Skip to main content

Remaining stretch of I-485 will feature three unique types of interchanges

The remaining 5.4 miles of I-485 currently under construction in Mecklenburg County will feature three unique interchanges.  All three are in use elsewhere within the country, but would be the first ones built in the Tar Heel State.

At two of the interchanges, the new designs are considered upgrades (in traffic flow and cost savings) versus what had originally been planned.

The interchange design names are Split Diamond, Diverging Diamond, and Turbine.

Heading East from the current terminus at NC 115, the three new interchange designs run as follows:

The Split Diamond interchange will be located at Prosperity Church Road.  This interchange will consist of two access roads and six roundabouts.

Split Diamond Interchange with Prosperity Church Road (NCDOT)
The Diverging Diamond Interchange (DDI), first used in Missouri, is starting to catch interest in North Carolina.  The interchange design, actually reverses the lanes of traffic on the surface/cross street.  This will be located at the Mallard Creek Road exit on I-485.

This design replaces a planned Single Point Urban Interchange (SPUI) for 485 and Mallard Creek.


We covered a Diverging Diamond Interchange back in October when NCDOT announced it is considering the design on NC 133 where it meets the US 74/76 freeway in Leland.  These two intersections, along with two more on nearby Interstate 85 at NC 73 and Poplar Tent Road, are some of seven prospective locations for this new style of interchange.

Finally, the Turbine - an interchange that has all left turn movements circling around a central bridge in a clockwise direction, creating a seamless movement between the two highways.  This replaces the previously planned four-level stack interchange.  (Similar in design to where I-77 and 485 meet in Southern Mecklenburg County.)

The new "Turbine" interchange at 85/485.  (NCDOT)      
According to NCDOT, this type of interchange will cost less to build and maintain, take up less space, and allow for less interruptions to existing I-85 traffic during construction.


Story Links:
Last Outerbelt juntions to display unique functions ---Charlotte Observer
I-485 Charlotte Outer Loop ---NCDOT

Comments

Froggie said…
NCDOT apparently doesn't see it as such, but I-40/Exit 195 (at NC 109) in Winston-Salem, is very much a split-diamond.
Anonymous said…
Should that be counterclockwise, or am I missing something? (Maybe clockwise in countries that drive on the left...)
Reminds me of my Alexandria Orb proposal:

http://wwwtripwithinthebeltway.blogspot.com/2007/02/alexandria-orb-page-one-news-december.html

http://wwwtripwithinthebeltway.blogspot.com/search/label/Alexandria%20Orb

Popular posts from this blog

California State Route 38

California State Route 38 is a fifty-nine-mile State Highway located entirety in San Bernardino County and a component of the Rim of the World Highway.  California State Route 38 begins at California State Route 18 at Bear Valley Dam of the San Bernardino Mountains and follows an easterly course on the north shore of Big Bear Lake.  California State Route 38 briefly multiplexes California State Route 18 near Baldwin Lake and branches east towards the 8,443-foot-high Onyx Summit.  From Onyx Summit the routing of California State Route 38 reverses course following a largely westward path through the San Bernardino Mountains towards a terminus at Interstate 10 in Redlands.   Pictured as the blog cover is California State Route 38 at Onyx Summit the day it opened to traffic on August 12th, 1961.   Part 1; the history of California State Route 38 California State Route 38 (CA 38) is generally considered to be the back way through the San Bernardino Mountains to Big Bear Lake of Bear Valley

The original alignment of California State Route 33 in Firebaugh

Firebaugh is a city located on the San Joaquin River of western Fresno County.  Firebaugh is one of the oldest American communities in San Joaquin Valley having been settled as the location of Firebaugh's Ferry in 1854.  Traditionally Firebaugh has been served by California State Route 33 which was one of the original Sign State Routes announced during August 1934.  In modern times California State Route 33 is aligned through Firebaugh on N Street.  Originally California State Route 33 headed southbound passed through Firebaugh via; N Street, 8th Street, O Street, 12th Street, Nees Avenue and Washoe Avenue.  The blog cover depicts early California State Route 33 near Firebaugh crossing over a one-lane canal bridge.  The image below is from the 1935 Division of Highways Map of Fresno County which depicts the original alignment of California State Route 33 in Firebaugh. Part 1; the history of California State Route 33 in Firebaugh The community of Firebaugh is named in honor of Andr

Driving the Watkins Glen Historic Road Course - New York

  Situated at the south end of Seneca Lake in the Finger Lakes region of Upstate New York, Watkins Glen is well known for wineries along Seneca Lake and waterfalls at Watkins Glen State Park . But one thing that gives the town much renown is its connection to the world of auto racing. The raceway at Watkins Glen Internationa l holds a number of big races every year, such as Six Hours at the Glen and the NASCAR Cup Series . The history of auto racing at Watkins Glen starts during the 1940s when the race followed a course on local roads and also through the streets of downtown Watkins Glen. It's a course that you can follow today, preferably at a more moderate speed than the auto racers of yore raced at. Let's explore the history of the original course, how it came to by and why it is no more. Organized races through the village of Watkins Glen and surrounding roads were first proposed and started by Cameron R. Argetsinger in 1948, marking the beginning of post-war sports car