Grade-separated interchanges (aka flyovers) might seem like the ultimate Safe System solution, but they’re not without their challenges. While they do separate traffic streams on the mainline, they create two new at-grade intersections which can have their own safety concerns (as seen in the video below).
This is why we attribute only a 60% Crash Reduction Factor to grade-separated interchanges. The safety of these two new intersections plays a critical role in the overall outcome.
The ultimate solution? Two roundabouts at these intersections, which significantly reduce conflict points and manage speeds effectively. If roundabouts aren’t feasible, we still need to think about how we address speed on the approaches to these at-grade intersections to ensure a safe outcome.
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