Atlanta intersections that should be upgraded to interchanges

[Tom958]

Sugarloaf Parkway @ Lawrenceville Highway (US 29) in Gwinnett County.  I lived near that intersection for 26 years.  It is the intersection from hell!

Yes, Having lived a year off Sugarloaf and Five Forks/Trickum, that intersection is FUBAR. Sugarloaf and Scenic Highway should be 6-8 lanes all throughout Gwinnett, IMO

I'm interested in taking a stab at this redesigning this intersection, can someone elaborate on the pressing issues?

It's pretty well just capacity. If Sugarloaf was six lanes and had dual left turn lanes at that intersection, it'd likely be enough. The directional split on Sugarloaf is severe, and giving it as much green time as possible creates congestion on US 29, too. The root of the problem is that at the time of construction, Sugarloaf was (and probably still is) classified as a principal arterial with six lanes, a 60 mph design speed, and a 120 foot right-of-way, but doing that would've required total takes of the single-family homes lining one side of what was then two-lane Davis Mill Road between US 29 and  Old Norcross Road. Especially in the face of massive cost escalation for road works in the nineties, they crammed four lanes into the existing corridor with minimal ROW acquisition, which is how it remains today.

This intersection is about two miles from my house, where I've lived since 1988, so I've thought about it a lot. It's tempting to imagine an interchange there, but I don't think it'd be a good idea to actually build one. As a matter of fact, at the time that part of Sugarloaf Parkway was built, the plan was to extend Riverside Parkway southward from its current terminus at Old Norcross Road along Monfort Road to Sugarloaf just west of US 29. Even then, AFAIK no interchange was ever proposed there.

[RoadWarrior56]

I think Tom958 pretty much sums the issues up.  And yes, old Davis Mill Road was a very narrow windy two-lane county road that was "repurposed" into Sugarloaf Parkway.  There is just too much demand on multiple approaches at certain times of the day, so if you provide more green time to one approach, you make the others even worse.  Also, originally Sugarloaf Parkway was never expected to have the kind of traffic volumes on it that it does today.  Multiple intersections have had left-turn bays lengthened, etc.  To add the icing on the cake at Sugarloaf @ US 29, there is a heavy right-turn movement from EB(SB) Sugarloaf Parkway to SB(WB) US 29.  The right-turn lane is very short, presumably due to the existence of underground storage tanks for a preexisting Shell station that sits on that corner.  The de-facto right-turn movement is through the pot-holed filled parking lot behind the Shell station, which is mostly empty.  On top of everything else, the intersection has a significant skew.  I used that intersection on a regular basis between 1996 and 2022.  One of the best things of having moved, is that I now do NOT have to figure out how to avoid it at certain hours.

[jakeroot]

Sugarloaf Parkway @ Lawrenceville Highway (US 29) in Gwinnett County.  I lived near that intersection for 26 years.  It is the intersection from hell!

Yes, Having lived a year off Sugarloaf and Five Forks/Trickum, that intersection is FUBAR. Sugarloaf and Scenic Highway should be 6-8 lanes all throughout Gwinnett, IMO

I'm interested in taking a stab at this redesigning this intersection, can someone elaborate on the pressing issues?

It's pretty well just capacity. If Sugarloaf was six lanes and had dual left turn lanes at that intersection, it'd likely be enough. The directional split on Sugarloaf is severe, and giving it as much green time as possible creates congestion on US 29, too. The root of the problem is that at the time of construction, Sugarloaf was (and probably still is) classified as a principal arterial with six lanes, a 60 mph design speed, and a 120 foot right-of-way, but doing that would've required total takes of the single-family homes lining one side of what was then two-lane Davis Mill Road between US 29 and  Old Norcross Road. Especially in the face of massive cost escalation for road works in the nineties, they crammed four lanes into the existing corridor with minimal ROW acquisition, which is how it remains today.

This intersection is about two miles from my house, where I've lived since 1988, so I've thought about it a lot. It's tempting to imagine an interchange there, but I don't think it'd be a good idea to actually build one. As a matter of fact, at the time that part of Sugarloaf Parkway was built, the plan was to extend Riverside Parkway southward from its current terminus at Old Norcross Road along Monfort Road to Sugarloaf just west of US 29. Even then, AFAIK no interchange was ever proposed there.

I think Tom958 pretty much sums the issues up.  And yes, old Davis Mill Road was a very narrow windy two-lane county road that was "repurposed" into Sugarloaf Parkway.  There is just too much demand on multiple approaches at certain times of the day, so if you provide more green time to one approach, you make the others even worse.  Also, originally Sugarloaf Parkway was never expected to have the kind of traffic volumes on it that it does today.  Multiple intersections have had left-turn bays lengthened, etc.  To add the icing on the cake at Sugarloaf @ US 29, there is a heavy right-turn movement from EB(SB) Sugarloaf Parkway to SB(WB) US 29.  The right-turn lane is very short, presumably due to the existence of underground storage tanks for a preexisting Shell station that sits on that corner.  The de-facto right-turn movement is through the pot-holed filled parking lot behind the Shell station, which is mostly empty.  On top of everything else, the intersection has a significant skew.  I used that intersection on a regular basis between 1996 and 2022.  One of the best things of having moved, is that I now do NOT have to figure out how to avoid it at certain hours.

Sorry for the delay here. I decided to take a stab at redesigning this whole triangle of roadways. I've posted it over in the "Redesigning Intersections" thread if you want to check it out:

https://www.aaroads.com/forum/index.php?topic=7062.msg2810929#msg2810929

Decided to give a go at the Sugarloaf Pkwy / Lawrenceville Hwy intersection triangle in Lawrenceville, GA.

Here is the original location: https://www.google.com/maps/@33.9371798,-84.0299238,825m/data=!3m1!1e3

My comments were inspired by posts in the "Atlanta intersections that should be upgraded to interchanges" thread.

Just did this one by hand. Not totally to scale. Definitely looking for feedback. This diagram does not show anything but road shapes and general flow, the final design would obviously have plenty of pedestrian and cycle facilities (ideally grade-separated).


LawrencevilleGA Int Redesign V2 by Jacob Root, on Flickr

[Tom958]

Just did this one by hand. Not totally to scale. Definitely looking for feedback. This diagram does not show anything but road shapes and general flow, the final design would obviously have plenty of pedestrian and cycle facilities (ideally grade-separated).


LawrencevilleGA Int Redesign V2 by Jacob Root, on Flickr

Two weeks later... I said initially that an interchange wasn't necessary, but I guess I could elaborate...

You would've had little way of knowing, but there's a hillcrest on Sugarloaf at the Montfort road connector, and on US 29 there's a substantial gradient uphill from the railroad bridge toward Sugarloaf, as seen in this view. If there were to be a grade separation at 29 and Sugarloaf, Sugarloaf would need to go over 29, not under. Doing this would require raising and likely razing and replacing Sugarloaf's bridge over the railroad. Of course, the time to have done this would've been during the initial construction. Now, raising the railroad bridge without closing Sugarloaf during construction would require building a new bridge beside the old and pretty much dictating the same thing for the bridge over 29, too. By the time you've done that, you've pretty well obliterated the whole area, so there's no reason to nickel-and-dime the interchange footprint.

Sorry. 

Speaking of nickel-and-diming the footprint, why the RTO interchange ramps in your scheme? Why not just draw a couple of SPUIs?

[jakeroot]

You would've had little way of knowing, but there's a hillcrest on Sugarloaf at the Montfort road connector, and on US 29 there's a substantial gradient uphill from the railroad bridge toward Sugarloaf, as seen in this view. If there were to be a grade separation at 29 and Sugarloaf, Sugarloaf would need to go over 29, not under. Doing this would require raising and likely razing and replacing Sugarloaf's bridge over the railroad. Of course, the time to have done this would've been during the initial construction. Now, raising the railroad bridge without closing Sugarloaf during construction would require building a new bridge beside the old and pretty much dictating the same thing for the bridge over 29, too. By the time you've done that, you've pretty well obliterated the whole area, so there's no reason to nickel-and-dime the interchange footprint.

Sorry. 

Speaking of nickel-and-diming the footprint, why the RTO interchange ramps in your scheme? Why not just draw a couple of SPUIs?

No need to apologize, I appreciate the very detailed feedback! This was something I more or less did in an afternoon thinking about how flow could potentially work across the area, so there was certainly not a lot of attention paid to geography. Apart from the rail line...sort of.

Regarding the interchange ramps, I was going for a design that had various movements at each junction, without each junction being redundant with the other. Eg, I didn't see a reason to design left turns from Lawrenceville Hwy to Sugarloaf Pkwy, when Lawrenceville-Suwanee Road could handle that movement. Likewise for the movement from southbound Sugarloaf, using the southern intersection to handle that left turn.

I could have just put SPUIs at each intersection, but like I said, I wanted a design where traffic was distributed across the three major intersections.

[RoadWarrior56]

Boulevard @ Freedom Pkwy used to be an interchange, when Freedom Pkwy was the I-485 stub.  It was converted to an at-grade interchange as part of the Freedom Pkwy compromise.  The I-485/Presidential Pkwy/Freedom Pkwy saga has an interesting history that goes back many decades.

[Tomahawkin]

I go through that Bleeped up intersection every Thursday for work. I bleeping hate that intersection with a passion. The homeless people there and the MF'ERS on the scooters when it's warm make it annoying and dangerous at the same time. With that in mind all of Ponce is FUBAR in East Atlanta

[Tomahawkin]

Add LaVista Rd at 285 to the list. I forgot how bad that interchange is during rush hour. The Bridge needs to be rebuilt. Hopefully that happens in the next 3 years when the 285 toll lanes are built??? The traffic at that interchange gets clogged anytime there is a wreck on 285. Ditto for a lot of surface streets that traverse 285

[Georgia Guardrail]

Boulevard @ Freedom Pkwy used to be an interchange, when Freedom Pkwy was the I-485 stub.  It was converted to an at-grade interchange as part of the Freedom Pkwy compromise.  The I-485/Presidential Pkwy/Freedom Pkwy saga has an interesting history that goes back many decades.

That's interesting!  What kind of interchange was it?  Anyone have an old satellite view of this?

[Tom958]

Boulevard @ Freedom Pkwy used to be an interchange, when Freedom Pkwy was the I-485 stub.  It was converted to an at-grade interchange as part of the Freedom Pkwy compromise.  The I-485/Presidential Pkwy/Freedom Pkwy saga has an interesting history that goes back many decades.

That's interesting!  What kind of interchange was it?  Anyone have an old satellite view of this?

https://www.historicaerials.com/location/33.75929786992031/-84.37016755762872/1981/16

Calling it an interchange was a bit generous. It amounted to commandeering the severed Howell Street for use as slip ramps, plus there was an onramp toward downtown from Boulevard.