Three-level diamond interchange
From Wikipedia, the free encyclopedia
A three-level diamond interchange is a type of highway interchange where through traffic on both main roads is grade-separated from intersections which handle transferring traffic.[1] It is similar in design to a three-level stacked roundabout except for its use of (usually signalled) conventional intersections, and can be thought of as two diamond interchanges fused together.
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[edit] Description
In a three-level diamond interchange, the two main roads are on separate levels, and on a third level, usually (but not always) in the middle, there is a square of one-way roads. The square circulates counter-clockwise except in countries where traffic drives on the left. At each corner of the square is the terminal of an exit ramp from one main road and an entrance ramp to the other main road. Traffic transferring from one road to the other to make an overall right turn only passes through one corner of the square, at which point a right turn is made. Transfer traffic making an overall left turn must proceed straight through the first intersection it encounters, turn left at the next, and then proceed straight through a third intersection to enter the other main roadway.
[edit] Examples
Three-level diamond interchanges are most common in urban settings where the right-of-way for a new interchange must be kept to a minimum. Two three-level diamond interchanges exist along 8-Mile Rd (M-102) in Detroit; one at Woodward Ave (M-1) and one at the Chrysler Fwy (I-75). In Cedar Rapids, a slight variation of the three-level diamond interchange is formed where the collector/distributor roads for Interstate 380 and Collins Rd (Iowa Highway 100) intersect. On the East Coast, a three-level diamond interchange is utilized for Interstate 476 and U.S. Route 1 near Springfield in Delaware County. In Jefferson City, Missouri, a modified three-level diamond interchange exists where U.S. Routes 50, 54, and 63 come together, with the modification consisting of a flyover ramp for southbound U.S. 63 to go from its alignment with U.S. 54 northeast of the interchange to joining U.S. 50 southeast of the interchange on Whitten Expressway.
[edit] References
- ^ Indiana Department of Transportation, InterchangesPDF (203 KiB), pages 21 and 22
[edit] External links
- Kurumi's Field Guide to Interchanges: Volleyball Interchange
- Aerial view of a three-level diamond interchange (Interstate 380 and Iowa Highway 100 in Cedar Rapids, Iowa). Highway 100 runs from left to right; Interstate 380 runs from top to bottom.
| Types of road junctions | |
| Interchanges (grade separated) |
Cloverleaf - Diamond - Directional T - Diverging diamond Parclo - Trumpet - SPUI - Stack - Three-level diamond - Raindrop |
| Intersections (at-grade) |
Box junction - Continuous flow - Hook turn - Jughandle - Michigan left Quadrant roadway - Roundabout - Superstreet - 3-way junction - Traffic circle - Bowtie |
