I-85, Clairmont, and Briarcliff Road (Atlanta, Marietta: homes, new construction, schools)

[bu2]

Originally Posted by toll_booth

I mentioned this in another thread but I think it bears its own discussion.

Traffic around the I-85/Clairmont interchange is a complete cluster, especially in the evenings. The main backups are from 85 northbound and Clairmont southbound. 85 traffic spills back all the way to the interstate, and I've seen Clairmont traffic back up as far as Buford Highway!

I see some big problems with the design. One is that all this traffic is trying to squeeze into just two lanes going south on Clairmont. Another is that 85/Clairmont is a fairly standard intersection but with U-turns and access roads. It's a very common design you see in places with a lot of access roads such as in Texas. Third, the intersection just south at Briarcliff forms a bottleneck.

This whole area needs to be reworked.

1. The offramp from 85 northbound needs to be moved back at least half a mile. Too much merging and weaving in a short distance. Wouldn't hurt to move back the onramp to I-85S either.

2. Forbid left turns on or off Clairmont between 85 and Briarcliff. I don't care how much of a hassle that creates for businesses and residents there, those left turns are just adding to the problem. They can do U-turns elsewhere on Clairmont.

3. Right turns from 85N access to Clairmont southbound needs to be two lanes with full right-of-way with a "keep moving" arrangement. This means we've now got 4 southbound lanes on Clairmont, but because of #2, we can use the existing center turn lane as one of these southbound lanes. End the rightmost lane at some distance south of 85.

4. Turn Briarcliff into an overpass over Clairmont. It will have to be seen whether this bridge should be just north or just south of the current alignment.

5. Build a short connecting road between Clairmont and Briarcliff with traffic lights on both ends like this. This would either go southeast or southwest of the existing intersection.

Another option is to rework the 85/Clairmont interchange itself, but the access roads limit the options. DDIs are out of the question; SPUIs could work.

This would take a lot of resources and would displace some businesses, but this stretch of Clairmont (and Briarcliff) has got to get fixed.

This area is horrible and horribly designed.
#1. Definitely. And reversing the on ramps so it is before the intersection is also a good idea.
#2. There aren't a lot of businesses in that stretch that don't have access to Briarcliff so I can go along with this.
#3. Not sure this can be extended long enough to make it useful. If it becomes a right turn only at Briarcliff, it causes its own backup.
#4. I think this is essential to solve the problem. But I would make it an underpass and have Clairmont be the street that is the underpass. It would require some policing to make sure speeds didn't get excessive south of Briarcliff.
#5. Not sure if this would be worth the cost and fit the geography. There's a big hill on the southeast corner and a big new residential development near the southwest corner. But it goes to the root problem. Dekalb is basically a bunch of cul de sacs. To get north from Decatur or Druid Hills, Clairmont is the only road that goes through. Nothing really goes through east of Decatur until 285 either. Briarcliff goes N-S for a while then does a 90 degree turn and intersects Clairmont. Then Clairmont is the only street going north to Peachtree. Shallowford, like Briarcliff, goes N-S for a ways and then turns more E-W. There are similar problems going E-W.

[sedimenjerry]

Originally Posted by bu2

Texas has been shifting to this model in busy areas. The older access roads have the entrance after the intersection.

I remember Bryan/College station was the "older" style on 6 until the beginning of this decade, then they switched it to the newer style. They also bumped the speed limit to 75 several years ago (from 65 or whatever) but then dropped it to 70 not longer after which honestly was the right call as that stretch is pretty busy. Mid day I rarely could get to 75. Not really congested, just slow drivers.

Now that I think about, 99 between 10 and Westpark is the more standard style but it also doesn't have frontage roads to begin with.

I don't know if GDOT would do anything like that since that stretch of 85 is pretty much the only section in Georgia I can think of with frontage roads like TX.

[toll_booth]

Originally Posted by bu2

This area is horrible and horribly designed.
#1. Definitely. And reversing the on ramps so it is before the intersection is also a good idea.
#2. There aren't a lot of businesses in that stretch that don't have access to Briarcliff so I can go along with this.
#3. Not sure this can be extended long enough to make it useful. If it becomes a right turn only at Briarcliff, it causes its own backup.
#4. I think this is essential to solve the problem. But I would make it an underpass and have Clairmont be the street that is the underpass. It would require some policing to make sure speeds didn't get excessive south of Briarcliff.
#5. Not sure if this would be worth the cost and fit the geography. There's a big hill on the southeast corner and a big new residential development near the southwest corner. But it goes to the root problem. Dekalb is basically a bunch of cul de sacs. To get north from Decatur or Druid Hills, Clairmont is the only road that goes through. Nothing really goes through east of Decatur until 285 either. Briarcliff goes N-S for a while then does a 90 degree turn and intersects Clairmont. Then Clairmont is the only street going north to Peachtree. Shallowford, like Briarcliff, goes N-S for a ways and then turns more E-W. There are similar problems going E-W.

An alternative to #3 is to get rid of those U-turn lanes, shift everything over on the northbound access road left by one lane at the intersection, thus giving them two left turn lanes, a straight-only lane, and two right-turn lanes. Also get rid of that concrete island between the two right-turn lanes. Taking the suggestion to make this a SPUI would make U-turning not too difficult. (This part, if it's not clear what I'm talking about.)

Or they could shift the lanes to the right, but there's a solid chunk of rock there and taking that thing down would increase costs.

Another thing I've failed to mention is that there are no pedestrian signals anywhere! Shouldn't be that hard to do down the east side of the interchange (parallel to Clairmont); the infrastructure is already there, you just need the proper signals and barriers.

[ATLTJL]

No, no, no, cq's right....

You can't build your way out of this problem. Throw a bunch of buses at it. That should right things!

[jsvh]

You can't widen your way out of traffic. Rebuilding this interchange to handle more cars will simply result in more traffic clogging local streets.

CQ is right, we need to improve higher-capacity options like transit in the area.

[arjay57]

One thing I particularly dislike is that if you're exiting I-85 and need to turn right on Clairmont, you have to cross over the access lanes. And in a very short, poorly delineated space. With people from the access road on your right trying to merge into the left lanes!

That is not only a traffic snarl, it's downright dangerous.

I'm glad this thread was started as this area badly needs attention.

[bu2]

Originally Posted by jsvh

You can't widen your way out of traffic. Rebuilding this interchange to handle more cars will simply result in more traffic clogging local streets.

CQ is right, we need to improve higher-capacity options like transit in the area.

There is virtually nothing in the transit plans that would do anything at all for this intersection.

And many of the things suggested are simply maximizing what you already have and limited cost.

With Emory Children's opening on the corner and redeveloping Executive Park (from which 1/2 the original office space from the 80s has been torn down) and the move of Cross Keys HS to the old Briarcliff HS site, the intersection will just get worse.

In addition, vacant and underutilized land is being redeveloped into residential throughout this section of Dekalb as is that area near the SW corner of Clairmont and Briarcliff.

[jsvh]

Originally Posted by bu2

There is virtually nothing in the transit plans that would do anything at all for this intersection.

And many of the things suggested are simply maximizing what you already have and limited cost.

With Emory Children's opening on the corner and redeveloping Executive Park (from which 1/2 the original office space from the 80s has been torn down) and the move of Cross Keys HS to the old Briarcliff HS site, the intersection will just get worse.

In addition, vacant and underutilized land is being redeveloped into residential throughout this section of Dekalb as is that area near the SW corner of Clairmont and Briarcliff.

ART bus line is planned to go right through there as CQ pointed out.

Spending millions trying to increase car-volume through the interchange does not make any of things you mention better. It just results in more traffic. We don't need more traffic on the roads in that area.

[bu2]

Originally Posted by jsvh

ART bus line is planned to go right through there as CQ pointed out.

Spending millions trying to increase car-volume through the interchange does not make any of things you mention better. It just results in more traffic. We don't need more traffic on the roads in that area.

I suggest you try driving it regularly before saying these things are useless.

The problem is that it doesn't move and it generates situations that can contribute to dangerous traffic accidents.

And as I pointed out, there WILL be more traffic in the area. Emory is expanding at N. Druid Hills and 85 (which needs similar improvements) and housing is being developed all around Clairmont/Briarcliff and 85. The area along Clairmont north of 85 is getting redeveloped as well.

[samiwas1]

Originally Posted by jsvh

You can't widen your way out of traffic. Rebuilding this interchange to handle more cars will simply result in more traffic clogging local streets.

I don't think anyone has really mentioned widening the roads in the area. I think pretty much every recommendation has been a redesign of existing infrastructure. Redesigning entrance and exit ramps, using different intersection types that are more efficient, and improving signal timing.

Originally Posted by jsvh

ART bus line is planned to go right through there as CQ pointed out.

Helpful if you happen to be going on exactly that route.

Spending millions trying to increase car-volume through the interchange does not make any of things you mention better. It just results in more traffic. We don't need more traffic on the roads in that area.

I don't think anyone is trying to increase car volume. Just to properly move the cars already there every single day. The problem already exists. And ART is going to only barely scratch the surface of needed improvements. It's also not funded, nor guaranteed to ever happen. Lastly, how would ART work on a road that is already stopped?

I wonder exactly how many people aren't out driving solely because traffic is bad at certain times.