State and national data clearly shows that the DDI design improves safety. For example, the number of severe accidents has significantly declined at the Chubbuck Interchange – also a DDI – since it was constructed. Reasons include:
- Left-turning traffic uses a dedicated “crossover” lane to safely turn, instead of waiting for oncoming traffic to stop.
- The design reduces the number of potential conflict points. (A traditional diamond interchange has 26 potential conflict points, while a DDI has 14.)
- The DDI design also reduces the opportunities for head-on collisions.