Two turns for the same movement?

[jeffandnicole]

And then there's this entering the Atlantic City Expressway at exit 12: https://www.google.com/maps/@39.4457019,-74.6181563,18z
Why does the entrance split and have two merges unlike say exit 7 where the two lane entrance from the GSP merges at the same time and has the two extra lanes end some distance afterwards.

I like the theory in the design...either lane enters the highway, and the left lane doesn't have to worry about those in the right lane, while trying to merge left.  The left lane enters first, and gives traffic time to merge over before the other lane enters. 

In practice though, the first accel lane is too short, and people sometimes are a bit confused as to what lane to take as they approach the mainline highway.

There's another example sorta like that for traffic on NJ 168 South to enter Rt. 42 South:  http://goo.gl/maps/7NgMu

Almost no one uses that first ramp.  It's not even signed. http://goo.gl/maps/2HufI

[Laura]

US 17 SB leaving US 15-29 in Opal VA.  You can still turn left at the light or use the flyover further down. 

Mapmikey

Ooh, is this open now? Strange that they would still allow the left at that light.


iPhone

[kendancy66]

I-66 EB to I-495 north has two ramps. I believe that they were reconfigured when the HOT/HOV lanes were added to 495 so that one is HOT/HOV access only now. Prior to that, general traffic could use either one.

Eta: 1995hoo beat me to it by five minutes, lol

iPhone

You are actually referencing different ramps.  1995hoo was talking about exit from beltway.  You are talking about exit from I-66

So that interchange at one time had 2 ramp duplications

I am very familiar with that exit.  It was part of my commute for 10 years




iPhone

[TheStranger]

One could easily argue that the Fremont Street and Harrison Street ramps from I-80 west in San Francisco both serve the same exact movement, to Fremont Street northbound:

http://goo.gl/maps/kpzFQ

From US 101 south heading onto the Southern Freeway portion of 280, you get two ramps for Alemany Boulevard in the span of 3/4 mile (the first one seems to be an analogue to the northbound Alemany/Bayshore exit, while the second one is the only one accessible by drivers who were on 280 south before reaching 101):

https://maps.google.com/maps?q=Alemany+%26+Crescent,+San+Francisco,+CA&hl=en&ll=37.73658,-122.409582&spn=0.011353,0.01869&sll=37.734043,-122.413273&sspn=0.005676,0.009345&t=h&gl=us&hnear=Crescent+Ave+%26+Alemany+Blvd,+San+Francisco,+California&z=16

[getemngo]

The I-96/M-37/Alpine Ave interchange (exit 30), which conveniently gets to mix with the I-96/US 131/hidden I-296 interchange. Traffic heading south on M-37 can access eastbound I-96 either by making a left turn between the westbound and eastbound lanes, or by taking the loop ramp on the right. The former is signed as I-96 East; the latter is signed as "To US-131 South".

Originally none of the ramps on the eastern half of the interchange existed, except for the westbound I-96 to northbound M-37 ramp, and the interchange functioned like a weird folded diamond. The other ramps were put in sometime in the mid-'90s to reduce weaving (one of my earliest road memories), and it worked wonders. All movements are possible, and there's no weaving whatsoever except in the rarely used movement from northbound US 131 to southbound Alpine.

[Duke87]

If you want to go from Cross Bay Blvd to the Belt Parkway eastbound, you can either take the direct ramp, or proceed to the next ramp onto the Nassau Expressway, and then exit onto the Belt.
The opposite also works: if you want to go to the Nassau Expressway eastbound, you can either do it directly or get on the Belt and then exit.
https://goo.gl/maps/TUkkg


Another interesting note from the same area: the ramp from the Nassau Expressway eastbound onto the Belt eastbound is two lanes, but they split and then merge into the Belt at different points. If there is traffic on the Belt, you of course want to be in the right lane.
https://goo.gl/maps/Ruk35

[kurumi]

Manchester, CT, I-84 WB: Exit 62&60 and Exit 59 both take you to I-384. It's a little trivial because it's a C/D situation, but a little more interesting than "ooh, I can get back onto I-84". The separate exit 59 offramp is technically not needed, but then you'd have signage for "Exit 62&60&59" instead of just "Exit 62&60".

[mrsman]

http://goo.gl/maps/N86Tb

In Universal City, CA (near Universal Studios) there are two ways of reaching US 101 South from Lankershim Blvd.  Either make a right on Ventura and then a right on the on-ramp there.  Or make a left at Cahuenga Blvd W and then another left to the on-ramp.

http://goo.gl/maps/64O94

This one may not meet the requirements of the thread, but effectively allows two different ways of reaching the same movement.  I-405 SOUTH to Century Blvd or Century Blvd to I-405 SOUTH.

First, an explanation.  This interchange is close to LAX and before the construction of I-105 was the main way of reaching LAX for most of Los Angeles.  It is functionally a cloverleaf, except that the ramps to/from I-405 SOUTH hit La Cienega Blvd instead of reaching Century Blvd directly.  La Cienega in this part of town functions as a two-way service road to the freeway but it is a major street in its own right.  So coming southbound on the freeway it is signed like a cloverleaf with C/D roads.  First exit: Century Blvd West (exit, left at La Cienega, right on Century).  Second exit: Century Blvd East (exit, right on La Cienega, right on Century.  However, there are no turn restrictions at the corner of La Cienega and Century, so you could take the Century Blvd West exit make a left at La Cienega and a left at Century to go to Century Blvd East.  Similarly you can take the Century Blvd East exit make a right at La Cienega and a left at Century to go to Century Blvd West.

For Airport traffic a lot of redundancy was built in.

[jp the roadgeek]

The famous double exit on the northbound Hutch/Merritt Parkway.  There's Exit 30 in NY for King St, the King St. overpass with the state line running down the middle, then the Exit 27 loop ramp from the Merritt in CT.

[hm insulators]

Another L.A.-area one: In La Crescenta, there are two ways you can access I-210 eastbound from Lowell Avenue: You can go all the way to where the street dead-ends at the elbow onto the freeway, or you can turn left onto Honolulu Avenue, pass under the freeway and access the eastbound 210 via a loop ramp that merges with the one off Lowell. Always wondered why they did it that way, especially because those aren't heavily-used onramps.

In far-north Phoenix, if you're heading north on I-17 and want to go west on Arizona 74, you can either turn left at the traffic signal at the top of the first offramp, or you can use the loop ramp instead. I prefer using the loop ramp as it eliminates the signal.

[1995hoo]

I see this one I remember from the early 1990s still exists. In Charlottesville, the "preferred" route from westbound Preston Avenue to either westbound Grady Avenue or southbound 10th Street (in either case, generally speaking heading from downtown towards the University) is to turn left via dual left-turn lanes from Preston onto Grady (and then, if necessary, go left again onto 10th).

Thing is, the left-turn lights on Preston have never been permissive. The straight-thru light tends not to turn red all that often unless someone triggers the red cycle going to or from the Martin's Hardware car park located on what would be the fourth "leg" of that intersection. So many of us found it's often faster to go straight through on Preston, then hang a left at the next intersection (10th Street–it had a flashing yellow light when I was in school, but I believe now it has no light at all), and then make a right onto Grady Avenue (often benefitting from the ability to go right on red, as there is a right-only lane on 10th approaching Grady). There's even a left-turn lane on Preston to facilitate this movement.

Here's a Street View. The "preferred" route goes left at this light. The other (often faster) route goes straight here and takes the next left where those cars are lined up at the brick building with the white trim.

https://www.google.com/maps/@38.03865,-78.490586,3a,75y,314.87h,87.82t/data=!3m4!1e1!3m2!1selVOQcczWOkw6V7LD7LyiQ!2e0

[Ned Weasel]

Oh, here's an interchange with turn movement redundancy: I-35, US 169, K-7, and 151st Street in Olathe, Kansas!

https://maps.google.com/maps?ll=38.854832,-94.816153&spn=0.009525,0.021136&t=k&z=16

All of the movements would still be facilitated if you removed the two left turns from K-7 and removed the two left turns from 151st Street to K-7.

[jakeroot]

Oh, here's an interchange with turn movement redundancy: I-35, US 169, K-7, and 151st Street in Olathe, Kansas!

https://maps.google.com/maps?ll=38.854832,-94.816153&spn=0.009525,0.021136&t=k&z=16

All of the movements would still be facilitated if you removed the two left turns from K-7 and removed the two left turns from 151st Street to K-7.

I remember seeing this ramp a couple of times just looking around KC. If indeed some of the movements were restricted, it would probably flow better. Reducing signal phases always helps.

[cu2010]

NY342 westbound at I-81 south has two ramps in a parclo setup. Traffic from the east is supposed to use the loop ramp...but nothing's stopping you from making a left turn onto the shorter, more direct route intended for traffic from the west. Most everyone does it anyways.

Of course, this setup dates back from when 342 formed part of the primary route between Watertown and Ft. Drum (and points north)...it's since been replaced with I-781. As a result, that exit is used primarily by local traffic only  these days.