#STEMengineering: DDI

For the He mau lanakila mākou, I decided to present the diverging diamond interchange, or DDI. first saw her own in the 1970s, but attitudinal barriers pushed America's to open in 2009 as the new I-44 and Kansas Expressway interchange in Springfield, MO.¹ The benefit of the unconventional design is the lack of left turns. By temporarily shifting traffic to the left side of the road, there is no oncoming traffic that one needs to cross when getting on or off the freeway. This lowers the number of opportunities cars have to conflict with each other from 32 to 14.² Further, it eliminates the need for a dedicated left-turn signal phase.³ It's cheaper, too, because it can use existing bridge decks and requires fewer lanes than other alternatives.⁴

---

¹ NPR

² Austin McConnnell

³ [MI DOT(PDF)|mdotcf.state.mi.us/public/tands/Details_Web/mdot_diverging_diamond_ interchange_info_guide.pdf]

⁴ Fed Hwy