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Interchange Index
I-85, I-285, GA 14 Spur, and GA 279
Red Oak, GA
Overhead Picture from terraserver-usa.com
Overview: This interchange lies on at the southeastern side of the subrubs of Atlanta, GA. I-85, which runs through Atlanta on its way from Montgomery, AL to Petersburg, VA, enters from the south at left, travels east for a short distance, and then leaves to the northeast at the right side of the aerial view here. I-285, at the southeastern corner of the beltway that it forms around the perimeter of Atlanta (also known as The Perimeter), enters from the north at left and leaves to the east. The third freeway, which leaves to the west, is GA 14 Spur; this travels a short distance to the west before ending at US 29 and GA 14. Lastly, the surface road that crosses I-85 and I-285 at center is GA 279.
From I-85, I-285 is Exit 68, GA 14 Spur is Exit 69A, and GA 279 is Exit 69B. (Southbound, Exits 69A and 69B are combined into Exit 69.) This interchange is considered both ends of the I-285 beltway. As a result, the exit is not numbered for "counterclockwise" (SB, coming from the north) traffic. For "clockwise" traffic (WB, from the east), I-85 is Exit 61 and GA 279 and GA 14 Spur are both Exit 62. Exits are not numbered on GA 14 Spur.
Because of the large size of this interchange, I've broken it down into three main parts: the four-way junction of I-85, I-285, and GA 14 Spur; the simple diamond interchange at GA 279; and the three-way junction of I-85 and I-285.
I-85, I-285, and GA 14 Spur:
At first glance, this may seem to be very similar to many simple four-way interchanges. It is simply a variation on a cloverleaf, with flyover ramps to replace some of the loop ramps. However, it is really a little more complex than that. Because of the fact that three roads lead out of the interchange to the east, and three seperate roadways lead into it from the east, there are a few more ramps than usually found in a simpler four-way junction.
Entering from the west, on GA 14 Spur, a driver has three choices. The first is a simple ramp on the right side, which leads to I-85 SB. The second, after crossing under a few ramps, is a loop ramp which brings traffic to I-285 NB. Finally, any traffic that didn't exit is put onto the outermost (southernmost) of the three roadways that leave to the east. The ramp to GA 279 leaves this road, and traffic can eventually reach I-85 NB and I-285 EB as well.
From the north, there are a few more ramps available. The first split for I-285 SB traffic actually occurs north of this photo's coverage. The ramp to the right leads into this photo, and then splits to allow access to GA 14 Spur WB on the right and GA 279 via a loop ramp. (This is the loop in the southwest quadrant of the interchange; traffic can also reach I-85 NB and I-285 EB from here, but there are more direct routes, so this isn't marked.) A second split occurs as traffic enters the interchange; here, drivers can bear left to stay on I-285 (which becomes the middle of the three EB roadways) or go straight ahead. Going straight leads to either a left exit for I-85 NB (the innermost of the three roadways) or a ramp for I-85 SB.
From the south, I-85 traffic first has an exit (Exit 68) for I-285. This ramp, which leaves the I-85 mainline south of this photo, eventually splits between I-285 NB and I-285 EB (again, the middle of the three roadways.) Next, Exit 69A is a flyover ramp that leads to the west, merging onto GA 14 Spur. Finally, Exit 69B is marked as GA 279; this merges into the remnant of GA 14 Spur EB, and the exit for GA 279 follows soon thereafter. (Again, traffic can exit at Exit 69B and then reach I-85 NB or I-285 EB, but this route is a little longer and requires weaving across other traffic bound for GA 279, so it is not marked.) The remainder of I-85 becomes the innermost eastbound roadway.
From the east, three roadways enter the interchange. The outermost (northernmost) carries traffic coming from GA 279, I-85, and I-285; however, most of the traffic is bound for GA 14 Spur. Two ramps leave this roadway; the first is an exit for I-285 NB, and the second is a loop ramp to I-85 SB. Both of these are only used by traffic coming from GA 279.The middle of the three roadways coming from the east is the I-285 mainline; this simply curves to the right, with no exits. Likewise, the I-85 SB mainline simply curves to the right with no exits. (Access from these two highways to each other and to GA 14 Spur is available farther east; read on for details.)
The GA 279 Interchange:
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This interchange is a simple diamond interchange; however, there are more than the usual number of roads running under the underpass. The innermost divided highway is the I-85 mainline; the next road on either side is the I-285 mainline (which has darker pavement), and the outermost roadways are the eastern extension of GA 14 Spur. Exits to and entrances from GA 279 only intersect the outermost roads; access to and from I-285 to the north and I-85 to the south was available at the first part of the interchange. Traffic bound for, and traffic coming from I-85 to the north and I-285 to the east can access these highways at the easternmost part of the interchange, shown in the next aerial photo.
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I-85 and I-285:
The easternmost portion of this interchange is basically a souped-up "semi-directional T" interchange, a 3-way interchange where the through road has all of its entrances and exits on the left side. However, as a result of the high volume of traffic and the three roadways entering and exiting the west side, a large number of extra ramps are added to provde full connections at the GA 279 and GA 14 Spur interchanges, as well as to prevent weaving between I-85 and I-285 traffic. Another factor that complicates the design here is the proximity of another interchange; although it's not shown in this view, I-85's intersection with GA 139 (Exit 71) is just north of here. The roadways that flank either side of I-85 lead to the ramps for this exit.
From the east, on I-285 westbound, Exit 61 leads to I-85. This splits off just east of this photo's range, and then splits traffic between I-85 SB (the innermost westbound roadway leaving the interchange) and I-85 NB. The ramp to the northbound lanes splits again; the branch on the right leads to Exit 71 for GA 139, while the left merges directly into I-85. Exit 62, for GA 14 Spur and GA 279, splits off further west, and joins the roadway that eventually becomes GA 14 Spur.
From the north, traffic bound for I-285 must exit the freeway further north, along with traffic for Exit 71. The colllector/distributor road for I-85 SB, which also contains all of the traffic from GA 139, splits three ways: the left fork goes to I-285 EB, the middle to I-285 NB, and the right to GA 14 Spur. Traffic traveling from I-85 SB to GA 14 Spur and GA 279 has a more direct route; it can use Exit 69, which exits the mainline very near the 3-way split in the collector/distributor road. The remainder of the through traffic on I-85 SB ends up on the innermost of the three highways traveling west from this point.
Lastly, traffic coming from the west actually has very few options. The road from GA 14 Spur and GA 279 splits two ways; the left joins I-285 EB, while the right fork ducks under I-285 and joins the northbound collector/distributor road on I-85. (This traffic can rejoin the I-85 mainline after Exit 71, about a mile to the north.) The I-285 EB roadway runs straight into the I-285 mainline without any more exits, and the I-85 roadway just has a simple slip ramp to the Exit 71 collector/distributor road.
Comments: This highway junction is, in my opinion, one of the better ones in the country. Despite the fact that one major interregional highway, a well-traveled suburban beltway, and a connecting freeway (which also serves as a sort of bypass for Red Oak) come together at one point along with a major surface road, this interchange was built to offer quick and easy connections in every possible direction. No connections are missing from this junction, and most are even built with flyover ramps instead of loop ramps to offer faster connections. The only freeway-to-freeway connection that must use a loop ramp is from GA 14 Spur EB to I-285 NB; the other two loop ramps are only for traffic coming from and going to GA 279. In addition, there are no left exits from any freeway; I-85, I-285, and the full length of GA 14 Spur (all the way to the eastern end of the interchange) only have exits and entrances on their right side. There is no weaving on either of the two Interstate highways; there is only a small amount on GA 14 Spur associated with the GA 279 exit; and a small amount on the collector/distributor roads on I-85 to the north, as a result of the close proximity of Exit 71.
The only disadvantage I can see in this interchange is its high cost; just the sheer amount of pavement between the two ends of the interchange is staggering. Add to this the cost of all of the bridges required for ramps in the western and eastern ends of the interchange, and the result is phenomenal.
An interesting side note: on most state maps of Georgia, and in fact on almost any map that doesn't show street-level detail, it appears as if I-85 and I-285 overlap for about .6 miles at this interchange. However, a closer look at the interchange reveals that they never actually share the same roadway; they are always seperated, if only by a concrete barrier.
Links
- I-285 at kurumi.com
- I-285 at interstate-guide.com - Lots of pictures of this junction
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Corrections? Suggestions? More information is always welcome.
Suggestions for more interchanges to cover on this site are great too.
Contact the author, Dan (known as DanTheMan on misc.transport.road):
twowheel@email.com
