AL: US31/280 Broken Concurrency in Birmingham

[theFXexpert]

US31 and US280 appear to have a broken concurrency in Birmingham, AL between I-20/I-59 and 2ndAveN caused by US31 having an additional waypoint at Carraway Blvd.

[froggie]

Using this thread as a placeholder as I evaluate how to handle 31 and 280, since 280 follows the "mainline" to 20/59 while 31 goes at-grade at Carraway (hence why 31 has a point there but 280 didn't).  Technically speaking, I may also need to add a point to 280 at 5th/6th that won't exist on 31 as there's a half-interchange at 5th/6th that connects to 280 before it ends at 20/59 but does not connect to 31.

[si404]

Does US31 directly interchange with the interstates? Seems to me like the route between them is along the non-concurrent 280 or some surface road wiggling about.

If it's indirect, add the point for the interchange at 5th to both routes, as concurrency split where 280 turns off mainline while 31 stays on it.

[theFXexpert]

For what it's worth, the AASHTO archive for the US31 reroute and US280 extension onto the Stephens Expressway in 1989 both appear to utilize the same control points with identical mileage between them. The last control point for both applications is "Jct I-20 & I-59"

https://grmservices.grmims.com/vsearch/portal/public/na4/aashto/default

The ramps to/from the Stephens Expressway (US31/280) participate in this junction with I-20/59 and are ramps; not a mainline.
https://www.dot.state.al.us/maps/pdf/surveyMapping/HFC/regec/37-BirminghamUrban.pdf
https://www.dot.state.al.us/maps/pdf/surveyMapping/HFC/regec/37-BirminghamMPO.pdf

[froggie]

^ Do those ALDOT links actually work for others?  I have been unable to get to any of ALDOT's webpages in a number of weeks and I'm not sure why...this is why I haven't done anything further on the issue this month.

[formulanone]

^ Do those ALDOT links actually work for others?  I have been unable to get to any of ALDOT's webpages in a number of weeks and I'm not sure why...this is why I haven't done anything further on the issue this month.

It loaded for me, though it's an 8 MB pdf (and 4 MB for the MPO file). ALDOT does seem a bit slow, though hotel internet is rarely superb for that kind of stuff.

[rickmastfan67]

Yep, those PDF links are working just fine for me Froggie.

Sounds like your ISP has an issue.  Maybe manually change your DNS servers?  I'm using 1.1.1.1 & 1.0.0.1 for mine.

[froggie]

Tried changing DNS and still no luck.

[rickmastfan67]

Tried changing DNS and still no luck.

Then contact your ISP about this issue.  They might need to fix something.

[froggie]

Definitely an ISP issue...was able to access the ALDOT websites on my iPad via LTE.

Regarding the OP, and after looking at the maps FXpert posted, ALDOT Milepost Maps, aerial imagery, and GMSV, here's what I'm going to do, which may seem a little weird to some but bear with me:

• Add a point where the ramps to/from I-20/59 split...this is where, per signage, US 280 "splits" from US 31.
• Include the CarrBlvd point on US 280, but make it a hidden point.  This is because, as noted above, signage indicates US 280 follows the ramps to I-20/59 and not the US 31 "mainline".
• Add a point at 5th/6th that is visible on the US 280 list but hidden on US 31 (as this access point is only via US 280.

That should take care of the broken concurrency.

On a related note, I'll have to rename 125A on I-20/59 to 124D, and star out 125B which no longer exists...125B was previously the direct ramps to/from 22nd St.  They were taken out with the viaduct replacement.
[/list]

[rickmastfan67]

• Include the CarrBlvd point on US 280, but make it a hidden point.  This is because, as noted above, signage indicates US 280 follows the ramps to I-20/59 and not the US 31 "mainline".

That will probably throw up an error on the datacheck page.  Just like how MN-119 currently has one due to a point being hidden when it shouldn't be.

Code: [Select]

mn.mn040;MN119_N;;;VISIBLE_HIDDEN_COLOC;mn.mn119@+MN40

[vdeane]

Looking at those AASHTO documents, it appears that US 280 was intended to end at I-20/59, whereas US 31 continues north, with the realignment ending at the viaduct.  As such, US 280 would follow the ramps to I-20/59, whereas US 31 would take the ramps to the surface roads; the same label would thus not signify them taking the same road (Alabama probably figured "close enough").  US 31 and US 280 are on physically separate road; elsewhere on the site where this happens, concurrences are purposefully broken (see A-440/QC 335, or I-80/I-29 in Iowa, for example).  As such, I am staunchly opposed to the idea of having these marked concurrent, as it is in direct opposition to all prior precedent on TM, and not all users would even want them both marked clinched if they only have one.

In fact, they might have actually been mistakenly marked concurrent at one time and then later had the concurrency broken; the CarrBlvd point didn't exist when I was there in 2016.

[theFXexpert]

That sounds reasonable to me.

[froggie]

• Include the CarrBlvd point on US 280, but make it a hidden point.  This is because, as noted above, signage indicates US 280 follows the ramps to I-20/59 and not the US 31 "mainline".

That will probably throw up an error on the datacheck page.  Just like how MN-119 currently has one due to a point being hidden when it shouldn't be.

Code: [Select]

mn.mn040;MN119_N;;;VISIBLE_HIDDEN_COLOC;mn.mn119@+MN40

Could easily be listed as a false positive, given the circumstances.  I went the route I did because there are indications (specifically signage, though the AASHTO documents seem to indicate such too) that US 280 takes the ramps to 20/59.  On the same token, ALDOT maps indicate a concurrency up to 20/59.  I was trying to marry the two ideas, further considering that there are some access points within the "concurrency" that are accessible to one but not the other.

I'm open to other suggestions.  I may need to revise the US 31 points anyway since there is officially and physically no direct connection between 31 and 20/59.

[vdeane]

If US 280 takes the ramps, wouldn't the current marking be inconsistent with how similar cases are handled elsewhere in TM?  Not sure what to make of ALDOT's maps; I doubt they had TM in mind when they made them.