west of the I-75 interchange.

The northern portion of I-285, east of the Cobb Cloverleaf (I-75 interchange) to Spaghetti Junction (I-85 interchange), is frequently called the Top End Perimeter. This section, which includes an interchange with SR 400 at exit 27 (frequently cited as the most dangerous intersections in Atlanta), is one of the busiest freeways in the US, handling about 250,000 cars per day and crossing through Cobb, Fulton, and DeKalb counties, with several interchanges (SR 141, SR 13, and I-85) bringing additional traffic to and from Gwinnett County. Through that stretch, the freeway expands from six or eight lanes to between 10 and 14  lanes.

While I-285 does not travel through Gwinnett County, the highway travels very close to the DeKalb–Gwinnett county line, and many major highways in Gwinnett County connect to I-285, with some prominent ones being US Route 78 (US 78), I-85, and SR 141. Major Gwinnett cities near I-285 are Peachtree Corners and Norcross.

From exit 25 to exit 27, I-285 is concurrent with US 19.

Much of Atlanta's high-end commercial real estate has developed along I-285, particularly at the northwestern I-75 and the SR 400 interchanges. Notable buildings include the 35-story Concourse at Landmark Center in the Perimeter Center business district and the Cobb Galleria complex in the Cumberland area.