AARoads Forum

National Boards => General Highway Talk => Topic started by: hotdogPi on January 25, 2014, 09:41:40 PM

Title: Does this type of intersection have a name?
Post by: hotdogPi on January 25, 2014, 09:41:40 PM
(If you find yourself asking the same question for a different type, you can post it here.)

This is the intersection of US 3, MA 2, and the Eliot Bridge/Greenough Blvd.

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fmaps.googleapis.com%2Fmaps%2Fapi%2Fstaticmap%3Fcenter%3D42.37286%2C-71.134366%26amp%3Bzoom%3D17%26amp%3Bsize%3D300x300%26amp%3Bsensor%3Dfalse&hash=0f0426d023c2c8b966e40a2486b0f7813232fbfa)

Just for fun, to cross the Eliot Bridge, you will be going through two more of these.
Title: Re: Does this type of intersection have a name?
Post by: NE2 on January 25, 2014, 10:06:25 PM
If two of the approaches clearly form a through route, it's a seagull (http://en.wikipedia.org/wiki/Seagull_intersection). Otherwise, I guess I'd call it a channelized wye.
Title: Re: Does this type of intersection have a name?
Post by: hotdogPi on January 25, 2014, 10:16:04 PM
This has a 6-way intersection in the middle.

And the orange (US 3, MA 2) is definitely the through route.

This probably is a seagull, although only some seagulls have 6-way intersections.
Title: Re: Does this type of intersection have a name?
Post by: briantroutman on January 25, 2014, 10:42:59 PM
I've never seen the term "Seagull"  before and suspect it's largely an Aussie term. Search it on Google, and other than Wikipedia, nearly all of the first page hits are .au sites. The Wikipedia article references a FHWA document that refers to it as a Continuous Green T. But since a traffic signal has been added to the through US 3 East/MA 2 South lanes in your example, I suppose it would be a Non-Continuous T. It's essentially a directional T flattened onto one plane.

I've encountered a similar intersection (http://bit.ly/1aWAuik) near Lexington, MA. This arrangement is complicated slightly, though, in that a through movement was added to the north-to east channelized path–and given preference over the otherwise continuous east-west roadway. And it also doesn't bring the two intersecting channels to a single point with the inner through lanes as your example does.

The single, signalized crossing point probably works best with heavy traffic volume and specifically with heavy turning volume whereas the non-signalized, off-mainline crossing works better where overall volume is lower and a greater proportion of traffic is following the through movement on the continuous road.

MassDOT seems to like these.
Title: Re: Does this type of intersection have a name?
Post by: Alps on January 26, 2014, 12:53:47 AM
I call them all wyes.
Title: Re: Does this type of intersection have a name?
Post by: Road Hog on January 26, 2014, 01:20:57 AM
Is the middle crossing grade-separated or is it a single grade with lights?
Title: Re: Does this type of intersection have a name?
Post by: froggie on January 26, 2014, 08:06:30 AM
Since the OP mentioned intersection, it's likely at-grade with a traffic signal.  There's one in Tappahannock, VA at the southern junction of US 17/US 360.  I'm with Steve....it's basically just a 3-way wye.
Title: Re: Does this type of intersection have a name?
Post by: colinstu on January 27, 2014, 12:20:34 AM
Looks like an at-grade version of a "Directional T interchange" / "Full Y interchange" to me.

In other words, ridiculous.

The example could very easily be converted into a roundabout.

Looking around the map there are two other intersections just like the one in the screenshot.
Title: Re: Does this type of intersection have a name?
Post by: NE2 on January 27, 2014, 12:28:06 AM
Quote from: colinstu on January 27, 2014, 12:20:34 AM
The example could very easily be converted into a roundabout.

Looking around the map there are two other intersections just like the one in the screenshot.
All three intersections used to be rotaries, but were converted between 1955 and 1969.
Title: Re: Does this type of intersection have a name?
Post by: cpzilliacus on January 27, 2014, 01:00:45 AM
Quote from: froggie on January 26, 2014, 08:06:30 AM
Since the OP mentioned intersection, it's likely at-grade with a traffic signal.  There's one in Tappahannock, VA at the southern junction of US 17/US 360.  I'm with Steve....it's basically just a 3-way wye.

There's something similar at the junction of U.S. 1 Alternate (Baltimore Avenue and Bladensburg Road) and Md. 450 (Annapolis Road) (https://maps.google.com/maps?q=bladensburg+md&ll=38.939576,-76.941215&spn=0.004081,0.007929&oe=utf-8&client=firefox-a&channel=np&hnear=Bladensburg,+Prince+George%27s,+Maryland&gl=us&t=m&z=17) in Bladensburg, Prince George's County, called the "Peace Cross" (because of the large cross nearby) by old-timers.
Title: Re: Does this type of intersection have a name?
Post by: froggie on January 27, 2014, 05:36:41 AM
QuoteThe example could very easily be converted into a roundabout.

The one in Ottumwa, IA at US 34/US 63 South has...
Title: Re: Does this type of intersection have a name?
Post by: PurdueBill on January 27, 2014, 08:56:47 PM
Growing up near Boston, I always called the crazy intersections like those as well as the former one on the Lynnway (not quite as complex, but still more complex than it needed to be) good old MDC Specials!  It seemed like the MDC roads liked to have overdone intersections with at-grade "ramps", 6-way intersections, and so on.
Title: Re: Does this type of intersection have a name?
Post by: lepidopteran on January 28, 2014, 07:03:04 PM
There used to be one like this in Robbinsville, NJ at the T-intersection of US-130 and NJ-33 (http://www.historicaerials.com/aerials.php?scale=5.53132801877025E-06&lat=40.2161078229273&lon=-74.6207138560899&year=2002).  One movement appears to be missing, though.  A new road was eventually built in the fourth direction, and it was converted into a conventional 4-way intersection in the early 2000's.
Title: Re: Does this type of intersection have a name?
Post by: Alps on January 28, 2014, 11:49:49 PM
Quote from: PurdueBill on January 27, 2014, 08:56:47 PM
Growing up near Boston, I always called the crazy intersections like those as well as the former one on the Lynnway (not quite as complex, but still more complex than it needed to be) good old MDC Specials!  It seemed like the MDC roads liked to have overdone intersections with at-grade "ramps", 6-way intersections, and so on.
The MDC sure loved their traffic islands. Islands everywhere, channelizing everyone. More things to crash into!
Title: Re: Does this type of intersection have a name?
Post by: PurdueBill on January 29, 2014, 12:36:22 AM
Quote from: Alps on January 28, 2014, 11:49:49 PM
Quote from: PurdueBill on January 27, 2014, 08:56:47 PM
Growing up near Boston, I always called the crazy intersections like those as well as the former one on the Lynnway (not quite as complex, but still more complex than it needed to be) good old MDC Specials!  It seemed like the MDC roads liked to have overdone intersections with at-grade "ramps", 6-way intersections, and so on.
The MDC sure loved their traffic islands. Islands everywhere, channelizing everyone. More things to crash into!

Islands not even wide enough to safely harbor more than one pedestrian in a median or a bike!  (I remember diamond warning signs reading "Pedestrian Islands" and wondering what good they were.)  Gores and merges! 

Thank goodness (or too bad, depending on your viewpoint) there are still plenty of good old MDC masterpieces out there.  Some of them may never go away.  Even better was where MDC and DPW work would meet and you could pick out where one agency's work started and the other stopped based very easily.  (Normal-sized BGSs with standard fonts? Must be on DPW turf now!)