Interesting roundabout design (Nutley Street interchange)

[tradephoric]

What do you think of this roundabout design? 


https://outside.transform66.org/about_the_project/project_sections/nutley.asp

https://www.youtube.com/watch?v=FAt0MunyYB8

[1995hoo]

That's not too far from where my mom lives, though I haven't driven through it since the roundabouts were finished and I know she said she was actively avoiding Nutley until all the construction was complete. The thing I've been wondering is whether the bypass lanes (intended for use by traffic heading from northbound Nutley to westbound I-66 or southbound Nutley to eastbound I-66) could be used by thru traffic on Nutley as a means of bypassing the first roundabout in the respective direction and thus theoretically* not having to yield to anyone. That is, in the diagram notice how the bypass lane avoids the roundabout but then rejoins the other two lanes on the overpass. Why couldn't you bypass the roundabout and then change lanes back to the left?

*"Theoretically" here is intended to denote that other drivers may not respect their obligation to yield to traffic on the roundabout.

[74/171FAN]

The thing I've been wondering is whether the bypass lanes (intended for use by traffic heading from northbound Nutley to westbound I-66 or southbound Nutley to eastbound I-66) could be used by thru traffic on Nutley as a means of bypassing the first roundabout in the respective direction and thus theoretically* not having to yield to anyone.

I think that these bypass lanes should default you right onto I-66. 

[1995hoo]

The thing I've been wondering is whether the bypass lanes (intended for use by traffic heading from northbound Nutley to westbound I-66 or southbound Nutley to eastbound I-66) could be used by thru traffic on Nutley as a means of bypassing the first roundabout in the respective direction and thus theoretically* not having to yield to anyone.

I think that these bypass lanes should default you right onto I-66. 

On the other hand, suppose someone exiting I-66 wants to turn around–presumably he'd go through the roundabout and then change lanes to the right to exit back onto I-66. If that move is allowed, then presumably it's possible to change lanes to the left from the bypass lane back to the thru lanes.

[kalvado]

That's not too far from where my mom lives, though I haven't driven through it since the roundabouts were finished and I know she said she was actively avoiding Nutley until all the construction was complete. The thing I've been wondering is whether the bypass lanes (intended for use by traffic heading from northbound Nutley to westbound I-66 or southbound Nutley to eastbound I-66) could be used by thru traffic on Nutley as a means of bypassing the first roundabout in the respective direction and thus theoretically* not having to yield to anyone. That is, in the diagram notice how the bypass lane avoids the roundabout but then rejoins the other two lanes on the overpass. Why couldn't you bypass the roundabout and then change lanes back to the left?

*"Theoretically" here is intended to denote that other drivers may not respect their obligation to yield to traffic on the roundabout.

And the purpose of that? You basically dealing with merging same traffic. Things would depend on stripping at the top and bottom of the dogbone. Green line suggests exit traffic has to take inner lane for crossing   the highway.
Overall, a great design - all disadvantages of roundabout, diamond and cloverleaf in the same package!  That's really something to be proud of

[tradephoric]

Instead of having just one bypass lane for traffic entering the freeway, why not design it so that all through traffic on the arterial bypasses the roundabout?  This design would make it so that traffic traveling on the arterial wouldn't have to yield at the roundabout.  I always wanted to see this roundabout interchange design be built...

https://www.youtube.com/watch?v=W8k1acLeK7E

[kalvado]

Instead of having just one bypass lane for traffic entering the freeway, why not design it so that all through traffic on the arterial bypasses the roundabout?  This design would make it so that traffic traveling on the arterial wouldn't have to yield at the roundabout.  I always wanted to see this roundabout interchange design be built...

https://www.youtube.com/watch?v=W8k1acLeK7E

There are no miracles in the world. There is exit traffic crossing highway and straight-through arterial traffic. They need to merge at some point.
You may designate that as a single-point yield at roundabout entrance, or as side-by-side merge on overpass, result is still similar.

[tradephoric]

The PARCLO A4 ramps eliminate the need to have full blown roundabouts.  They can suddenly be converted to "half roundabouts" and it simplifies operations/less crashes/maintains better arterial coordination.  I'm trying to see the downside of the design i'm just not seeing it. 

[1995hoo]

And the purpose of that? You basically dealing with merging same traffic. Things would depend on stripping at the top and bottom of the dogbone. Green line suggests exit traffic has to take inner lane for crossing   the highway.
Overall, a great design - all disadvantages of roundabout, diamond and cloverleaf in the same package!  That's really something to be proud of

I've never seen anyone stripping in a roundabout, but I wonder how many crashes that might cause as people stare at the stripper.

[kphoger]

I've never seen anyone stripping in a roundabout

It happens a lot during four lanning projects.

[Henry]

I tip my hat to whoever at VDOT dreamt up this highly unusual variation. Certainly a departure from the expected, with the freeway exits also including a cloverleaf.

[1995hoo]

I tip my hat to whoever at VDOT dreamt up this highly unusual variation. Certainly a departure from the expected, with the freeway exits also including a cloverleaf.

It used to be a cloverleaf with C/D roads on I-66 prior to the reconstruction as part of the HO/T lane project. The C/D roads were eliminated because there was no longer enough space for them, so I wonder if that's what motivated rebuilding the interchange (given that cloverleaf weave areas that use the right lane of traffic don't work too well on highways that are as busy as I-66 is).

[mrsman]

I'm not a fan of this.  Too much merging around with the roundabouts.

A conversion to a parclo A4 or a parclo B4 would likely be much better.

[cockroachking]

I'm not a fan of this.  Too much merging around with the roundabouts.

A conversion to a parclo A4 or a parclo B4 would likely be much better.

I disagree; from the few times I have driven through the new configuration, I think it works great. Much better than sitting around for way too long doing nothing at a traffic signal.

[tmoore952]

The drawing of the roundabout design reminds me somewhat of what my wife and I were dealing with in the UK (on the M routes) two months ago. Generally she was driving and I was looking at the GPS, and so I was the one who had to look at the roundabout design on the GPS in real time and tell my wife what lane to be in. This picture reminds me of that.

Those UK exits had full roundabouts at the top of each ramp. If there were four exits to the roundabout --- if you exited the M-way, first and third exits were for intersecting road (one way or the other), second exit was to return to the M-way, and I assume that you were prevented from taking the fourth exit which would put you on a wrong way ramp (on the ramp you just came up). I never got to observe the fourth exit, it was difficult enough with the opposite-side driving and our general uneasiness with the new situations just to make sure we took the exit we wanted. We did make some mistakes.

The new Nutley St. layout here is an adaptation of an older interchange (as described elsewhere in this thread). I also used to live near here, but in 2000-2001, so I only know the old interchange.