Preliminary recommendations to improve traffic flow on I-285

I serve on the Georgia Department of Transportation's (GDOT) Citizens Advisory Committee (CAC) for the Revive285 project, which is attempting to put together a package of improvements to reduce traffic congestion on I-285.

Here are my preliminary recommendations to the CAC.

It seems like we reached a broad consensus on some fundamental concepts at the last CAC meeting. I would like to put on the table for discussion, a first shot at ideas for actual recommendations. If we all discuss these ideas by email, perhaps we can make some progress toward recommendations

1. I think we need to wind up making recommendations that are financially realistic and feasible. I would like for our objective to be to make recommendations that can actually be implemented, and implemented fairly quickly. There are lots of ideas that have been talked about for years. I would like for the CAC to develop a package of ideas that can move forward and be implemented quickly.

2. If we aren't adding lanes, and we aren't adding transit, and we are reserving land for future transit once the Region gets its act together, then we may wind up with a plan that is:

financially feasible
quickly implementable. (I think people are tired of studies and talk, and would like to see some kind of improvement actually happen.)

3. GDOT told us that the reason for congestion on I-285 is not an overcapacity issue. It is too much merging and lane switching. If we had fewer entry points, fewer exit points, and less lane changing, we can significantly alleviate congestion. Therefore

4. We need to fix the Spaghetti Junction choke point from I-285 eastbound (and Buford Highway) onto I-85 northbound, complicated further by the tangle with those who are trying to exit at Pleasantdale.

5. We have a mess on I-285 eastbound because of the tangle created by the Savoy Drive entrance onto I-285 eastbound tangling with the exit to Peachtree Industrial southbound.5. We have a mess on I-285 eastbound because of the tangle created by the Savoy Drive entrance onto I-285 eastbound tangling with the exit to Peachtree Industrial southbound.5. We have a mess on I-285 eastbound because of the tangle created by the Savoy Drive entrance onto I-285 eastbound tangling with the exit to Peachtree Industrial southbound.

6. Between Glenridge and Ashford-Dunwoody we have too many exit ramps, too many entrance ramps, and too much lane changing. It's a mess. We need some form of collector-distributor system. This could be

new side lanes that would be accessed somewhere before Glenridge (eastbound) and before Ashford-Dunwoody (westbound). Eastbound, you would take just this one exit for Glenridge, GA 400, Peachtree-Dunwoody, and Ashford-Dunwoody. This lane would also pick up all the entering traffic from these roads, and we would have one collective entrance onto I-285 beyond Ashford-Dunwoody. Westbound would also have only one exit and one entrance collectively for these same streets. This sort of "collector-distributor" could also provide exit ramps that would go directly onto Hammond Drive and Glenridge Connector. (No entrance onto 400 or 285 from Hammond.)
A variation of the concept in 6a, would be to convert the 2 outside lanes to collector distributor lanes, and barrier separate these lanes between Glenridge and Ashford-Dunwoody. I think this would work better if at least one lane were added in this section, but we can discuss this with or without the extra lane. My concern would be excessively reducing the number of through lanes. This would be counter-productive.
Another variation of this concept would be for the collector distributor to include Roswell Road. Therefore the western end of the collector-distributor would be west of Roswell Road, rather than just west of Glenridge. I might be persuaded to go along with this variation, if we study it and find that it can be implemented without adverse impacts to existing neighborhoods. I would also be concerned about adversely impacting implementability. The distance from Glenridge to Ashford-Dunwoody is pretty short. Extending the collector-distributor west of Roswell Road would significantly increase the length of the changes to I-285. Since any changes to I-285 will need federal approval, if we can keep this change shorter, we might have a better chance of federal approval. If we determine that either idea is equally implementable, and that it can be done without impacting neighborhoods, I would have to agree with David Welden that there would be benefits to extending the collector-distributor west of Roswell Road
Another approach to this problem would be a Spaghetti Junction type interchange in the GA 400 area with ramps connecting directly to Glenridge, Glenridge Connector, Hammond, Peachtree-Dunwoody, and Ashford-Dunwoody (and possibly Roswell Road). Obviously this would also be the interchange between 400 and 285, but would also provide direct ramps to all of these other roads, so that just like with the previous collector-distributor, you would have one exit from I-285 with a bunch of spaghetti ramps going to various roads, and various spaghetti ramps all connecting back up and having one collective entrance onto I-285 each way.
Right now, I am leaning toward the idea that the collector-distributor concept in 6a-c is better than the concept in 6d for the I-285 / GA 400 area. This concept would basically take this stretch of I-285 and barrier separate "through lanes" from "local lanes". In the through lanes, we eliminate all the lane changing and excessive merging. In the local lanes, we might have only 2 through lanes, with a bunch of exits and entrances. But the only people who would be in those lanes would be the people who actually want to exit and enter in this area. And with only 2 lanes in each direction, we eliminate massive amounts of lane-changing. So this gets directly to the problem that GDOT tells us actually exists on I-285

7. Expand the capacity of the Roswell Road bridge so that we could have adequate left turn storage in each direction, and have 2 free-flowing through lanes on Roswell Road in each direction.

8. Fix the Riverside Drive bridge for adequate left turn storage to allow one free-flowing through lane in each direction. Traffic lights are needed on both sides of the bridge.

9. And finally, a Spaghetti Junction type of interchange at I-285 and I-75. The spaghetti ramps could provide direct inter-connections to Cobb Parkway, Cumberland Boulevard, and Windy Hill Road (on ramps and off ramps). We could also explore the viability of exit-only ramps for Windy Ridge and Interstate North Parkway in the Cumberland area. These exit ramps could provide profound relief for some of the other existing interchanges. But again, the key is to make it have one exit ramp from I-285, from which you would access all the other localized ramps, and one entrance onto I-285 collectively from all of these interchanges.

If we can just find a way to get people off the highway more efficiently, and have fewer entrances causing excessive merging, we can probably create major congestion relief, and simultaneously enhance safety as a byproduct.

10. We also have the suggestion to take the two or three "inside" lanes in each direction, and barrier separate them, and make them express through lanes. If you are in those lanes, the only possible exits are I-75, GA 400, and I-85. If your destination is Riverside Drive, or Chamblee-Dunwoody, or Peachtree-Industrial, or Buford Highway, you use the local lanes. Based on what GDOT told us, BOTH sets of lanes might perform better, but clearly the express lanes would perform much much better. Even the local lanes could perform better because fewer people are crossing fewer lanes to get away from, or get to, the exit lanes. Right now I would view this idea as an alternative to the collector-distributor idea in # 6. Right now, I am more inclined to support the collector-distributor in # 6, because this would avoid building a whole additional set of entrance and exit ramps in the GA 400 area for the express lanes.

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