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National Boards => General Highway Talk => Topic started by: 1995hoo on July 08, 2013, 02:58:28 PM

Title: Simultaneous merges from both sides
Post by: 1995hoo on July 08, 2013, 02:58:28 PM
I've passed this spot twice in the past four days (picture is a video capture from Friday afternoon) and found myself wondering where else this design quirk exists. This is the I-495 Outer Loop's Express Lanes (HO/T lanes) just north of Tysons Corner, Virginia. The onramp entering from the left comes from Virginia Route 267 (the Dulles Toll Road) and the one entering from the right comes from Jones Branch Drive, a local street in a corporate park. The configuration ahead is that the left acceleration lane (marked Exit Only) becomes exit-only at Westpark Drive, the left thru lane becomes an option lane to exit or stay on the Beltway, the lane I'm in remains the right thru lane, and the right onramp merge ends.

I can't recall off the top of my head having seen this kind of thing elsewhere, though I wouldn't be surprised if some older road somewhere had something similar (say, one of New York City's older "expressways"). In this case the anticipated lower traffic volumes in the Express Lanes (due to the HOV-or-toll requirement and the limited exits) might have been a major reason why the design was approved.

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi31.photobucket.com%2Falbums%2Fc378%2F1995hoo%2FRoad%2520sign%2520pictures%2FTysonsmerge_zpsc2ed1cd7.jpg&hash=018460ae6f7c8066360e9c2197381b55cba7c05f)
Title: Re: Simultaneous merges from both sides
Post by: hobsini2 on July 08, 2013, 03:33:47 PM
The eastbound I-90/94 merge aka the Edens Junction is the only one I know of with that kind of merge.
Title: Re: Simultaneous merges from both sides
Post by: cpzilliacus on July 08, 2013, 04:09:06 PM
Inner Loop of I-495 (Capital Beltway) in Bethesda, Montgomery County, Md. just east of Pooks Hill (I-495/I-270/Md. 355 interchange Exits 34 and 35) is something similar to that.  GSV here (https://maps.google.com/maps?q=bethesda+md&ll=39.016083,-77.098145&spn=0.00932,0.01929&hnear=Bethesda,+Montgomery,+Maryland&gl=us&t=h&z=16&layer=c&cbll=39.016166,-77.098365&panoid=xXEiVTqmix5ZsjMQf6S1AA&cbp=12,114.83,,0,20.02).

Maryland SHA has made an effort to extend the left-side merge some distance ahead, but that does not really help that much. It is one of the worst and  most-congested sections of the Beltway.
Title: Re: Simultaneous merges from both sides
Post by: vdeane on July 08, 2013, 08:42:17 PM
The I-390/I-490 comes pretty close.
Title: Re: Simultaneous merges from both sides
Post by: vtk on July 09, 2013, 03:24:13 AM
I-670 WB, ramps from I-270 NB:
https://maps.google.com/?ie=UTF8&ll=40.009435,-82.909961&spn=0.002753,0.00353&t=k&z=18&vpsrc=6

I-70 EB, ramp from OH 315 SB and ramp carrying I-71 NB:
https://maps.google.com/?ie=UTF8&ll=39.951483,-83.013658&spn=0.001378,0.001765&t=k&z=19&vpsrc=6

I-70 WB, ramps from OH 315 SB and I-71 NB:
https://maps.google.com/?ie=UTF8&ll=39.950298,-83.021085&spn=0.001378,0.001765&t=k&z=19&vpsrc=6

Title: Re: Simultaneous merges from both sides
Post by: roadman65 on July 13, 2013, 01:24:32 PM
I-4 has a two sided merge in Downtown Orlando with FL 408 WB merging on the right and South Street merging from the left.
Title: Re: Simultaneous merges from both sides
Post by: jp the roadgeek on July 14, 2013, 11:11:35 AM
Found this one in Plainville, CT.  CT 72 westbound.  The merge from the left is the flyover from I-84 EB.  The merge from the right is from CT 372.

https://maps.google.com/maps?hl=en&ll=41.673809,-72.847574&spn=0.000032,0.021136&t=m&z=16&layer=c&cbll=41.673774,-72.847478&panoid=930xkNUaFs81ncfYpRs-vA&cbp=12,332.06,,0,0 (https://maps.google.com/maps?hl=en&ll=41.673809,-72.847574&spn=0.000032,0.021136&t=m&z=16&layer=c&cbll=41.673774,-72.847478&panoid=930xkNUaFs81ncfYpRs-vA&cbp=12,332.06,,0,0)

Another dangerous one that has been eliminated was just before the Bulkeley Bridge on I-84 in East Hartford when the ramp from CT 2 West would come in from the left, and the Governor Street (abandoned I-284) ramp would come in from the right.
Title: Re: Simultaneous merges from both sides
Post by: Joe The Dragon on July 14, 2013, 08:16:58 PM
https://maps.google.com/?ll=42.158286,-87.872536&spn=0.002935,0.006791&t=h&z=18

does this count? I-94 / I-294 / lake cook rd ramp
Title: Re: Simultaneous merges from both sides
Post by: 2Co5_14 on July 16, 2013, 01:05:57 PM
Interchange of I-94 & M-10 in Detroit: all directions feature left & right merge at the same point.
https://maps.google.com/maps?q=Michigan&hl=en&ll=42.359582,-83.076339&spn=0.007159,0.016512&sll=39.118141,-94.563103&sspn=0.015033,0.033023&oq=mi&t=h&hnear=Michigan&z=17 (https://maps.google.com/maps?q=Michigan&hl=en&ll=42.359582,-83.076339&spn=0.007159,0.016512&sll=39.118141,-94.563103&sspn=0.015033,0.033023&oq=mi&t=h&hnear=Michigan&z=17)