Strange interchange in my hometown...
Chris H.
I live in a four-city area in northwest Alabama commonly referred to as "the
Shoals". Florence, the largest city of about 40k people, is separated by the
Tennessee River from the other three cities on the south side.
Currently, work is progressing on a new six-lane bridge linking the cities,
a bridge that was originally proposed in the mid-70s. US 43 and US 72 run
through the cities; when the bridge and adjacent corridor is complete, 43
will use the new bridge while 72 will use the existing four-lane span to the
west.
This new corridor really annoys me. Overpasses are being built for the new
road over major intersections. However, two of these interchanges are really
frustrating to me. There is only one "ramp", and at both of these
intersections it will be a four-lane, two way road. They are located on the
southeast sides. It looks something like this:
| |
| New |
| Road |
| |
-------------- | | -----------------------------------------
Existing | Overpass | Traffic
Road | | Light
-------------- |
|----------------- ---------------
| | |
|
| | |
|
| | /
|
| |_ _ _ _ _ _ _ / |
| Traffic -----> /
| Light <----- /
| _ _ _ _ _ _ _ _ _ _ _ _ /
| |
| |
I haven't attempted many diagrams, so forgive me if that's not the greatest
you've ever seen. The thing that bothers me the most here is the traffic
light on the new road. This is almost negating the entire purpose of
building the overpass, is it not? Sure, some cross-traffic is eliminated,
but the flow of traffic on the new road will still be interrupted at times.
Why not just build, at the least, a diamond interchange? Admittedly, the
terrain could be a problem at one of these intersections, but certainly not
the second one.
So, are these types of interchanges common? This is the first time I can
remember seeing one like this.
Sorry for the long, rambling post. Just trying to vent some frustration I
have for ALDOT, hehe.
Have a good day everybody...
Chris H.
Florence, AL
Steve
I went over one of these on US 1, connecting to RI 102 (? - either that
or 103 or the road where 103 is being built). If one end can't be
diamonded or trumpeted either due to terrain, space, or traffic
limitations, then I understand this. The configuration as it stands now
allows three signal phases instead of four, reducing backups and wait
times, plus eliminating cross traffic across both major highways (which
reduces the potential for accidents as well as the signal time for the
intersecting road).
Joe Galea
"Steve" <smal...@hackmit.edu> wrote in message
news:3CB0C9DB...@hackmit.edu...
The advanatage of this would be having much longer green lengths for the
through roads, with short phases for the little ramp.
Joe Galea
Chris Aseltine
[five pages of poorly wrapped, quoted text, followed by a one-sentence
response]
> The advanatage of this would be having much longer green lengths for the
> through roads, with short phases for the little ramp.
Please. Please, learn to trim.
Scott O. Kuznicki
of it as a grade-separated single-ramp double-jughandle :)
US 20 and IL 75 north of Freeport, IL (no signal on US 20)
http://terraserver.homeadvisor.msn.com/image.asp?S=11&T=1&X=720&Y=11719&Z=16
&W=2
US 14 and US 218 - east of Owatonna, MN (soon to be converted, no signals)
http://terraserver.homeadvisor.msn.com/image.asp?S=10&T=1&X=2424&Y=24392&Z=1
5&W=2
IL 50 at Ogden Av in Cicero, IL (new, will never ever be a freeway, but
shoulda been)
Seems to me there's one of these somewhere in Wisconsin, perhaps not
signalized?
As long as they own land on other quadrants (at least two total, on opposite
corners), it can ultimately accomodate an interchange that will allow
uninterupted flow on one facility.
Its main advantage is that it does significantly reduce delay on BOTH
roadways. Think about it - if the volume split was 50/50, with 10% of
approach volumes turning on each approach, you've just reduced the required
red time on the each street by 40% (assuming both movements operate
independently, with no overlaps), since all you have to accomodate was that
street's turning vehicles. In the case of Cicero/Ogden, there's an
*eight*-lane connector road (plenty of storage - 2 lefts, 2 rights each
direction) to further improve progression and signal timing on the main
roads by improving the capacity of the connector to obtain maximum cycle
lengths. Also, conflict points are reduced and the crash severity will
likely go down significantly.
Like I said, as long as they own the necessary land . . . it seems that
mistake is made far too often.
Scott Kuznicki
Dedicated Highway Enthusiast and Civil (Traffic) Engineer
To reply, please remove the word "NOSPAM" from the
e-mail address and replace with "com"
SPUI
> or 103 or the road where 103 is being built). If one end can't be
> diamonded or trumpeted either due to terrain, space, or traffic
> limitations, then I understand this. The configuration as it stands now
> allows three signal phases instead of four, reducing backups and wait
> times, plus eliminating cross traffic across both major highways (which
> reduces the potential for accidents as well as the signal time for the
> intersecting road).
This is at RI 403. I believe it is actually supposed to function as a 4 ramp
parclo, but inadequate signage greatly clouds the issue. On the west side of
the interchange, there is a sign pointing Wickford (which US 1 south goes
to) north along old US 1 (now a frontage road). Traffic for US 1 north would
continue under US 1 and to the direct connector.
US 27 northwest of Cinci has several of these double-T interchanges in a
row.
Steve
He also only paraphrased what I had just said.
Stanley Cline
wrote:
>This new corridor really annoys me. Overpasses are being built for the new
>road over major intersections. However, two of these interchanges are really
>frustrating to me. There is only one "ramp", and at both of these
>intersections it will be a four-lane, two way road. They are located on the
<snip>
IIRC, there's something like this in the Austell, GA (suburb of
Atlanta) area, and plenty in more rural areas of northern AL and
Tennessee (don't remember the examples off hand.) They probably work
OK if the traffic expected between the two roads is fairly light.
-SC
--
Stanley Cline -- sc1 at roamer1 dot org -- http://www.roamer1.org/
...
"Never put off until tomorrow what you can do today. There might
be a law against it by that time." -/usr/games/fortune
N. W. Perry
"Chris H." <chri...@hiwaay.net> wrote:
> So, are these types of interchanges common? This is the first time I can
> remember seeing one like this.
That's exactly the interchange of Brighton-Henrietta Town Line Road and
NY 15A near Rochester:
http://terraserver.homeadvisor.msn.com/image.asp?S=10&T=1&X=1437&Y=23873&
Z=18&W=1
There are numerous other interchanges in the state where more than one
of these two-way ramps is used to simulate a real interchange. See for
some examples, as well as another single-ramp version (NY 97 and NY 17B).
Jon Enslin
> This is an accepted practice on pre-freeway buildouts in the Midwest - think
> of it as a grade-separated single-ramp double-jughandle :)
>
> US 20 and IL 75 north of Freeport, IL (no signal on US 20)
> http://terraserver.homeadvisor.msn.com/image.asp?S=11&T=1&X=720&Y=11719&Z=16
> &W=2
> US 14 and US 218 - east of Owatonna, MN (soon to be converted, no signals)
> http://terraserver.homeadvisor.msn.com/image.asp?S=10&T=1&X=2424&Y=24392&Z=1
> 5&W=2
> IL 50 at Ogden Av in Cicero, IL (new, will never ever be a freeway, but
> shoulda been)
>
> Seems to me there's one of these somewhere in Wisconsin, perhaps not
> signalized?
There is a signalized one on the Lake Parkway in Milwaukee at Oklahoma Avenue.
Jon
Marc Fannin
> I live in a four-city area in northwest Alabama commonly referred to as "the
> Shoals". Florence, the largest city of about 40k people, is separated by the
> Tennessee River from the other three cities on the south side.
One of my grandfathers came from Phil Campbell and married someone
from near Lawrenceburg, TN, so I'm familiar with it. :)
[snip US 43/72 corridor info and interchange ASCII]
As you've probably read by now, there are many of this type of
interchange scattered around; I can add US 31 at old US 24 near Peru,
Indiana (until just recently it was the southern US 24/31 intersection
as US 24 used to come in from the west and follow US 31 to the north).
http://terraserver.homeadvisor.msn.com/image.asp?S=11&T=1&X=1434&Y=11278&Z=16&W=2
I want to comment that this raises a philosophical question: Is this
type of set-up an interchange or not? The mainline highways are
grade-separated from each other, yet all the connections (all two) are
at-grade and involve left turns.
________________________________________________________________________
Marc Fannin|musx...@kent.edu or @hotmail.com| http://www.roadfan.com/
Andrew Muck
There is one like that at NY 19/US 20 and one with 3 ramps at NY 78/324.
Andrew Muck
N. W. Perry
true...@yahoo.com (Andrew Muck) wrote:
> > There are numerous other interchanges in the state where more than one
> > of these two-way ramps is used to simulate a real interchange. See for
> > some examples, as well as another single-ramp version (NY 97 and NY 17B).
>
> There is one like that at NY 19/US 20 and one with 3 ramps at NY 78/324.
>
> Andrew Muck
You mean this one:
http://www.empirestateroads.com/week/week30.html
That's the link I meant to include above after the word "see". :-)
N. W. Perry
musx...@kent.edu (Marc Fannin) wrote:
> I want to comment that this raises a philosophical question: Is this
> type of set-up an interchange or not? The mainline highways are
> grade-separated from each other, yet all the connections (all two) are
> at-grade and involve left turns.
NYSDOT shows them as interchanges on its maps, for what that's worth.
SPUI
"Marc Fannin" <musx...@kent.edu> wrote in message
news:cc3aa42a.02040...@posting.google.com...
>
> I want to comment that this raises a philosophical question: Is this
> type of set-up an interchange or not? The mainline highways are
> grade-separated from each other, yet all the connections (all two) are
> at-grade and involve left turns.
The way I see it, an interchange is a configuration that reduces the number
of conflicting turns via a bridge. So this setup would be an interchange,
but a similar setup:
|
|--\
| |
----------/
|
|
would not be an interchange because you still have a standard T
intersection.
David J. Greenberger
> This new corridor really annoys me. Overpasses are being built for the new
> road over major intersections. However, two of these interchanges are really
> frustrating to me. There is only one "ramp", and at both of these
> intersections it will be a four-lane, two way road. They are located on the
> southeast sides. It looks something like this:
This is the configuration of the interchange of Plantations Road and
Judd Falls Road in Ithaca, NY, on the Cornell campus. The connecting
ramp has stop signs at either end, and it's only two narrow lanes.
However, this is an interchange only because the terrain dictates an
interchange rather than an intersection -- given the traffic volumes,
and intersection would be just fine.
This is the site of the infamous Plantations Road pipe, BTW:
http://plover.net/~green/?plantations-pipe
http://plover.net/~green/?cornell-plant-pipe_2
--
David J. Greenberger
New York, NY
David J. Greenberger
> The way I see it, an interchange is a configuration that reduces the number
> of conflicting turns via a bridge. So this setup would be an interchange,
> but a similar setup:
>
> |
> |--\
> | |
> ----------/
> |
> |
>
> would not be an interchange because you still have a standard T
> intersection.
So you wouldn't consider a typical one-sided interchange, like exit 9 on
NYC's West Side Highway/Henry Hudson Parkway, to be an interchange? It
reduces the number of conflicting turns by disallowing access to one
side of the highway, but there are no bridges.
Or what about a (hypothetical) one-way freeway?
SPUI
"David J. Greenberger" <dav...@email.com> wrote in message
news:pu15an...@email.com...
> "SPUI" <sp...@mit.BUTIDONTLIKESPeduAM> writes:
>
> > The way I see it, an interchange is a configuration that reduces the
number
> > of conflicting turns via a bridge. So this setup would be an
interchange,
> > but a similar setup:
> >
> > |
> > |--\
> > | |
> > ----------/
> > |
> > |
> >
> > would not be an interchange because you still have a standard T
> > intersection.
>
> So you wouldn't consider a typical one-sided interchange, like exit 9 on
> NYC's West Side Highway/Henry Hudson Parkway, to be an interchange? It
> reduces the number of conflicting turns by disallowing access to one
> side of the highway, but there are no bridges.
I would define an interchange as a configuration that has less traffic
conflicts than an at-grade intersection that allows the same movements.
Since a one-sided interchange is at-grade already, it does not fit that
definition. However it would be an exit worthy of an exit number, and would
not prevent a road from being a freeway.
BTW I figured out what the mystery bridging you were asking about is - it
was a temporary connection to 72nd St to/from the south before the HHP
opened. Give me a couple weeks and I'll have more info/photos/etc.
--
Dan Moraseski - 14th grade at MIT
http://spui.cjb.net/ - FL NJ MA route logs and exit lists
"Boston really isn't high on the importance scale for numbered routes
because we don't see the need to waste taxpayer money on it. Thru traffic
uses highways, not numbered surface routes. This isn't the 1950s." - some
MassHighway MassHole to Shawn De Cesari
Michael Moroney
>This is the configuration of the interchange of Plantations Road and
>Judd Falls Road in Ithaca, NY, on the Cornell campus. The connecting
>ramp has stop signs at either end, and it's only two narrow lanes.
>However, this is an interchange only because the terrain dictates an
>interchange rather than an intersection -- given the traffic volumes,
>and intersection would be just fine.
Also the intersection of NY 2 and NY 22 in Berlin NY. It has two such
ramps, but because of terrain, not traffic volume.
-Mike
David J. Greenberger
> BTW I figured out what the mystery bridging you were asking about is - it
> was a temporary connection to 72nd St to/from the south before the HHP
> opened. Give me a couple weeks and I'll have more info/photos/etc.
No, the mystery bridging looks like it's less than ten years old.
The SB entrance ramp closed as recently as the 80's. IINM, the mainline
SB highway swung to the west and the ramp came up in the median. Much
of this is still visible:
http://plover.net/~green/?wsh-72-old_1
http://plover.net/~green/?wsh-72-old_2
http://plover.net/~green/?wsh-72-old_3
http://plover.net/~green/?wsh-72-old_4
http://plover.net/~green/?wsh-72-old_5
http://plover.net/~green/?wsh-72-old_6
http://plover.net/~green/?wsh-under_b
What I was asking about was this:
http://plover.net/~green/?wsh-72-pk_2
http://plover.net/~green/?wsh-72-pk_3
But I'd be interested in seeing what you find in any case.
SPUI
> "SPUI" <sp...@mit.BUTIDONTLIKESPeduAM> writes:
>
> > BTW I figured out what the mystery bridging you were asking about is -
it
> > was a temporary connection to 72nd St to/from the south before the HHP
> > opened. Give me a couple weeks and I'll have more info/photos/etc.
>
> No, the mystery bridging looks like it's less than ten years old.
>
> http://plover.net/~green/?wsh-72-pk_3
>
> But I'd be interested in seeing what you find in any case.
http://web.mit.edu/spui/www/temp/19340603transforming_the_west_side.pdf -
this has an old aerial from before the HHP, and the location looks right. Is
it possible that this section was neccesary for structural atability, and
thus it was rebuilt along with the rest?
David J. Greenberger
> Have a look at
> http://web.mit.edu/spui/www/temp/19340603transforming_the_west_side.pdf -
> this has an old aerial from before the HHP, and the location looks right. Is
> it possible that this section was neccesary for structural atability, and
> thus it was rebuilt along with the rest?
Interesting. Yes, the location is exactly right. Your guess seems
reasonable.
I'll note that in the map shown at the bottom, the Esplanade and the
"Express Highway" are swapped -- in reality, the Esplanade runs over the
tracks and the parkway runs along the river. (I wonder why it wasn't
done the way the map indicates -- it would seem to make more sense.)
Would you happen to have any information on what this article treats as
the south end of the Henry Hudson Parkway, near Dyckman Street? In
particular, there seem to be remnants of a shared NB exit/SB entrance
structure in the parkway median. Now, the exit is a right exit and the
entrance is a modernized left entrance, not the original one.
Thanks.
SPUI
>
> Would you happen to have any information on what this article treats as
> the south end of the Henry Hudson Parkway, near Dyckman Street? In
> particular, there seem to be remnants of a shared NB exit/SB entrance
> structure in the parkway median. Now, the exit is a right exit and the
> entrance is a modernized left entrance, not the original one.
I may take a look at that, but my paper is about the WSH south of 72nd. Is
this structure at Riverside or Dyckman?
David J. Greenberger
Yes.
Oh, sorry.
It's at what is technically Riverside Drive, at the north end of the
Riverside Drive - HHP overlap. Of the four ramps, only the SB exit is
at Dyckman proper. (Was the NB entrance always at Riverside?)