Greetings all,
I am working on a list/map of unconventional interchanges and intersections in Maryland for MDOT SHA. Unconventional interchanges include SPUI, diverging diamond, double roundabout, etc. I've put a map together of the 40 that I am aware of (https://maryland.maps.arcgis.com/home/item.html?id=6b2a39fbae2f43fe9554ec6433a398c7). Can anyone here think of any that I missed? Here's the list. Map link above.
Grade-separated & Signalized
Single Point Urban Interchange
1. I-695 & MD 140, Pikesville
2. MD 100 & MD 170, Severn
3. US 29 & Cherry Hill Rd., Silver Spring
4. MD 337 & MD 5, Camp Springs
5. MD 200 & MD 650, Colesville
Single Loop Interchange
1. MD 140 & MD 940, Owings Mills
Tight Diamond Interchange
1. MD 32 & MD 108, Columbia
2. MD 100 & Coca Cola Dr., Hanover
Diverging Diamond Interchange
1. MD 295 & Arundel Mills Blvd, Hanover
Grade-separated & Unsignalized
Double Roundabout Interchange
1. MD 100 & MD 103, Elkridge
2. US 29 & MD 216, Scaggsville
At-grade & Signalized
Jughandle Intersection
1. Hanover St. / Cromwell St., Baltimore
Superstreet Intersection
1. MD 3 & Waugh Chapel Rd., Odenton
Continuous Flow Intersection
1. MD 210 & MD 228, Accokeek
2. US 1 & MD 200(to be opened in 2014)
Continuous Green-T Intersection
1. US 40 & Enchanted Forest, Ellicott City
2. US 29 & Rivers Edge Rd., Columbia
3. MD 139 & Chestnut Ave., Towson
4. MD 100 & US 1, Elkridge
At-grade & Unsignalized
Maryland J-turn Intersection
1. US 15 & Hayward Rd., Frederick
2. US 15 & Willow Rd., Frederick
3. US 15 & Biggs Ford Rd., Frederick
4. US 15 & Sundays Ln., Frederick
5. US 15 & College Ln., Emmitsburg
6. US 15 & Old Frederick Rd., Emmitsburg
7. US 301 & Main St. Queenstown
8. US 301 & Del Rhodes Ave., Queenstown
9. US 301 & Ruthsburg Rd., Centreville
10. US 301 & Sudlersville Rd., Sudlersville
11. US 301 & McGinnes Rd., Millington
12. US 301 & Galena Rd., Galena
Maryland T Intersection
1. MD 235 & MD 6, Mechanicsville
2. US 50 & Carmichael Rd., Queenstown
3. MD 5 & Gallant Green Rd., Hughesville
4. MD 5 & Old Leonardtown Rd., Hughesville
5. Arundel Mills Circle & Mills Dr., Hanover
Modern Painted Roundabout
1. US 50 & Thompson Creek Rd., Stevensville
My source data is mainly from 2016 so there could be some new ones around the state.
Thank you!
-Elliott Plack
Consultant for MDOT
There's a grade-separated double roundabout interchange at Exit 13 on the Capital Beltway, Ritchie-Marlboro Road in PG County.
https://www.google.com/maps/@38.8676991,-76.8490137,15.92z
Welcome back
talllguy! Great to see you again.
This is a great list. Maryland has some very interesting interchange designs. I am particularly fascinated with their roundabout history. There is a lot across the whole state and they seem to have experimented with almost every kind of design philosophy.
Never heard the term "Maryland T" but this seems to be a T-intersection with a missing movement?
Never heard the term "Single Loop Interchange" either, but I like the terminology. British Columbia has a couple of these as well.
Quote from: 1995hoo on August 19, 2021, 12:43:24 PM
There's a grade-separated double roundabout interchange at Exit 13 on the Capital Beltway, Ritchie-Marlboro Road in PG County.
https://www.google.com/maps/@38.8676991,-76.8490137,15.92z
The history of that roundabout is quite intriguing. Sort-of British-like when first opened: no markings, no arrows, equal roadway width all the way around. Since modified of course. Reminds me of the early roundabouts in the mountains of Colorado back in the 90s.
(https://live.staticflickr.com/65535/51389368104_0302eacaa2_o.png)
Ritchie-Marlboro Interchange (https://flic.kr/p/2mi6WL1) by Jacob Root (https://www.flickr.com/photos/62537709@N03/), on Flickr
Adding in a couple SPUI's:
- I-70/US 40 & MD 85, Frederick
- I-270 & MD 189, Rockville
- MD 5 & MD 223, Clinton
Quote from: jakeroot on August 19, 2021, 12:59:24 PM
Never heard the term "Single Loop Interchange" either, but I like the terminology. British Columbia has a couple of these as well.
Parclo A1 :hmmm:
The interchange under construction I-270 & MD 85 Frederick will be unusual since it's considered a partial diverging diamond interchange:
https://www.youtube.com/watch?v=gnYs7a8YWpg&list=TLGGqH_FSzttdQMxOTA4MjAyMQ
If braided ramps are considered unusual then look at the new I-270 exit 12 at Watkins Mill Rd.
I would consider some interchanges like I-95 & I-695 (south), I-95 & I-195 and I-95 & MD 32 unusual for having some left side ramps.
Quote from: kphoger on August 19, 2021, 01:07:48 PM
Quote from: jakeroot on August 19, 2021, 12:59:24 PM
Never heard the term "Single Loop Interchange" either, but I like the terminology. British Columbia has a couple of these as well.
Parclo A1 :hmmm:
Possibly B1 as well. Either way, probably more correct than "single loop interchange".
Quote from: BrianP on August 19, 2021, 01:21:52 PM
The interchange under construction I-270 & MD 85 Frederick will be unusual since it's considered a partial diverging diamond interchange:
Neat. Not sure I've seen something like that before. Seems awfully complex. But I bet it will work well. I mean, it should with that many lanes.
Quote from: jakeroot on August 19, 2021, 02:07:48 PM
more correct
Does any agency other than Ontario officially use the whole A & B terminology?
Quote from: roadman65 on August 19, 2021, 02:18:53 PM
US 202 and DE 141 in Wilmington, DE. It is half SPUI and has two diamond ramps perpendicular to the Single Point Ramps.
Thread title: Unconventional Interchanges (and intersections)
in Maryland
It seems a lot of people beat me to the interchanges I know (Frederick and DC area), but here's my contributions:
-US 29 @ US 40, Ellicott City: Left merges from US 40 to US 29 SB. Causes a weave with the MD 100 exit to the south.
-I-68 @ I-70 and US 522, Hancock: Left exits from I-70 WB. I-70 EB has a left exit onto US 522 SB.
-US 50 from I-97 to US 301: Don't know if RIROs are considered unusual (definitely substandard), but may as well mention these. Don't think any other freeways in Maryland have multiple RIROs (Balt-Wash Parkway has one for the NSA, MD 32 for Fort Meade - usually these are restricted exits), aside from the grandfathered section of I-68.
-MD 32 @ MD 198, Odenton: Another double roundabout interchange.
-MD 4 @ Ritchie-Marlboro Road, Upper Marlboro: Don't even know what kind of interchange that's called, but it reminds me of this hacked together (https://www.google.com/maps/@42.4626676,-90.5158978,649m/data=!3m1!1e3) interchange on US 20 in Illinois.
-MD 4 @ MD 2: Another Maryland T.
US 113 is peppered with Maryland T's.
US 113 / Jarvis Road & Kepler Lane (https://www.google.com/maps/@38.4183269,-75.2121336,906m/data=!3m1!1e3)
US 113 / Shiloh Farms Road (https://www.google.com/maps/@38.2719156,-75.2407802,227m/data=!3m1!1e3)
US 113 / Croppers Island Road (https://www.google.com/maps/@38.2612774,-75.2557667,227m/data=!3m1!1e3)
There's no doubt several more of these along the widened portions of US 113 south of Newark, MD, but the satellite imagery Google has is out of date. Aside the entrance to Worcester Technical High School, I don't recall specifically where they were placed.
Another somewhat different-looking grade-separated double roundabout is on the Eastern Shore, US-301 and MD-304:
https://www.google.com/maps/@39.0271219,-76.0279324,17.62z
Quote from: kphoger on August 19, 2021, 02:28:24 PM
Quote from: jakeroot on August 19, 2021, 02:07:48 PM
more correct
Does any agency other than Ontario officially use the whole A & B terminology?
Not to my knowledge. It seems best to use whichever term you prefer :D
The A/B terminology is something I like because it's an algorithm of sorts.
US 40 at MD 24 is a single-loop interchange. US 40 at MD 43 is a single-loop interchange with an extra outer ramp. I think MD 24 at US 1 is a Green-T intersection.
The southern end of the Salisbury Beltway has an unusual double flyover interchange, where both sides of US 13 are above Business US 13 North and a single-track railroad.
The I-95/MD 43 interchange defies immediate description. I have no idea what the official label is for that interchange.
There are a lot more superstreet intersections on both MD 3 and US 301.
Does the US 50/US 113 cloverleaf count for this list because of the railroad level crossing on US 50 and two of the outer ramps?
Quote from: talllguy on August 19, 2021, 12:08:07 PM
....
Continuous Flow Intersection
1. MD 210 & MD 228, Accokeek
2. US 1 & MD 200(to be opened in 2014)
....
Just wanted to suggest that you update the status of #2 there as part of your project, as 2014 was seven years ago.
Two more come to mind for me.
Riva Rd. and MD 665 (Aris T. Allen Blvd.) is a SPUI.
MD 295 and Arundel Mills Blvd. is a "partial DDI" -- the crossroad does not continue west of the interchange.
You could also include the I-195 and MD 295 interchange, which is a parclo combined with a directional-T.
The MD 295/W. Nursery Road interchange is also noteworthy because of the three-lane right turn from the MD 295 north off ramp to eastbound W. Nursery Road.
The southern end of the MD 5/US 301 concurrency has a three-lane left turn for MD 5 south to cross US 301 north.
Anyone else know of a three-level stack interchange? Maryland has one!
MD-200 (ICC toll road) at U.S. 29 (https://www.google.com/maps/place/39%C2%B004'40.5%22N+76%C2%B057'08.9%22W/@39.0779281,-76.9612117,15z/data=!4m14!1m7!3m6!1s0x89b7c53c2de460c3:0x7a7216413ba1b0ba!2sSilver+Spring,+MD+20904!3b1!8m2!3d39.0533891!4d-76.9758274!3m5!1s0x0:0x0!7e2!8m2!3d39.0779238!4d-76.9524573) in Silver Spring, Montgomery County.
The cloverleaf ramp in the southwest quadrant of the interchange (U.S. 29 S to MD-200 E) is also cool.
Three level stack interchanges aren't really that rare. US 40/61 and I-270 in St Louis is one, as there's a pair of turbine ramps for the fourth movement.
Quote from: SkyPesos on August 19, 2021, 09:50:39 PM
Three level stack interchanges aren't really that rare. US 40/61 and I-270 in St Louis is one, as there's a pair of turbine ramps for the fourth movement.
I live close to one: NJ 17/4
Quote from: cpzilliacus on August 19, 2021, 09:27:37 PM
Anyone else know of a three-level stack interchange? Maryland has one!
MD-200 (ICC toll road) at U.S. 29 (https://www.google.com/maps/place/39%C2%B004'40.5%22N+76%C2%B057'08.9%22W/@39.0779281,-76.9612117,15z/data=!4m14!1m7!3m6!1s0x89b7c53c2de460c3:0x7a7216413ba1b0ba!2sSilver+Spring,+MD+20904!3b1!8m2!3d39.0533891!4d-76.9758274!3m5!1s0x0:0x0!7e2!8m2!3d39.0779238!4d-76.9524573) in Silver Spring, Montgomery County.
The cloverleaf ramp in the southwest quadrant of the interchange (U.S. 29 S to MD-200 E) is also cool.
Do you mean specifically 3-level stacks at interchanges with 4 legs? If not, the back-to-back I-68/I-70 & I-70/US 522 interchanges in Hancock are 3-level stacks (but with only 3 legs).
What distinguishes the J intersections along US-301 and US-15 from those constructed in the last decade along MD-404?
Quote from: BrianP on August 19, 2021, 01:21:52 PM
The interchange under construction I-270 & MD 85 Frederick will be unusual since it's considered a partial diverging diamond interchange:
https://www.youtube.com/watch?v=gnYs7a8YWpg&list=TLGGqH_FSzttdQMxOTA4MjAyMQ
Interesting and likely worthwhile, but that's not a DDI because the mainline roadways don't cross. It's actually a displaced left turn interchange. of course, there are an increasing number of displaced left turn intersections, which are usually misleadingly called "continuous flow intersections" despite the obvious fact that, with up to twice the usual number of traffic signals, they emphatically do not flow continuously. Why are engineers so bad at naming things? :pan:
I remembered a few more entries for this list (spot the theme):
- MD 166's intersection with S Rolling Road incorporates a Park and Ride inside the intersection, between each direction of travel.
- I-95's diamond interchange with MD 152 retained the original Mountain Road overpass, now signed Old Mountain Road, and the old road crosses two of the four ramps on the level. A Park and Ride is also included within the interchange next to I-95 north.
- MD 32's interchange with Broken Land Parkway has two Park and Ride lots stuffed into the spots where the NE and SE loop ramps would have been located.
- The interchange between US 1, MD 24 and MD 924 in Bel Air has a Park and Ride adjacent to the southbound side of MD 24/924, in the spot where the SW loop ramp would be.