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

The Dummy Lights of New York

  A relic of the early days of motoring, dummy lights were traffic lights  that  were  placed  in the middle of a street intersection. In those early days, traffic shuffled through busy intersections with the help of a police officer who stood on top of a pedestal. As technology improved and electric traffic signals became commonplace, they were also  originally  positioned on a platform at the center of the intersection. Those traffic signals became known as  " dummy lights "  and were common until  traffic lights were moved  onto wires and poles that crossed above the intersection.  In New York State, only a handful of these dummy lights exist. The dummy lights  are found  in the Hudson Valley towns of Beacon and Croton-on-Hudson, plus there is an ongoing tug of war in Canajoharie in the Mohawk Valley, where their dummy light has been knocked down and replaced a few times. The dummy light in Canajoharie is currently out of commission, but popular demand has caused the dummy

Colorado Road (Fresno County)

Colorado Road is a rural highway located in San Joaquin Valley of western Fresno County.  Colorado Road services the city of San Joaquin in addition the unincorporated communities of Helm and Tranquility.  Colorado Road was constructed between 1910 and 1912 as a frontage road of the Hanford & Summit Lake Railway.  The roadway begins at California State Route 145 near Helm and terminates to the west at James Road in Tranquility.   Part 1; the history of Colorado Road Colorado Road was constructed as frontage road connecting the sidings of the Hanford & Summit Lake Railway.  The Hanford & Summit Lake Railway spanned from South Pacific Railroad West Side Line at Ingle junction southeast to the Coalinga Branch at Armona.  The Hanford & Summit Lake Railway broke ground during August 1910 and was complete by April 1912. The Hanford & Summit Lake Railway established numerous new sidings.  From Ingle the sidings of the line were Tranquility, Graham, San Joaquin, Caldwell, H

The Putah Creek Bridge of Monticello (former California State Route 28)

The Putah Creek Bridge was a masonry structure constructed during 1896 by Napa County to serve the community of Monticello.  The Putah Creek Bridge would be annexed into the State Highway System in 1933 when Legislative Route Number 6 was extended from Woodland Junction to Napa.  The Putah Creek Bridge was a component of the original California State Route 28 from 1934-1952.  The span briefly became part of California State Route 128 in 1953 until the highway was relocated as part of the Monticello Dam project in 1955.  Today the Putah Creek Bridge sits at the bottom of the Lake Berryessa reservoir and is accessible to divers.  Pictured as the blog cover is the Putah Creek Bridge as it was featured in the September 1950 California Highways & Public Works.   California State Route 28 can be seen crossing the Putah Creek Bridge near Monticello on the 1943 United States Geological Survey map of Copay.   The history of the Putah Creek Bridge The site of Monticello lies under the waters