Atlanta has lost arguably the last untapped part of the Perimeter. Through almost 15 years of reporting on Atlanta commutes for WSB Triple Team Traffic, I have seen I-285 have a mostly consistent pattern of slow zones. The worst parts of rush hours on I-285 have mainly been north of I-20 - and those still are the slowest zones. I-285 south of I-20 - and especially between I-75 and I-85 near the Airport - has normally (barring any wrecks) been a pristine wilderness of wide open traffic. But changes in the last few months have scarred this beautiful frontier.

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I-285 through and around the Airport’s fifth runway tunnel has become dependably slow during PM drive in recent times. I-285/westbound (Inner Loop) is regularly very heavy from just west of I-75 in Clayton County over to I-85 in south Fulton. And likewise, I-285/eb (Outer Loop) is slow working over to the busy I-75 interchange. Just to the east of that, I-285/eb has started to slow on random evenings trying to ramp onto Jonesboro Road/Highway 54.

Combine these changes with the increased volume on I-285 in both directions south of I-20 in DeKalb - and with that weird November spike in terrible wrecks in that area - and I-285 south of the "I-20 Equator" can no longer be taken for granted that it moves well.

But why have these conditions changed? That blame is far less definite to assign than the delays are noticeable. For one, if conditions on I-85 and I-75 are bad, they adversely affect I-285. A recent Gridlock Guy piece covered how hard accessing I-285 can be, but this is the opposite effect. This also shows how fragile interstate conditions are.

Most freeways have normal rush hour delay zones. But I-85 between Newnan and I-285 and the aforementioned area of I-285 have not. They really only get slow when they have wrecks or when the other freeway does and those delays slow them. I-85 may not have a normal jam each day, but the volume level southwest of town is high enough that any small problem jams it even worse than the same kind of problem would, say, on I-85 in Gwinnett. This characteristic is probably a big contributor to the changes on I-285.

Population increases have simply brought more traffic into most areas. That pressure increase isn’t as obvious on I-285 in Dunwoody, because the traffic there is already terrible. But the downgrade from speed limit to slow is far more noticeable, which is why I-285 on the south side is now part of the doldrums. The “fragile effect” is in play almost daily here: there are far more factors almost constantly that pollute this traffic ecosystem on I-285.

The economic boom of the last few years also, naturally, has taken its toll on the Perimeter. This portion of I-285 sees a large number of tractor trailers, which move slower and take up more room than other vehicles. And there are more big rigs not just because of the good economy, but because of the increased commerce in the newly-deepened Port of Savannah.

So more people and more trucks seem to be the main factors in the lost frontier on I-285. There also seems to simply be more traffic at the Airport to stir into the equation. But as much hand-wringing as can be done about the how and the why, the important factor is the what. There is no doubt that traffic on I-285 anywhere south of I-20 is much worse now. So plan your commute or Airport trip accordingly. Tune in to News 95.5/AM-750 WSB and Channel 2 Action News before leaving home and keep 95.5FM on in the car. And also download our Triple Team Traffic Alerts App and leave it running in the background on your phone as you drive to hear our automatic audio alerts about problems in the area.

So, cheers to I-285 near the Airport. We enjoyed you while you were good. But, alas, you are now just like every other Atlanta freeway.

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Doug Turnbull, the PM drive Skycopter anchor for Triple Team Traffic on News 95-5 FM and AM-750 WSB, is the Gridlock Guy. He also writes a traffic blog and hosts a podcast with Smilin’ Mark McKay on wsbradio.com. Contact him at Doug.Turnbull@coxinc.com.