Chattanooga I-24 Improvements

[Brian556]

Article came out today in the Chattanoogan, saying improvements to I-24 at Moccasin Bend could begin next year. Article also has a nice historic photo of the Tennessee River being shifted over so that I-24 could be constructed.

[US 89]

I hope those improvements include another lane in each direction. I have gone through that area several times and never has there not been some sort of congestion.

[Georgia]

That article also says both phases(dividing line is Browns Ferry Rd) are just now in preliminary engineering phase so I would be interested to see when in '24 this project would begin.  It is widening 24 from TN/GA State line to US 27.

https://www.chattanoogan.com/2023/1/17/462540/Widening-Of-I-24-Around-Moccasin-Bend.aspx

[wriddle082]

I want to say the median in the Mocassin Bend stretch is just wide enough to accommodate at least one extra lane in each direction, but it's hard to tell because the carriageway elevations are offset, with the westbound lanes next to the river being a few feet lower than the eastbound lanes.  So there will definitely be a tall retaining wall on the left shoulder of the westbound lanes, and the right shoulder may very well have a retaining wall in the river.

[froggie]

^ I want to say we had a thread discussing this recently.  Preliminary plans are online and I recall looking at them.  The plan is to squeeze between the existing lanes and the railroad...there isn't enough room in the median so the widening will extend some towards the railroad.  IIRC they are not going to extend any widening on the river side.

[Georgia]

Drove on that section of 24 each of the last 2 days; I think retaining walls/medians between the east and westbound lanes will be critical, also that the sides are going to have be kept at differing heights. 

there is a little bit of room on the eastbound side before you run into the railroad fence but most of it will come from the westbound lanes side I guess. 

[milbfan]

If money, time, and logistics weren't major issues (lol), I would say turn that part of I-24 (at least near Browns Ferry to downtown) into a double-decker, with however many lanes to accommodate each direction.  EB would take top or bottom, with WB taking the other.

But like I said, logistics, mainly anyone coming from Nashville, going SE to Nooga/ATL/75 South would make this approach problematic.

[sprjus4]

^ Will the widening include I-24 north of I-59 in the Georgia portion?

Dropping from 3 to 2 lanes before that split would seem quite problematic with traffic. Does Georgia intend to widen their small portion to allow the lane split to properly make it to I-59?

[Great Lakes Roads]

^ Will the widening include I-24 north of I-59 in the Georgia portion?

Dropping from 3 to 2 lanes before that split would seem quite problematic with traffic. Does Georgia intend to widen their small portion to allow the lane split to properly make it to I-59?

Yes, and that portion of the widening project is owned by GDOT since TDOT isn't involved in that stretch...

[wriddle082]

^ Will the widening include I-24 north of I-59 in the Georgia portion?

Dropping from 3 to 2 lanes before that split would seem quite problematic with traffic. Does Georgia intend to widen their small portion to allow the lane split to properly make it to I-59?

Yes, and that portion of the widening project is owned by GDOT since TDOT isn't involved in that stretch...

I'm sure GDOT will coordinate with TDOT to ensure the widening of each states' sections occurs simultaneously.  GDOT is currently working with SCDOT to widen I-20 from GA Exit 200 to SC Exit 1, including a brand new Savannah River crossing.

[Tom958]

IMO, a case could've been made for building the Moccasin Bend stretch as six lanes initially, given the difficulty of widening it under traffic. had that been done, the rest of the six laning to I-59 would likely have been done in the nineties.

I want to say the median in the Mocassin Bend stretch is just wide enough to accommodate at least one extra lane in each direction, but it's hard to tell because the carriageway elevations are offset, with the westbound lanes next to the river being a few feet lower than the eastbound lanes.  So there will definitely be a tall retaining wall on the left shoulder of the westbound lanes, and the right shoulder may very well have a retaining wall in the river.

Google Maps shows that the median is about 38 feet, which is nominally enough for two more lanes, though with a substandard left shoulder width.

^ I want to say we had a thread discussing this recently.  Preliminary plans are online and I recall looking at them.  The plan is to squeeze between the existing lanes and the railroad...there isn't enough room in the median so the widening will extend some towards the railroad.  IIRC they are not going to extend any widening on the river side

I'd say add an eastbound lane on the railroad side and a westbound lane in the median, with full-width left shoulders in each direction. 

I'm gonna try to find those plans now.

[froggie]

I'm gonna try to find those plans now.

Ask and ye shall receive...

[Tom958]

I'm gonna try to find those plans now.

Ask and ye shall receive...

Thanks! I was pleasantly surprised to see that the Georgia portions are included, too.

Not that it was a particularly brilliant deduction, but it appears that I was right: through Mocassin Bend, a third westbound lane and two twelve-foot left shoulders will replace the median, and the third eastbound lane and its right shoulder will be added to the south, away from the river. As you said, there'll be no further widening into the river. Oddly, though, the only cross sections I see are for the less-interesting sections to the west, with both of the added lanes in the median. 

[sprjus4]

From those plans, here is the bend portion of the widening.

The remainder not pictured to the west is standard median widening with full left shoulders, extending into Georgia to I-59.

[ChiMilNet]

This really needs to happen! Having driven through this stretch a few times this year already, twice I have had to detour off I-24 due to some accident in this stretch. The amount of truck traffic alone is just amazing. Honestly, I-24 b/w Chattanooga and Nashville in general could stand a number of upgrades and lane additions, though ones I am sure are ridiculously expensive (looking at you Monteagle). This definitely will be step in the right direction, though.

[SilverMustang2011]

This really needs to happen! Having driven through this stretch a few times this year already, twice I have had to detour off I-24 due to some accident in this stretch. The amount of truck traffic alone is just amazing. Honestly, I-24 b/w Chattanooga and Nashville in general could stand a number of upgrades and lane additions, though ones I am sure are ridiculously expensive (looking at you Monteagle). This definitely will be step in the right direction, though.

In a perfect world I-24 is at least 6 lanes between Chattanooga and Nashville. I've only driven it twice, but based on all the growth in Nashville, Atlanta being Atlanta, and the commercial traffic that uses the road, it'll need to happen sooner or later. Going East from Nashville, I think the section between Murfreesboro and MM 130 is pretty easy to upgrade since it's mostly a wide median and rolling hills, but I really don't know how you could widen the following climb up to Monteagle with the existing space and tight curves. The section between Exit 158 and the I-59 interchange would be a pain too since the bridge over the Tennessee River would need to be widened or replaced and there's more hilly terrain beyond that, albeit easier terrain to work with than Monteagle.

[pianocello]

This really needs to happen! Having driven through this stretch a few times this year already, twice I have had to detour off I-24 due to some accident in this stretch. The amount of truck traffic alone is just amazing. Honestly, I-24 b/w Chattanooga and Nashville in general could stand a number of upgrades and lane additions, though ones I am sure are ridiculously expensive (looking at you Monteagle). This definitely will be step in the right direction, though.

If anywhere in the US was a good candidate for a base tunnel like some in the Alps, Monteagle would be it. The elevations at the bottom of the hill on both sides aren't too far from each other.

Of course, it would be completely infeasible for a multitude of reasons.

[civilengineeringnerd]

This really needs to happen! Having driven through this stretch a few times this year already, twice I have had to detour off I-24 due to some accident in this stretch. The amount of truck traffic alone is just amazing. Honestly, I-24 b/w Chattanooga and Nashville in general could stand a number of upgrades and lane additions, though ones I am sure are ridiculously expensive (looking at you Monteagle). This definitely will be step in the right direction, though.

If anywhere in the US was a good candidate for a base tunnel like some in the Alps, Monteagle would be it. The elevations at the bottom of the hill on both sides aren't too far from each other.

Of course, it would be completely infeasible for a multitude of reasons.

why is it infeasible?

[triplemultiplex]

Because we forgot how to build tunnels in America without breaking the bank.

[The Ghostbuster]

The United States should build more tunnels like the Big Dig and the Alaskan Way Viaduct Tunnel replacement. If they can do it overseas, they most certainly can find a way to do it here.

[RoadWarrior56]

As a reply to the previous post, this not the country I grew up in anymore.  Large public works projects often take years to get approved and to get permits, and NIMBY's and other special interests reflexively oppose everything and cause years of litigation.  Don't get me started on the environmental lobby.  It is a good thing the Interstate System was constructed when it was.  If it were proposed now, it would take at least 100 years to construct and cause 10-20 time more on real dollars, and probably up to half of it would not be approved anyway.  I hate to sound so cynical, but IMO, that is the reality we live in.

[Rothman]

As a reply to the previous post, this not the country I grew up in anymore.  Large public works projects often take years to get approved and to get permits, and NIMBY's and other special interests reflexively oppose everything and cause years of litigation.  Don't get me started on the environmental lobby.  It is a good thing the Interstate System was constructed when it was.  If it were proposed now, it would take at least 100 years to construct and cause 10-20 time more on real dollars, and probably up to half of it would not be approved anyway.  I hate to sound so cynical, but IMO, that is the reality we live in.

The NEPA process is not all negative.  Had it existed when the IHS was conceived, the system actually might have been built better in much more helpful locations due to increased public input.

[sprjus4]

As a reply to the previous post, this not the country I grew up in anymore.  Large public works projects often take years to get approved and to get permits, and NIMBY's and other special interests reflexively oppose everything and cause years of litigation.  Don't get me started on the environmental lobby.  It is a good thing the Interstate System was constructed when it was.  If it were proposed now, it would take at least 100 years to construct and cause 10-20 time more on real dollars, and probably up to half of it would not be approved anyway.  I hate to sound so cynical, but IMO, that is the reality we live in.

The NEPA process is not all negative.  Had it existed when the IHS was conceived, the system actually might have been built better in much more helpful locations due to increased public input.

True - but many sections probably would not have been built where necessary due to impacts unfortunately required - and would also take 50-100 years.

[RoadWarrior56]

In a reply to the replies to my previous post, I agree that NEPA is not negative, at least as it was conceived.  The problem with it is that it is often abused as a vehicle for delay and litigation, and often for reasons that have nothing to do with environmental issues.

[US 89]

The NEPA process is not all negative.  Had it existed when the IHS was conceived, the system actually might have been built better in much more helpful locations due to increased public input.

That assumes your public input doesn’t consist entirely of unhelpful litigious NIMBYs and hardcore environmentalists, who tend to drown out other voices in these types of spaces. Agreed that NEPA isn’t a total negative, but because it’s so easy to challenge a big project, it usually winds up being a losing situation for everyone except the lawyers.