Its design can appear baffling at first, but the DDI presents drivers with far fewer opportunities to collide with each other than traditional four-way intersections.
Laura Bliss covers the spread of the diverging diamond interchange, or DDI. "Rather [than] make drivers turn at a right angle to merge onto a highway, the two directions of traffic diverge and ribbon over one another. One lane peels off to funnel cars onto the highway, and they never have to turn against traffic."
Bliss includes an embedded Youtube video from the city of Calgary, which cheerily explains how drivers should use a DDI.
"DDIs are proliferating because they're safer than a traditional four-way intersection. Where two, two-lane roadways intersect, drivers have 32 separate opportunities to collide into each other. In a DDI, there are only 14." They can also incorporate pedestrian crossings, as the Calgary video shows.
FULL STORY: The Diverging Diamond Interchange Is Coming to a Road Near You
‘Forward Together’ Bus System Redesign Rolling Out in Portland
Portland is redesigning its bus system to respond to the changing patterns of the post-pandemic world—with twin goals of increasing ridership and improving equity.
Plan to Potentially Remove Downtown Milwaukee’s Interstate Faces Public Scrutiny
The public is weighing in on a suite of options for repairing, replacing, or removing Interstate 794 in downtown Milwaukee.
Can New York City Go Green Without Renewable Rikers?
New York City’s bold proposal to close the jail on Rikers Island and replace it with green infrastructure is in jeopardy. Will this compromise the city’s ambitious climate goals?
700-Acre Master-Planned Community Planned in Utah
A massive development plan is taking shape for lakefront property in Vineyard, Utah—on the site of a former U.S. Steel Geneva Works facility.
More Cities Ponder the End of Drive-Thrus
Drive-thru fast food restaurants might be a staple of American life, but several U.S. cities are actively considering prohibiting the development of new drive-thrus for the benefit of traffic safety, air quality, and congestion.
Air Pollution World’s Worst Public Health Threat, Report Says
Air pollution is more likely to take years life off the lifespan of the average human than any other external factor, according to a recent report out of the University of Chicago.
Placer County
City of Morganton
HUD's Office of Policy Development and Research
Dongguan Binhaiwan Bay Area Management Committee
City of Waukesha, WI
Los Angeles County Metropolitan Transportation Authority
Indiana Borough
Urban Design for Planners 1: Software Tools
This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.
Planning for Universal Design
Learn the tools for implementing Universal Design in planning regulations.