National Boards > General Highway Talk

"Duplicate" Ramps

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webny99:
What are some examples where two different freeway entrance ramps could be used for the exact same movement? This could be freeway to freeway or surface street to freeway (but not express or HOV lane entrances paired with a regular entrance). If possible, also include some context as to why the setup exists.

Here are the first three that came to mind, inspiring this thread:

(1) NY 33 at I-490
Cloverleaf interchange with a slight modification means there are two ramps that serve the NY 33 WB to NY 531 WB movement. The ramp that's part of the cloverleaf goes to NY 531, while the sole left turn in the interchange complex serves the NY 33 WB to I-490 EB movement... but in doing so also provides access to I-490's ramp to NY 531.

(2) NY 5 at I-90/I-290
Also a modified cloverleaf, the most noticeable modifications are the loop in the southwest corner being folded over the freeway, and the northwest quadrant having straight-through movements for traffic to/from Kensington Ave. Look a bit closer at the southwest quadrant, and you'll also notice that the on-ramp from NY 5 EB joins I-290 after the split for I-90 traffic, meaning it's actually a direct ramp to I-90 WB. But because of the Kensington Ave modification, there's still an option for NY 5 EB traffic looking to get to I-90 EB. They must turn left and join the loop ramp to access I-290, then merge left to reach I-90 EB at the upcoming split... or use the loop as an alternative to I-90 WB.

(3) US 275 at I-80
On US 275 EB, the loop ramp is signed for I-680 North, while getting to I-80 East requires a left turn (or so you'd think). But both ramps end up on the same roadway, with a split for I-680 and I-80 traffic about 1/2 mile down the road. This was presumably done to reduce merging on that stretch, which makes sense but also creates an extra light for the left turn on US 275.

Bruce:
The Broadway Interchange in Everett, WA has a few examples: EB SR 526 to NB I-5 can be done via a left-lane ramp with access just beyond Evergreen Way (which then crosses under SR 526 and flies over) or via a loop ramp on the east side. NB SR 99 to NB I-5 has a dedicated ramp or one could turn right onto SB SR 527 and take the aforementioned loop ramp. For both of these, the flyover ramps were added in later upgrades to the interchange; SR 526's was added in the 1990s to handle demand from Boeing's 777 program, while SR 99's was there once a few bridges were moved around in the 1960s or 1970s.

Down in Seattle, I-5 at Northgate Way has two ways for traffic on 1st Avenue Northeast to enter I-5 NB: either the southern onramp from the mall or the ramp from the five-way intersection at Northgate Way itself.

Big John:
I-75 SB to I-285 EB, NW Altanta. There is a newer multi-lane flyover ramp and an older loop ramp that both access it.  The reason the older loop ramp still exists is that traffic entering I-75 from Windy Hill Rd doesn't have access to the newer flyover ramp.

dlsterner:
I can't help but think that we've had this thread before ...  But I'll contribute instead of being pedantic :)

Here are two cases near me:

1) Near Ellicott City MD - northbound US 29 to westbound I-70.  There is a loop ramp in the NE quadrant, although you can also turn left off US 29 and get onto the ramp that serves southbound US 29.  Personally, I prefer the latter since it's easier to get up to speed for merging onto I-70.

2) South of Baltimore - northbound I-97 to westbound I-695.  You normally would take an exit to the right onto a flyover, making a left hand merge onto I-695.  Later a second loop ramp was added after crossing I-695.  This was helpful for traffic that wanted to immediately exit onto MD 648 northbound, which was not possible from the flyover.

GaryV:
For several years, at the end of EB Bus I-196 (Holland/Zeeland area), there were duplicate ramps to EB I-196. There was the signed cloverleaf ramp which was the intended ramp. But the ramp from the opposite direction could also be used. Since WB Byron Rd didn't have much traffic, you could often save a little time by making the left turn.

Later a "NO LEFT TURN" sign was put up, and the current configuration has a median island that doesn't allow the turn.

https://www.google.com/maps/@42.8117226,-85.9803764,311m/data=!3m1!1e3?authuser=0&entry=ttu

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