I-840, I-65,I-40 and I-24 discussions for double decker freeways in Tennessee

[bing101]

https://www.tennessean.com/story/news/politics/tn-elections/2018/05/08/diane-black-proposes-double-stacked-interstates-840-extension-after-nashville-transit-defeat/591936002/

According to the article there is talks to make I-840 into a double Decker freeway.

[bing101]

Also I-40, I-65 and I-24 are mentioned for a proposed double Decker freeway in the Nashville area.

This after the Mass Transit vote was defeated in Tennessee.

[oscar]

https://www.tennessean.com/story/news/politics/tn-elections/2018/05/08/diane-black-proposes-double-stacked-interstates-840-extension-after-nashville-transit-defeat/591936002/

According to the article there is talks to make I-840 into a double Decker freeway.

Where in the article? The downtown parts of I-24, I-40, and I-65 were mentioned for double-decking, but only mention of I-840 was for completing the never-built part north of I-40.

Double-decking a rural freeway like I-840 would be daffy.

[sparker]

I talked about this a couple of years ago, but if the east side of I-840 were to be extended north to re-intersect I-65 near the KY state line, that would provide a bypass useful for I-65 traffic as well as the current 840 bypass for I-40.  Of course I-24 traffic could also use that to get to and from northward I-65; extending the bypass back to I-24 NW of Nashville may not be necessary considering the lower usage of that corridor.  Because of the NE angle I-65 takes north of Nashville, extending I-840 in that fashion would require less mileage to accomplish more functionality.

[hbelkins]

Weren't the improvements to TN 109, and the new exit just south of the state line, supposed to work in lieu of an extension of 840?

[sparker]

Weren't the improvements to TN 109, and the new exit just south of the state line, supposed to work in lieu of an extension of 840?

TN 109 spot upgrades and an interchange relocation may have been a cheaper way to go than an actual facility extension, but those would be more for the benefit of local traffic than an actual functional bypass for I-65.  Unless it's peak commute times -- and the driver is familiar with the combination 840/109 route and doesn't mind schlepping through Gallatin & Portland, it's not really an effective bypass; there are too many ducks to line up in that particular row.  It's not as if the full 840 loop needs to be completed -- but a limited-access facility between I-40 and I-65 would certainly help with the regional traffic flow -- as long as any local temptation to site development along that corridor is avoided. 

[Revive 755]

^ Would using TN 25 between I-65 and TN 109 be any better?  Looks like it would be longer, but you'd bypass Portland.

Since these proposals are coming from a gubernatorial candidate, maybe/hopefully the 475 bypass for Knoxville will start showing signs of life as well.

[sparker]

^ Would using TN 25 between I-65 and TN 109 be any better?  Looks like it would be longer, but you'd bypass Portland.

Since these proposals are coming from a gubernatorial candidate, maybe/hopefully the 475 bypass for Knoxville will start showing signs of life as well.

The point I was attempting to make was that the whole purpose of regional improvements in or around Nashville would be to expedite traffic -- particularly through traffic -- past the city-center congestion points.  A real N-S bypass -- preferably Interstate-grade, but at least to the level of a controlled-access expressway -- extending north from the east I-40/840 junction to I-65 -- and noted as a bypass on BGS's at both I-65 intersections, would at least have the potential to reroute I-65 traffic onto itself, pulling it off the current in-town mainline with its convolutions and TOTSO's.  No cobbled-together string of surface roads can offer that level of service.  If massive downtown structures are being considered, something like this bypass concept might be an alternative that would produce similar results absent the service interruptions that extensive double-decking would entail. 

Re the I-475 Knoxville bypass revival:  when the Knoxville situation reaches the "critical mass" of Nashville traffic, then it may be revisited, providing the issues that plagued that concept a decade or so ago can be resolved or mitigated. 

[hbelkins]

I've never been on the I-40/I-75 concurrency that it wasn't a cluster foxtrot.

I think Tennessee needs to address the narrowing of I-75 to a single lane at the ramp that it uses to enter the I-640 concurrency. I've seen traffic backed up to use that ramp to the point where it would probably be faster to stay on I-275 (former I-75) to access I-40.

[SteveG1988]

I've never been on the I-40/I-75 concurrency that it wasn't a cluster foxtrot.

I think Tennessee needs to address the narrowing of I-75 to a single lane at the ramp that it uses to enter the I-640 concurrency. I've seen traffic backed up to use that ramp to the point where it would probably be faster to stay on I-275 (former I-75) to access I-40.

I've done that in the truck.

Nashville needs a north/south bypass, it sucks that all traffic has to go through the city core if they want to stay on freeways.

If they needed to they could just build it as the Tennessee Tennpike and toll the crap out of it to get it built.

[Henry]

This is pure madness! First I-35 between San Antonio and Austin, and now this? I used to think double-decker freeways were dead, thanks to the demolition of several on the West Coast (I-880, the Embarcadero Freeway and WA 99/Alaskan Way come to mind), but apparently the revival is coming.

[The Ghostbuster]

Although I've never been to Nashville, wouldn't double-decking be overkill? Or is double-decking an idea that seriously merits consideration in the Nashville area?

[froggie]

Those promoting double-decking are looking at it almost purely from a capacity standpoint.  There are several factors that are often ignored, especially by politicians pandering for votes such as this Tennessee lady.  She either doesn't realize or doesn't care that a combination of cost, noise, environmental, and off-Interstate traffic issues are going to quickly put an end to her "plan".

[Anthony_JK]

From what I've seen of the ROW of all these Nashville freeways, it would be darn near impossible to double deck them anyway.

Plus, how would she pay for all this? Tolls everywhere??

[ATLRedSoxFan]

The tophagrahy around there at the very least would make it extremely difficult, but not impossible, but would probably take as long as Boston's Big Dig along with cost overruns. They have bigger fish to fry including upgrading I-40 West to at least 840. Also extending the NE sector of 840 back to I-65 does make sense, but that seems more like a wish bucket/wish than reality. They are barely figuring out the I-69/269 situation including funding for I-69, so don't see any urgency on this Pipedream.

Having said that, Nashville has a couple balls in the air at the moment. The city just landed/reinstated their transatlantic air link with British Airways recent start with service to London, replacing what service American Airlines had when they had a hub at BNA years ago. (Congratulations by the way!) Along with this, on the table is a total renovation of the terminal with the addition of an IAB(Internationa Arrivals Building) to accommodate that flight along with other hopeful international service. Add to that, an onsite hotel and light rail from the city center and you have quite an untertaking in itself. And that's gonna be pretty pricy even with Davividson County/ City of Nashville on the hook, bonds are somehow going to appear from the state.

The only double-decking that would make sense is where the interstates share concurrencies, if nothing else to aid with transitioning ramps. The reason I contend it's a lofty goal or Pipedream is the example I pointed out with I-69, not to mention, when I lived in Knoxville, how long it took for TN to build I-140, even though the bridge across FT. Loudon Lake had been finished for years, it just sat there. Just my two cents.

[ukfan758]

I'm all for significant freeway improvements but this is insane. Yes it will boost capacity but construction would be an absolute nightmare, the costs would be absurd, and so would maintenance costs years down the road. 

[jpi]

Weren't the improvements to TN 109, and the new exit just south of the state line, supposed to work in lieu of an extension of 840?

Yes, along with improvements to Hartsville Pike (TN 141) and TN 10 and some other smaller projects I can't remember off hand, personally I think they should extend the stub end at I-40 near Dickson all the way north to I-24 past Ashland City and come out just south of Clarksville, this would make a very nice by-pass for I-24 traffic and I-65 traffic utilize the TN 109\ I-840.

I-840 has had a NIG increase in traffic since it was "promoted" to interstate status but is still fairly quiet between US 31 and I-40 on the Dickson side. And no 840 does not need double decked, if anything it could use a decent rest area on either side and some improved signage for control city distance.