Same-direction through lanes (on a freeway) bifurcated around an obstacle

[briantroutman]

Sometimes, freeways are routed through or underneath existing structures that constrict their possible widening–such as this 19th century stone arch railroad bridge spanning both I-76 and the Schuylkill River in Philadelphia.

It has occurred to me that if, for instance, PennDOT wanted to widen the westbound carriageway to six lanes here (to make nine lanes total) without altering the railroad bridge, it would need to split the westbound lanes (three and three) approaching the bridge and then route them through two separate arches. Or similarly, if the PTC constructed a third (or fourth) bore at the tunnel locations to permit six or more continuous through lanes, it would need to somehow split the lanes as they approach the tunnel and then direct them through separate tubes.

There are numerous instances where through lanes are split to divide different types of traffic (such as the separate "cars"  and "trucks"  carriageways of the New Jersey Turnpike or the "local"  and "express"  lanes of I-270 in Maryland), but are there any instances where the full-speed through lanes of a freeway are split to get around an obstacle without any logical separation of the traffic with regard to classification (trucks vs. cars) or destination (local vs. express, diverging routes, etc.)?

Other than construction zones–where I've occasionally seen such a split with some kind of ALL LANES THROUGH signage–the only such example I can think of is at the Fort McHenry Tunnel in Baltimore. And that example is qualified somewhat by the fact that there is a toll plaza spanning the southbound lanes (and therefore only the E-ZPass-only lanes proceed through at full speed), and even in the northbound direction, there is at least some semblance of logic to the separation with E-ZPass customers being directed toward the left side of the split.

Are there any other (and ideally, better) examples of such a split with no logical separation of the types or destination of traffic? And if not, what do you think signage approaching such a split should look like? Somehow, I doubt that a modified W6-1-type sign, as Maryland uses at Fort McHenry (in addition to other signage) would suffice on its own.

[Joe The Dragon]

Kind of on I-88 (IL)
https://goo.gl/maps/ATmfXLG6n5oHsBz7A

[webny99]

Kind of on I-88 (IL)
https://goo.gl/maps/ATmfXLG6n5oHsBz7A

If that counts, there's quite a few similar situations around.
I'm pretty sure I've seen a legitimate example or two, but can't think of where.

[ErmineNotyours]

I-90 Eastbound, Mount Baker Tunnel, Seattle.  Advance sign.  Secondary sign.  Actual split.

Reason: reuse of original 1940 four lane US 10 tunnel.

The following doesn't count because it's an HOV lane and different traffic, but it's only a brief separation, and it's the same idea: continued use of an existing structure.  HOV split on I-5.

[ErmineNotyours]

There have to be numerous examples (non-freeway) of agencies continuing to use truss and other bridges.  Portland, Hawthorne Bridge.  Surrey, BC Nicomekl River Bridge.

[jeffandnicole]

I-95 on the Capital Beltway in VA/DC/MD. While it's signed Thru and Local, the local lanes seem to often be faster (possibly due to the large number of motorists not familiar with the area and driving slower than necessary in the thru lanes).

the only such example I can think of is at the Fort McHenry Tunnel in Baltimore. And that example is qualified somewhat by the fact that there is a toll plaza spanning the southbound lanes (and therefore only the E-ZPass-only lanes proceed through at full speed), and even in the northbound direction, there is at least some semblance of logic to the separation with E-ZPass customers being directed toward the left side of the split.

It may be important to note that EZ Pass came long after the tunnels and toll plazas were built.  The sole EZ Pass "Express" lane was the left lane of each toll plaza, which had been signed at 30 mph much of its life (well below full speed at nearly half of the regular speed limit, thus my using Express in quotes, as there was nothing express about it). This lane was subject to congestion as motorists really adhered to the 30 mph limit. And this lane, by virtue of the lane markings, was continuous thru the entire tunnel as well.

Southbound motorists with any clue would avoid that sole "express" lane, go thru a traditional toll lane signed for just EZ Pass, and then have 3 tunnel lanes to choose from.  Likewise, NB drivers could stay out of the left lane, use any of the other 3 lanes, and have numerous options of mostly empty EZ Pass lanes when they exited the tunnel.

[mapman]

CA 24 when approaching the Caldecott Tunnel(s) in Oakland, CA.  Traffic is split between four separate tunnels (two eastbound, two westbound).

[roadman65]

Grand Central Parkway in Flushing, NY has one W Bound where thee route splits around the two arched overpasses.  The EB side goes under one wider more modern bridge.

[deathtopumpkins]

I-10 in San Antonio splits into an upper and lower level: https://goo.gl/maps/wiXywUxQLFW8QbYs6
In the other direction, the levels are signed with different destinations in order to reduce instances of people quickly cutting across multiple lanes after the levels rejoin, but both levels are I-10.

I-35 also splits into an upper and lower level TWICE in San Antonio: e.g. https://goo.gl/maps/KeYz5WLW28DU4tyYA
In both cases the levels are signed with different destinations but both are I-35 and you can use either.

I-35 splits again in Austin: https://goo.gl/maps/iwkbbkeRhzTjCwBX8

All three of these examples are a result of adding additional elevated lanes to avoid widening a trench section.

[hbelkins]

Would westbound I-64 just after entering Illinois from Missouri count?

[kphoger]

I'm not sure that these recent submissions fit the "obstacle" part of the challenge.  Splitting a highway into two roadways isn't really the same thing as going around an obstacle.

It's more like this and this–except if they were freeways instead of local roads.

I haven't been able to come up with an example so far.

[jmacswimmer]

Once the HRBT expansion is completed, I-64 will qualify there in the same vein as I-95 in the FMT.

When the Chesapeake Bay Bridge is running with a lane reversed on the westbound span, you have one lane of US 50 EB/US 301 NB traffic separated from the other 2.  Back when the toll plaza existed, it was always the left 2 lanes (signed for E-ZPass and no trucks) that fed the reversed lane.  (But this is moot now with the toll plaza gone and an AET gantry on the Kent Island side.)

[deathtopumpkins]

I'm not sure that these recent submissions fit the "obstacle" part of the challenge.  Splitting a highway into two roadways isn't really the same thing as going around an obstacle.

It's more like this and this–except if they were freeways instead of local roads.

I haven't been able to come up with an example so far.

Meh, if splitting to go through separate tunnel tubes counts, then splitting to go either below or above a cross street should count as well. What "obstacle" are the separate tunnel tubes going around?

[briantroutman]

Kind of on I-88 (IL)
https://goo.gl/maps/ATmfXLG6n5oHsBz7A

Yeah–I'd put that in the "kind of"  category. It has some of the trappings of a C/D lane, even though there isn't an adjacent loop to cause weave.

I-90 Eastbound, Mount Baker Tunnel, Seattle.  Advance sign.  Secondary sign.  Actual split.

Thanks; This seems to be the best example I've seen yet, and it's close to how I would have imagined such a setup to be signed.
Overhead green guide sign: "I-90 East - Spokane - ALL LANES – and also a modified W6-1-type sign as in the Fort McHenry Tunnel split.

There have to be numerous examples (non-freeway) of agencies continuing to use truss and other bridges.  Portland, Hawthorne Bridge.  Surrey, BC Nicomekl River Bridge.

At least in the case of the Surrey example, I'm surprised that–at least from what I can see on Street View–there doesn't seem to be any signage addressing the split (other than the object markers on the bridge itself). Approaching the bridge northbound at Crescent Road, I can see the split and the bridge approaches, but I can't clearly tell where the lanes ultimately lead. So I think there'd be some potential for confusion as motorists approach and possibly interpret the lane division as some sort of wye. (Edited to add: I now see that there's a sign farther south directing NB traffic bound for King George Blvd. and Nicomekl Rd. to use the left lane.)

I-95 on the Capital Beltway in VA/DC/MD. While it's signed Thru and Local, the local lanes seem to often be faster (possibly due to the large number of motorists not familiar with the area and driving slower than necessary in the thru lanes).

That observation gets at the primary point I was wondering about. Even if "Thru"  or "Express"  isn't entirely accurate–as you mentioned, the so-called "Local"  lanes might be faster–the application of those labels to the separated lanes at least implies some kind of classification to the traffic, again, even if it's contrived. A motorist can say "I'm going through–so I'll keep left" .

CA 24 when approaching the Caldecott Tunnel(s) in Oakland, CA.  Traffic is split between four separate tunnels (two eastbound, two westbound).

I've driven through the Caldecott Tunnel when I lived in the San Francisco area and completely forgot about its four bores. It appears that the split is virtually unsigned and unmentioned: The lane lines separating the lanes bound for the different bores merely go from broken to solid, and then the lanes gradually separate, with the requisite object markers and crash cushions at the gore.

There appears to be some kind of a backlit display approaching the tunnel. Do you know if that displays tunnel-related info (such as lane closures for tunnel maintenance)?

Grand Central Parkway in Flushing, NY has one W Bound where thee route splits around the two arched overpasses.  The EB side goes under one wider more modern bridge.

You're talking about this, right? I'd say that's an interesting example and a slightly different take on the similar handling of the I-90 split in Seattle mentioned above. Two identical overhead guides reassuring motorists that all lanes go to the same place.

I-10 in San Antonio
...
I-35 also splits into an upper and lower level TWICE in San Antonio
...
I-35 splits again in Austin

So for the two San Antonio examples, do VMSes give motorists driving time "via upper"  vs. "via lower"  or anything like that? Or do other signs leading up to the split give guidance like "Local Traffic use Upper Level" ? I'm trying to determine if the motorist is being given any reason to select one option vs. the other–which would, in effect, make the upper and lower levels function like the "express"  and "local"  lanes in other examples.

Of the two San Antonio examples, the I-10 is arguably the best since the motorist is presented two virtually identical guide signs:  "I-10 West - US 87 North - El Paso"  with only the "Upper"  and "Lower"  panels distinguishing between the two. And although the Culebra Ave. exit is accessed via the upper deck, the signage directs exiting traffic to the right lane specifically.

On the I-35 (San Antonio) example, though the signage doesn't strictly say "thru"  and "local" , I think the signage effectively functions that way since I-35's southbound control city appears only on the lower level guide sign; the upper level sign lists only I-10's control cities.

Likewise on the Austin example, the exit tabs and destinations provide some fairly clear guidance on which traffic is to use which lanes.

Would westbound I-64 just after entering Illinois from Missouri count?

You mean this? Yes, that more or less counts. Although it's not marked as such, the control cities tend to imply "thru"  and "local" . Like in the I-35 example from San Antonio above, I think most motorists would tend to keep left at the split unless they were heading to East Saint Louis.

I'm not sure that these recent submissions fit the "obstacle" part of the challenge....
It's more like this and this–except if they were freeways instead of local roads.

Although I put it into the title (since that was the scenario that put the idea into my head originally), I don't want to overemphasize the "obstacle"  part. A split into multiple carriageways for another reason could potentially qualify. But I think the more logical scenario is that through lanes of a freeway would have to split in order to pass between supports of an existing bridge, through separate bores of a tunnel, parallel spans of a bridge, etc. Or it could be some giant immovable obstacle that a DOT decided to build lanes around rather than remove it.

But as I've alluded to above, what I'm most interested in is how traffic control is handled when all lanes are through and there's no other logical separation to the traffic. In your Wichita examples, there is a logical separation–in both cases, a left turn lane. And in some of the instances above, signage either implies that through traffic should take one fork vs. the other. But what happens when there is no logical reason to segregate types of traffic between the two? Do you fabricate a reason–such as labeling the left lanes as "express" , even if they're no faster? For me, it's been interesting to see some of the examples, ranging from WSDOT's "I-90 - ALL LANES"  to NYSDOT's side-by-side BGSes on the GCP to the virtually silent handling of the Caldecott Tunnel by CalTrans.

Once the HRBT expansion is completed, I-64 will qualify there in the same vein as I-95 in the FMT.

And do you assume it will be signed similarly?

[FrCorySticha]

Would westbound I-64 just after entering Illinois from Missouri count?

You mean this? Yes, that more or less counts. Although it's not marked as such, the control cities tend to imply "thru"  and "local" . Like in the I-35 example from San Antonio above, I think most motorists would tend to keep left at the split unless they were heading to East Saint Louis.

I lived in the St. Louis Metro East (Illinois side of the St. Louis Metro area) and traversed the Poplar Street Bridge many times. More often than not I found myself on the left "thru" side than the right "local" side, and it seemed that traffic would follow that same pattern. This was 20 years ago, but I doubt it's changed much since.

[skluth]

Would westbound I-64 just after entering Illinois from Missouri count?

The outer lanes are technically C/D lanes for IL 3 and Tudor Avenue. I used them regularly when I lived in STL because they were frequently quicker than the through lanes.

[idk]

Kind of on I-88 (IL)
https://goo.gl/maps/ATmfXLG6n5oHsBz7A

Another kind of:
https://www.google.com/maps/@31.0875225,-104.0630782,3a,75y,232.05h,90t/data=!3m6!1e1!3m4!1sjM6Bb4aPIx-9Z0Qr9FExEw!2e0!7i16384!8i8192
I think this is to get I-20 westbound traffic on I-10 eastbound.

[ilpt4u]

Would westbound I-64 just after entering Illinois from Missouri count?

Since Eastbound I-64 exits right after the short split carriageways rejoin, I've always thought that "split"  should be signed I-64 and IL 3 in the Right Lanes, and I-55 and I-70 in the Left Lanes upon entering IL before the split, but IDOT does not sign it that way

[kphoger]

The outer lanes are technically C/D lanes for IL 3 and Tudor Avenue. I used them regularly when I lived in STL because they were frequently quicker than the through lanes.

And I used them regularly because I was usually exiting or entering at one of those two crossroads.

[Bruce]

I-5 at SR 538: the interchange was widened recently to add split lanes for thru traffic

https://www.mountvernonwa.gov/915/College-Way-Widening-Under-Interstate-5

[TheGrassGuy]

I-287 at the I-78 interchange. SB only, because going NB you can only access Exit 21A from one side and Exit 21B from the other.

[noelbotevera]

Garden State Parkway, Woodbridge, NJ - This is a...weird example. My interpretation: when the Driscoll Bridge became the Driscoll Bridges in 2006, the old SB side became the through NB side. The old NB bridge and exit 127 looks to be reconstructed, turning the old NB side into a glorified exit ramp but with a chance to return if you mess up. This split is signed, but the re-entry ramp to GSP NB isn't signed until the split.

This situation doesn't exist SB, as you don't get a chance to return to the GSP SB - you have to exit onto the Turnpike or US 9/NJ 440.

[sprjus4]

Once the HRBT expansion is completed, I-64 will qualify there in the same vein as I-95 in the FMT.

Not necessarily. The new lanes are going to be HO/T lanes, so they would already be barrier separated along the entire length from I-564 to Hampton.

The final configuration is proposed to be 2 general purpose lanes + 1 HO/T lane + 1 part-time left shoulder HO/T lane in each direction, creating a total of 8 lanes during peak hours.

[fillup420]

This one on US 70 in Durham NC really only qualifies for the obstacle part, as eastbound traffic now occupies the spot to the left of the column. However it is a very dangerous spot, and there have been multiple crashes in the past couple years. Luckily that rail bridge is due to be removed, and replaced by the bridge right behind it.

[Revive 755]

IIRC there is (was?) a plan to do this on eastbound US 40 in St. Louis around the Last Missouri Exit to get a third through lane to the PSB.  The obstacle in this case being the supports for the westbound lanes on the upper level of the double deck section.